Master’s dissertation submitted in partial fulfilment of the requirements for the joint degree of
International Master of Science
in Environmental Technology and Engineering
an Erasmus Mundus Master Course
jointly organized by UGent (Belgium), ICTP (Prague) and UNESCO‐IHE (the Netherlands)
Academic year 2012 – 2014
Development of an Environment Impact Model for Open Dumping
of Electronic Waste
Host University:
UNESCO-IHE Institute for Water Education
First name Name Promotor: Prof. dr. Kenneth Irvine
This thesis was elaborated at UNESCO-IHE Institute for Water Education and defended at UNESCO-IHE Institute for Water Education, Delft, the Netherlands within the framework of the European Erasmus
Mundus Programme “Erasmus Mundus International Master of Science in Environmental Technology and Engineering " (Course N° 2011-0172)
Development of an environmental impact model for open dumping of
electronic waste
By
Alkida Prodani
IMETE
Supervisor
Prof. Dr. Kenneth Irvine
Mentors
Assoc. Prof. Dr. Maarten Siebel
Prof. Dr. Susanne Rotter
Delft August 2014
iii
Acknowledgements
Writing of this thesis marks the finishing of the IMETE programme, therefore I would like to say two
words of gratitude to many people who helped me reach the goal of this academic journey.
First of all I would like to express my deep gratitude and appreciation to Prof. Vera Susanne Rotter, Dr.
Maarten Seibel and Prof. Kenneth Irvine for guiding me through such a challenging academic endeavor.
Without their constant involvement in every step, from the beginning to the end, the writing of the
thesis would have not been so enjoyable and smooth.
I would also like to express my appreciation to IMETE Secretariat for providing all the necessary means to
make our stay and the study time in the three different beautiful places comfortable.
A special thank you goes to UNESCO-IHE laboratory staff for their unreserved technical assistance and
readiness to help any time needed. Moreover, without their timely delivery of experimental results, the
completion of this thesis on time would have not been possible.
Last, but not least, a special thanks goes to my family and especially to my son Kristof for their support
and encouragement and to my friends in Delft, Ghent and Prague for making these two years so
pleasant.
A big thank you also to anyone I failed to mention here.
iv
Abstract
The use of electronic and electric devices – computers, mobile phones, TV sets and many more – has
increased drastically due to the increased demand from consumers and limited life cycle of the product.
This has directly affected the amount of electronic and electric wastes (WEEE) produced and represent
an important challenge for their management due to the high toxicity of their content. The majority of
toxic compounds (Pb, Hg, Cd) are found in Printed Circuit Boards (PCB) and display units and their
disposal poses health and environmental risks. Recycling and landfilling are two common management
approaches, but the high costs involved make landfilling the most used method, especially in developing
countries. This is however not a safe method to treat WEEE since their toxic may be leached into the
environment. Therefore, this study aims to (i) quantify the leachable metal content from WEEE related
treatment residues under selected conditions, (ii) assess the leaching test results relative to a potential
leachable metal content under defined environmental conditions related to open dumping practices, (iii)
implement the experimental data in models for prediction of leachable metal content of the investigated
materials, and at the end, to make some recommendations for the (relatively) safe disposal of WEEE.
To reach the objectives, pH controlled leaching tests characterizing the leachable metal content as
function of pH (CEN/TS 14429, 2005) and liquid-solid ratios dependency test (CEN/TS 12457 1-4, 2002)
have been conducted. Three separated input matrices such as PCBs with particle size less than 10 mm,
shredder fluff and Li-ion battery ash have been investigated.
The leachable metal content from PCBs, Shredder fluff and Li-ion battery ash under extreme conditions
such as pH 3 and liquid–solid ratio 10 (l/kg) show that Cu, Pb, Zn, Fe, Cd, Ni, Co and As are the most
abundant metals in three materials. Pb and Cu have the highest concentrations in PCBs, Cd and Ba in
shredder fluff, and Fe, Ni, Co and As in Li-ion battery ash. The leachable metal content is found to be
strongly pH dependent. At pH 3, it is around 10 times lower compared to total metal content, whereas at
L/S 10 (l/kg) is around 5000 - 10,000 times lower. For particular metals, leaching test results show that Pb
is the most leached metal in acidic condition and L/S 10 (l/kg). Its leachability decreased with increasing
pH due to presence of Fe and Zn as fast oxidizers. Also, Cu found in PCBs showed the highest leachability
at acidic pH, whereas Cd appeared to be the most leachable metal in L/S 10 (l/kg).
When considering the total leachable content, it can be shown that these levels of total metal
concentrations do not comply with class IV landfill acceptance criteria, suggesting that the underground
hazardous waste disposal is not an option for the investigated material. However, the leachable metal
content under neutral pH at L/S 10 does comply with the hazardous waste landfill acceptance criteria. In
terms of soil thresholds, the tested materials impose risk for soil contamination, given the fact that total
metal content exceeds even the highest limits of soil threshold values. Therefore, the disposal of the
investigated materials in open dumpsites may lead to surface water contamination and migration to
wider areas.
i
Contents Acknowledgements ...................................................................................................................................... iii
Abstract ........................................................................................................................................................ iv
CHAPTER I ..................................................................................................................................................... 1
1.1 Problem Statement ................................................................................................................... 1
1.2 Project Aim and Objectives ....................................................................................................... 2
1.3 Research scope ......................................................................................................................... 2
1.4 Structure of the thesis .............................................................................................................. 2
CHAPTER II .................................................................................................................................................... 3
2.1 Definitions, compositions and recovery, treatment and disposal methods of WEEE and
WEEE related components ................................................................................................................... 3
2.2 Factors affecting heavy metal mobility ..................................................................................... 6
2.3 Leaching test methods for granular material ........................................................................... 9
2.4 Simulation models and parameters to assess the leachable metal content .......................... 10
2.5 Data on the leachable metal content from WEEE related fractions ....................................... 12
2.6 Toxicity assessment of metal emissions ................................................................................. 15
2.7 Environmental threshold values for metal emissions ............................................................ 15
CHAPTER III ................................................................................................................................................. 18
3. MATERIALS AND METHODS ............................................................................................................ 18
3.1 Overview of experimental design ........................................................................................... 18
3.2 Origin and description of the input materials ......................................................................... 19
3.3 Leaching test procedures ........................................................................................................ 20
CHAPTER IV ................................................................................................................................................. 27
4.1 Quantification on the leachable metal content from WEEE related residues under selected
test conditions .................................................................................................................................... 27
4.2 Metal behavior under given environmental conditions. Prediction of metal release based on
4.3 Compliance of metal emissions from three materials with emission and criteria ................. 34
4.4 Most relevant toxic metals released from disposal of WEEE ................................................. 37
CHAPTER V .................................................................................................................................................. 39
5.1 Quantification of the specific release of metals from WEEE related treatment residues under
selected test condition ........................................................................................................................ 39
5.2 Prediction of metal release based on geochemical modeling ................................................ 43
5.3 Comparison of environmental quality and landfill acceptance criteria .................................. 44
5.4 Toxicity assessment of WEEE related metal emission ............................................................ 45
CHAPTER V .................................................................................................................................................. 48
5. CONCLUSIONS and RECOMMENDATIONS ...................................................................................... 48
Figure 5 Prediction of Leaching Test Data for contaminated soil by geochemical speciation ................... 11
Figure 6 Overview of Leach XS database .................................................................................................... 12
Figure 7 Extract metal concentration from pH dependency test under oxic conditions ........................... 13
Figure 8 Schematic of landfill simulation column by mixing different types of electronic devices with
municipal waste .......................................................................................................................................... 14
Figure 9 Average lead concentration versus the percentage of ferrous metal content for PCBs from 13
electronic devices in PCLP tests (Musson et al. 2006b) .............................................................................. 14
Figure 10 Overview of experimental set up including the research questions to be answered based on
the leaching results ..................................................................................................................................... 18
Figure 11 Grading curve for PCB < 10 mm, shredder fluff and Li-ion Battery ash testing matrices ........... 20
Figure 12 pH dependency test for input waste matrices at L/S 10 l/kg and contact time 48 hours .......... 21
Figure 13 Filtered samples after second filtration with 0.45 µm pore size cellulose acetate filters .......... 22
iv
Figure 14 Total metal content of nine metals from PCB < 10 mm, shredder fluff and Li-ion battery ash
input material (n=3) (aqua regia digestion of the original test material ground to < 0.5mm) ................... 27
Figure 15 The leachable metal content from L/S dependency test at L/S 10 L/kg and pH dependency test
at pH 3, from PCB < 10 mm, shredder fluff and Li-ion battery ash ............................................................. 28
Figure 16 The leachable metal content from three different material such as Li-ion Battery ash, PCB < 10
mm and Shredder fluff as function of pH, at L/S 10 (l/kg), after 48 hours contact time ............................ 29
Figure 17 Relative share of nine lead metals in PCB, shredder fluff and Li-ion battery ash for the total
metal content (aqua regia digestion) and metal release from L/S dependency test (L/S 10 l/kg) and pH
dependency test (pH 3) ............................................................................................................................... 30
Figure 18 Relative share of nine lead metals and the leachable content for three materials and tests
together in PCB, shredder fluff and Li-ion battery ash for the total metal content (aqua regia digestion)
Figure 19 The relation of pH as function of L/S ratio from Li-ion battery, Shredder fluff and PCB < 10 mm
at L/S 10, 5, 2, 1 and 0.5 (l/kg) and for 72 hours contact time ................................................................... 31
Figure 20 pH depencency prediction modelling results for inorganic constituents in comparison with pH
dependency leaching test results for three input materials Li-ion Battery ash, shredder fluff and PCB < 10
mm. ............................................................................................................................................................. 34
Figure 21 The normalized results for the leachable content at L/S 10 (l/kg) compared to the EU
acceptance criteria for disposal of WEEE in hazardous waste, Class III, Li-ion battery ash, shredder fluff
and PCB < 10 mm from L/S dependency test (EN 12457-4) ....................................................................... 35
Figure 22 The normalized results for the leachable total content with aqua regia extraction compared to
the EU acceptance criteria for disposal of WEEE into underground landfill of hazardous waste, Class IV,
for Li-ion battery ash, shredder fluff and PCB < 10 mm ............................................................................. 35
Figure 23 The normalized results for the leachable metal content and total metal content compared to
lower and upper threshold limits for soil for Li-ion battery ash, shredder fluff and PCB < 10 mm ........... 36
Figure 24 Relative toxicity contribution of Ba, Cd, Co, Cu Ni and Pb, lead metals for two release
scenarios, pH dependency test (pH 3) and L/S dependency test (L/S 10 L/kg) for human toxicity and
Figure 25 Relative share of Fe, Cu, Zn and Pb in PCB, shredder fluff and Li-ion battery ash for the total
metal content (aqua regia digestion) and metal release from L/S dependency test (L/S 10 l/kg) and pH
dependency test (pH 3) ............................................................................................................................... 41
Figure 26 pH depencency prediction and phase distribution modelling results for Cu and Pb in
comparison with pH dependency leaching test results from Li-ion Battery ash ........................................ 44
Figure 27 Primary sampling procedure for shredder PCBs, Shredder fluff and Li – ion battery ash .......... 59
Figure 28 The leachable metal content from L/S dependency test at L/S 10 L/kg and pH dependency test
at pH 3, from PCB < 10 mm, shredder fluff and Li-ion battery ash ............................................................. 67
Figure 29 Phase distribution modelling results for toxic metals from PCB < 10 mm, Shredder fluff and Li-
ion Battery ash ............................................................................................................................................ 74
RoHS Restriction of the Use of certain Hazardous Substances
SAB Science Advisory Board (of the EPA)
Sb Antimony
Se Selenium
Sn Tin
Ta Tantalum
TC Toxicity Characteristic
TCLP Toxicity Characteristic Leaching Procedure
Te Tellurium
TOC Total Organic Carbon
TV Television
UNEP United Nation Environment Program
US United States
WEEE Waste Electrical and Electronic Equipment
Zn Zinc
1
CHAPTER I
1. INTRODUCTION
1.1 Problem Statement
The use of electronic and electric devices, such as computers, mobile phones, TV sets and many more devices
has increased drastically. This is attributed mainly to the increase in demand from the consumers, as well as to
limited life cycle of the product. For instance, computer use alone, from 1994 until 2004, has increased by
around 80% (Widmer et al. 2005). The increased demand for electric and electronic devices has directly
affected the amount of waste produced. The electronic and electric wastes, known commonly as WEEE, have
increased dramatically and their management represents an important challenge (UNEP, 2009).
The challenge consists in the management approach and in the content of the e-waste themselves. In terms of
management, two common approaches are commonly used, recycling and landfilling. Many formal programs
have been established to recycle obsolete e-wastes, but many of them have yielded mixed results. Huisman et
al. (2007), reported that only 27% of obsolete collected equipments are recycled in Europe. What makes the e-
waste management further complex is the elemental composition, which includes toxic compounds and
valuable elements. The precious elements (Au, Ag, Pt, Pd) are mainly found in printed circuit boards (Chancerel
et al. 2009). Meanwhile, the majority of toxic compounds (Pb, Hg, Cd) are found in Printed Circuit Boards (PCB)
and display units and their disposal represent health and environmental risks, especially in developing
countries (Townsend, 2014; Tsydenova et al. 2011). Recycling and recovery in these countries is carried out by
primitive and informal sector-level unsafe methods. This is derived by the lack of legislation or poor regulation
related to a safe and controlled process (ibid). Open dumpsites and landfilling of WEEE remain the most used
methods in developing countries because of the low cost involved, although the risk they impose on human
health is immense due to high toxic content of certain elements, mainly heavy metals (Tsydenova et al. 2011).
Open dumpsites are composed of unsorted waste and are exposed continuously to atmospheric conditions
such as rainfall and differences in temperature, as well as, lack of gas collection systems. Therefore, biological,
chemical and physical processed may be affected. In landfills, the majority of heavy metals are retained by Mn
and Fe oxides, adsorbed by organic matter and precipitate as sulfides in anaerobic conditions. Meanwhile, in
open dumpsites, this mechanism can be interfered by oxygen penetration, which enhances metal mobility by
diffusion, posing risk to the environment and public health (Prechthai et al. 2008; Sang et al. 2012).
Most of toxic elements found in electronic equipments such as PCBs, batteries etc., exceed the toxicity
characteristic threshold limits and in some cases even the acceptance criteria for hazardous waste landfills.
In order to understand and analyze the leachable metal content, different tests need to be performed for
assessing the leaching behavior of inorganic constituents. In this study, we conduct a pH controlled leaching
tests characterizing the leachable metal content as function of pH (CEN/TS 14429, 2005) and liquid to solid
ratio dependency test. We investigate changes in concentration at different liquid to solid ratios (CEN/TS
12457 1-5, 2002), with three separated input materials such as PCBs with particle size less than 10 mm,
shredder fluff and Li-ion battery ash.
2
1.2 Project Aim and Objectives
The aim of this research is to assess the environmental impacts of leaching of heavy metal fractions from WEEE
in landfill conditions. The objectives of the work are:
(i) to quantify the leachable metal content from WEEE related treatment residues under selected
conditions.
(ii) to assess the leaching test results relative to a potential leachable metal content under defined
environmental conditions related to open dumping practices.
(iii) to implement the experimental data in models for prediction of leachable metal content of the
investigated materials.
(iv) to make recommendations for the (relatively) safe disposal of WEEE.
1.3 Research scope
This study is focused on the characterization of three input materials based on the leaching experiments,
simulating landfill conditions and investigating parameters such as pH and liquid to solid ratio over a defined
time period.
This research investigates the quantification of leachable metal content from different granular materials by
the same leaching methods. The mobility of a number of inorganic elements have been investigated such as
Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb and Cl. Calculations have been done for hydroxides. The leachable metal content
is carried out only in granular material. Monolithic materials are not subject of this study.
1.4 Structure of the thesis
This thesis is organized in the following way. Chapter 2 provides an overview of the state of the art on the
factors affecting heavy metal mobility, concentration of heavy metals in WEEE leachate, leaching behavior of
trace elements and their concentrations. Chapter 3, outlines the methodological approach and the procedures
undertaken to carry out the study. Chapter 4, highlights the main results of the experiments Chapter 5, will
discuss the experimental results against the background of the existing knowledge as set forth in Chapter 2.
The last section – Chapter 6 – will present the conclusion of the work.
3
CHAPTER II
2. BACKGROUND
2.1 Definitions, compositions and recovery, treatment and disposal methods of WEEE and
WEEE related components
2.1.a Heavy metals in WEEE components
Widmer et al. (2005) adapted a list of definitions for Waste Electrical and Electronic Equipment (WEEE). Based
on this list, “E-waste encompasses a broad and growing range of electronic devices ranging from large
household devices such as refrigerators, air conditioners, cell phones, personal stereos, and consumer
electronics to computers which have been discarded by their users.” (Puckett et al. 2002).
Based on the Directive 2012/19/EU on WEEE, the basic categories belonging to WEEE include large and small
household appliances, IT and telecommunication equipment (ICT) and consumer equipment (CE) that present
95% of WEEE, whereas 5% of WEEE generated includes lighting equipment, electrical and electronic tools, toys,
medical equipment, monitoring and control instruments and automatic dispensers.
Management of WEEE is complex due to the diversity of the element composition including toxic metals (Pb,
Hg, Cd) located in Printed Circuit Boards (PCB), switches and batteries respectively, precious elements (Au, Ag,
Pt, Pd) found mainly in printed wiring boards, special elements (In, Se, Te, Ta, Bi, Sb), or organic
[Polychlorinated Biphenyl (PCB) and Biphenyl Flame Retardant (BFR)] and inorganic compounds. Toxic
compounds are found in PCBs and display units (Townsend 2014; Chancerel et al. 2009).
Metals with the highest concentration are Cu, Pb and Sn, whereas Cd, Hg, etc and precious elements, such as
Au occur in lower concentrations. Considering organic polychlorinated biphenyls are mainly found in older
equipments such as capacitors, cables etc, but the most toxic organic compound is evaluated to be BFR mainly
used in plastics to avoid flame risks. TV equipments for instance may contain a large percentage of BFR that
can reach up to ten percent (Townsend 2014; Chancerel et al. 2009).
Most of toxic compounds found in electronic equipments such as PCBs, batteries etc., exceed the toxicity
characteristic threshold limits and in some cases even the acceptance criteria for hazardous waste landfills,
posing environmental and human health risk. As above, an overview of substances of concern metal
concentration in WEEE components for metals of concern is summarized from different sources and presented
in Table 1.
4
Table 1 Metal concentration in WEEE components from different sources
Reference Component WEEE
Metal used Metal concentration in WEEE components (mg/kg)
TCLP(c) threshold limit (mg/kg)
EU acceptance criteria(d) (mg/kg)
Tsydenova & Bengtsson 2011 Yoo et al. 2009
PCB(a) Pb – solder Cd – contacts
10,100 191,100
50 10
10 – 50 1 – 5
Dimitrakakis et al. 2009
WEEE – small household electronics
Pb – solder Cd – plastic case Cu – plastic case
33.64 37.73 565
50 10 250
10 – 50 1 – 5 50 – 100
Matsuto et al. 2004
PCB – TV and radio
Pb – PCB, CRT(b)
Cd Cu
7,230 – 9,530 5.31 97,200
50 10 250
10 – 50 1 – 5 50 – 100
Kang et al. 2013 Li – ion Batteries
Cu – conductor Co – cathode material Ni
54,100 – 152,000(c) 58,000 – 278,000(c)
120 – 30,500(c)
250 - 200
50 – 100 - 10 – 40
(a) Printed circuit board; (b) Cathode ray tube; (c) Results from total threshold limit concentration – Toxicity Characteristic Leaching Procedure (TTLCP); (d) Range of criteria for waste acceptable at landfills for non – hazardous to hazardous waste (Class II, III and IV)
Within the category of WEEE and composition, different studies have focused on “low grade PCBs”, shredder
fluff and combusted Li-ion battery ash.
“Low grade PCBs” belongs to the category of large and small household appliances as specified in Directive
2012/19/EU, originating from household WEEE plant. These kind of PCBs are mainly composed of a mixture of
epoxy and acrylic resin solder and BFR, where 1/3 of the surface is covered by 70 µm Cu layer and partially,
8µm Pb layer (Yang 1993). The acid resins contain the carboxylic group in their chemical structure which may
form complexes with heavy metals in alkaline region (Bernier 1988). Yang (1993) showed that high level of Pb,
Zn, Cu and Cd are found in PCBs in color televisions, whereas Fe and Ni are mostly found in integrated circuits
or chips.
Boughton & Horvath (2006) showed that glass, plastics, fabrics, ferrous and non – ferrous metals are found in
shredder fluff, which mainly originate from heavy metal recovery industries for automobiles and appliances.
Based on the above study, this composition consists of 50 percent non – combustible material such as metals,
glass and ash. Metals in shredder fluff as, adopted from different studies, remains mainly for Ba, Pb, Cd, Cr, Cu,
Ni, Zn, Hg and As (Boughton & Horvath 2006).
Li-Ion batteries are composed by Lithium-thionyl-chloride (Li-SOCl2) primary non rechargeable cells and Lithium
– iron phosphate (LiFePO4) secondary rechargeable cells, where LiFePO4 is used as a cathode material. Both
primary and secondary cells differ from each other from their cathode material (Jain 1999). The main metallic
content of Li-ion batteries stands for Cu and Al used in conductors and Co and Li present in cathode material
consisting of around 97.3 percent of the batteries, whereas the presence of other metals such as Mn, Fe, Zn, Ni
5
and Co depends on the composition of cathode material, such as presence of LiNiO2, Li-MnO2, LiFePO4,
Li(NiCo)-O2 (Kang et al. 2013).
2.1.c Treatment and disposal methods for WEEE and WEEE components
In general precious metals such as Ag, Au, Pt and Pd and Cu found in PCBs and cables are recovered by
smelting processes. In principle, two processes are involved in the recovery dismantling and mechanical
processing and metallurgical process (Tsydenova & Bengtsson 2011). One other method is the centrifugal
separation and vacuum pyrolysis (Zhou & Qiu 2009). These processes are, however, no risk free and its risk
level is not documented even not in developed countries (Tsydenova & Bengtsson 2011). The presence of toxic
chemicals poses risks to human health and environment during the processes of recycling and recovery of
heavy metals. The level of risk to workers and the environment depends on the individual facilities and their
operation system such as dismantling manually or mechanically like shredders (ibid) (Figure 1).
Figure 1 Metal recovery facility in developed countries
Cd Gastrointestinal disorders, renal dysfunctions and lung cancer in long exposure
4.368
Sarode & Jadhav 2010 Pizzol et al. 2011
Ni Respiratory and cardiovascular diseases 0.007
Piotrowski & Coleman 1980 Pizzol et al. 2011
Pb Inhibition to hemoglobin synthesis, anemia, renal, cardiovascular reproduction effects, gastric disorders, cerebral injury, lead poisoning
0.919
Abernathy et al. 2000 Pizzol et al. 2011
As Skin cancer, diabetes, neuropathy, cardiovascular diseases
3.023
Pizzol et al. 2011 Ba Stomach diseases and abdominal cramps, vomiting, diarrhea, skin irritation, bones and teeth damage, heart diseases and paralysis,
0.018
(a) U.S. Agency for toxic substances and disease registry, 2004; (b) Toxicological human health effect - minimal to maximal daily human exposure to hazardous substances; (c) Characterization factor for human toxicity effect expressed in disease cases per kg emitted – Source: www.usetox.org; (d) changes in life time disease because of changes in life time intake (cases / kg)
Matharu (2013) investigated the potential metal recovery from landfill leachate and usually the composition of
landfill determines the type and quantity of metals in the leachate. However, their concentrations are not
significant and further techniques and technologies need to be applied in terms of recovery of valuable metals
(Matharu 2013).
2.2 Factors affecting heavy metal mobility
The leachable metal content from solid to liquid phase is related to the specifies of input material as well as to
the chemical and physical processes and their synergy (Sloot, 2004). The degradation of organic material
comprises both aerobic and anaerobic stages where oxygen plays an important role. Initially aerobic process or
acid formation stage with pH drop takes place. Further, oxygen starts depleting, leading to exponential drop of
redox potential, giving room to sulphates, nitrates and Mn, Al and Fe oxides to act as oxidizing agents.
Methane formation takes place further, in anaerobic conditions, where pH starts increasing to neutral levels
from 6 to 8. The processes are derived by microbial activities, such as sulphate reducing bacteria, methanogens
etc (Bozkurt et al,. 2000).
The contact of inorganic compounds with rain water may lead to the dissolution of metals and infiltration or
transportation to the lower layers where precipitation with carbonates, hydroxides and sulfides, will take
place. However it is difficult to predict all processes that lead to metal mobility, but the main important
mechanisms includes solubility and transport through a number of processes such as complexation,
dissolution, precipitation through binding capacities to sulfides and humic substances, sorption capacities of
Mn and Fe oxides, adsorption, ion exchange etc. (Borzkurt et al,. 2000).
Open dumpsites as opposed to landfills, are composed of unsorted waste and are exposed continuously to
atmospheric conditions such as rainfall and differences in temperature, as well as, exposed to lack of gas
collection systems (Sang et al. 2012; Hughes et al. 1959). This means that all the above processes are affected.
On the other hand, the majority of heavy metals in landfills is retained by Mn and Fe oxides, adsorbed by
organic matter and further down precipitate as sulfides, carbonates and hydroxides minimizing heavy metal
mobility. In open dumpsites, this mechanism can be interfered by oxygen penetration into the layers, which
enhance metal mobility by diffusion from areas with high concentrations to areas with low concentrations,
posing risk to the environment and public health (Prechthai et al. 2008; Sang et al. 2012).
Sloot & Dijkstra (2004), showed that the solubility, sorption and availability in the input material, play an
important role in heavy metal mobility, whereas advection, percolation and diffusion play a role in transport
mechanisms of metal release from the solid to liquid phase.
2.2.a Chemical form of elements and chemical processes
Metals are found in solution in the form of free ions, inorganic and organic complexes and bound to
suspended particles such as organic matter, whereas in solid phase metals may be bounded to reactive
surfaces or organic matter, bounded with Fe and Mg oxides and precipitated as carbonates, sulfides,
phosphates, or silicates (Tack FMG, 2010).
Role of Organic Matter
Organic matter is composed by fulvic acid (FA), which is the dissolved part of humic substances in aqueous
environments at all pH ranges, humic acid (HA) the insoluble solid form of humic substances which becomes
soluble at alkaline region and humin the solid part humic substances at all pH ranges (Aiken et al. 1985).
Humic substances may form complexes with metals and the dissolved fraction of humic substances may
enhance the metal leachability (Sloot et al. 2004). Christensen & Christensen (2000), showed that Cd, Ni and Zn
considered as the most mobile heavy metals in soil and groundwater, have a high affinity with dissolved
organic carbon forming the complexes in the order Zn < Cd < Ni. However, metal complexation is also strongly
dependent on the pH of the system (Christensen & Christensen 2000)
Role of pH and Redox Potential
Sloot and Dijkstra (2010) showed that metal solubility and sorption processes are pH dependent. Based on the
experimental acidic pH, Al-Abed et al. (2006) found that, metal leaching is maximized for cationic trace
8
elements. On the other hand, increasing pH leads to ion precipitation and possible co-precipitation of the
above metals. However, the influence of pH on the leachability of the metals associated with DOC
complexation and salts such as Na, K, Ca and Cl-, plays an important role in the mobility of heavy metals (Quina
et al. 2009). Oxidation and reduction processes influence the mobility of heavy metals, where oxidation
enhances the solubility and reduction processes lead to a reduced environment, where the solubility rate is
decreased (Sloot, 2010).
Role of chlorides, carbonates and sulfide precipitation
Tack (2010) showed that metallic cations are bounded to inorganic anions such as Cl- especially with Cd2+,
whereas carbonate inorganic ligands such as OH- form precipitated hydroxides. Hydroxide complex formation
is found to happen for different cations at pH higher than 12, whereas chloride precipitations may happen at
pH lower than 9 (Quina et al. 2009). Some minerals may precipitate in the form of colloids with size less than
10µm in diameter. They may bind the trace elements and because of their mobility they may transport the
trace elements into the leaching outflow. These minerals may be aluminum hydroxide - Al(OH)3, silica – SiO2,
and ferrihydrite – Fe(OH)3. However the transport of trace elements in this case depends on the stability of
colloids in the landfill body (McCarthy & Zachara 1989). All these forms of complexation may play an important
role to the mobility and availability of heavy metals.
2.2.b Physical processes
Processes like advection, percolation and diffusion are the physical factors that play a role in transport of metal
release from the solid to the liquid phase (Sloot, 2004). Physical factors are related to particle size, their shape
and porosity, flow rate, etc. (Quina et al. 2009).
Role of particle size and porosity
Particle size plays a role at the time when the contaminant passes from the particles to the liquid phase. The
smaller the particle size the faster is this transportation (Sloot, 2004). However, Prange & Garvey (1990)
investigated whether the particle size reduction plays a role in the release of As and Cr from cement solidified
waste in TCLP experiments. The results showed that As and Cr concentrations were significantly reduced by
reduction in particle size within the fractions between 0.5 to 9.5, mm giving the fact that (CaOH)2
neutralization capacity of small cement particle size was faster compared to the bigger particles.
Sloot (2004) showed that porosity may affect the release of heavy metals from solid to liquid phase. The
release is higher where the porosity is higher. Heavy metal mobility in soil depends on the type of soil which
means that in low permeability soils the metals are bound to the soil particles (Antoniadis & McKinley 2003).
2.2.c Other factors
Contact time, pH in the environment, temperature, moisture content, redox potential of the environment,
microbial activity etc are other factors that affect the mobility of heavy metals in the environment (Sloot,
2004). Mobility of Cu, Hg, Cr, Cd and Zn in the soil solution for instance is shown to be time dependent (Selim
et al. 1990).
9
To conclude, all above factors are needed to develop an environmental model on the leachable metal content
of inorganic compounds. Chemical speciation and pH dependent leaching prediction requires data on pH
dependency tests as well as data on precipitation/dissolution reactions. Also, transport prediction scenarios,
needs percolation tests, as well as a variety of field conditions such as starting and boundary conditions
estimating the short and long term release (Sloot, 2004).
2.3 Leaching test methods for granular material
There is a variety of leaching test methods used for assessing the leaching behavior of organic and inorganic
constituents. Standards have been developed by U.S. European Protection Agency (EPA) and European
Committee for Standardization (CEN). However, efforts have been done to harmonize the methods giving the
fact that they show similarities in leaching methods by both EPA and CEN (Sloot et al. 2012).
Leaching behavior for granular materials can be characterized using:
1. pH dependency tests, characterizing the leaching behavior of constituents as function of pH at liquid to
solid ration 10 l/kg using particle sized reduced material (CEN/TS 14429, 2005; US EPA Method 1313,
2009)
2. Liquid to solid partitioning as function of liquid to solid (L/S) ratios under conditions to reach the
equilibrium between liquid and solid phase. Five semi continuous batch tests are running in parallel
with the range of L/S ratios 0.5, 1, 2, 5 and 10 l/kg in order to investigate changes in concentration at
different L/S ratios (CEN/TS 12457 1-5, 2002; US EPA Method 1316, 2012).
3. Percolation test using up-flow percolation column. It is a continuous flow process where the granular
material is packed in columns and is contacting the leachate continuously at low flow rate (CEN/TS
14405, 2004; US EPA Method 1314, 2009).
Another method developed by EPA is the Extraction Procedure (EP) Method 1310B, based on the Resource
Conservation and Recovery Act (RCRA), enacted in 1976, amended in 1986 with the Toxicity Characteristic
Leaching Procedure (TCLP), due to constrains of the method related the characterization of organic pollutants
(Prange and Garvey 1990). Based on this method, TCLP concentrations are considered to be toxic, if they
exceed the Toxicity Characteristic (TC) limit. In this case WEEE is considered to be a hazardous waste
(Townsend 2011). Therefore, the amount of elements found in devices plays a major role in the toxicity
threshold limits (Lincoln et al. 2007; Vann et al. 2006).
However, EPA Science Advisory Board (SAB), advised the need to review the current TCLP procedure, in terms
of improvement and accuracy, (i) while it does not take into consideration broader range of affecting
parameters and (ii) because may over or under estimate the leaching results in different scenarios considered
as waste and site specific (Browner 1999).
Based on TCLP method, the toxicity characteristic is determined by experimenting the input material particle
size less than 10 mm (Method 1311, US EPA) without taking into consideration the metal concentration in
different ranges of the reduced particle size and variations of metal concentration results as shown in Prange
and Garvey (1990) study.
10
2.4 Simulation models and parameters to assess the leachable metal content
2.4.1 Simulation models
Models may predict the leaching of trace elements, based on the leaching of heavy metals (Halim et al. 2005).
One of the leaching models used to predict the leaching of heavy metals from cement-stabilized waste in the
presence of municipal waste landfill leachate is PHREEQC geochemical package used by Halim et al. (2005).
Even though is very difficult to develop a universal capable model due to the wide variation of leachate
characteristics, metal leaching may be predicted if the rate of composition and dissolution of waste can be
identified. Halim et al. (2005), presented the following schematic modeling algorithms (Figure 3).
Figure 3 Schematic diagram of trace elements leaching modeling (Halim et al. 2005)
Overall, the model evaluated the maximum release of constituents within the range on the system capacity under a period of time and under various environmental conditions (Halim et al. 2005). Crawford (1999), estimated that mechanisms such as availability or the amount of substances present, kinetics
and solubility can control the solubility and transport from solid to liquid phase. The solubility of Pb and Cd for
example is possible to be calculated through PHREEQH geochemical simulation program. Therefore their
release can be controlled by adding other minerals under oxidizing or reducing conditions as a function of pH.
Other programs and models used are GEOCHEM, MINTEQA2 / PRODEFA2 using Gaussian model for dissolved
organic matter – ligand models and WHAM used for binding with humic substances. The majority of trace
elements are soluble in the acidic pH ranges stable in the neutral to alkaline region. Therefore they may react
as acids and bases (Tipping 1994; Fletcher and Sposito 1989).
Meeussen (2003) used the modeling framework ORCHESTRA (Object Representation of Chemical Speciation
and Transportation models) to determine the chemical equilibrium calculations for speciation and transport of
trace elements in soil. This model differs from standard chemical equilibrium algorithm models like MINTEQA2
and PREEQC because it allows the modification of the source code by users (Figure 4).
11
Figure 4 Structure of ORCHESTRA framework in comparison with structure used in standard speciation programs (Meeussen 2003).
Based on the above modeling programs, Dijkstra et al. 2004, investigated leaching of heavy metals from
contaminated soil, combining the selective chemical extraction techniques with geochemical modeling. Based
on that, the ORCHESTRA framework and MINTEQA2 database were used for calculation of saturation indexes,
speciation and transportation of trace elements. Figure 5 presents the results of leached concentration and
model prediction as function of pH from different sample soils (Dijkstra et al. 2004).
Figure 5 Prediction of Leaching Test Data for contaminated soil by geochemical speciation
Test: PrEN 14429 (Dijkstra et al. 2004)
12
In general, the model predictions for leachability of trace elements are adequate except a number of cases
where models do not predict on high values of pH, which may show a decrease at pH:12 (Dijkstra et al. 2004).
2.4.2 Leach XS
The recent database Leach XS is used to characterize the materials and Environmental Impact Assessment (EIA)
and to estimate the release of substances of concern over a defined time period. This database covers
leaching/extraction test data coming from lab experiments and provides chemical speciation prediction model,
pH dependency prediction model and mass transport modeling. All above is integrated into the database by
using ORCHESRTA modeling and estimate the short and long term release (Sloot et al. 2004) (Figure 6).
Chemical speciation and pH dependent leaching prediction requires data on the leachable metal content as
function of pH, as well as data on precipitation/dissolution reactions. Mass transport modeling, requires the
leachable metal content as function of flow rate or percolation tests, as well as a variety of field conditions
such as starting and boundary conditions (Sloot, 2004).
Figure 6 Overview of Leach XS database (http://www.leaching.net/leaching/databaseexpert-system/)
Accessed: 20th August, 2014
2.5 Data on the leachable metal content from WEEE related fractions
Leaching behavior of trace elements can be performed through different tests simulating the environmental
conditions, taking into consideration differences in temperature, contact time, pH, oxygen availability etc.
Sequential extraction analyses are of major importance to provide information on the mineral phases and
chemical form of metals. Batch leaching tests have been used to simulate chemical reactions and deionized
waste extraction tests (DI) have been used to simulate rainfall conditions or buffering capacity (Al-Abed et al.
The above tests have been used to quantify the leachable metal content under different conditions such as pH
and redox potential as well as compare leaching of different metals in short term batch leaching tests. Total
metal concentration and sulfate analyses carried out using Inductively Coupled Plasma-Atomic Emission
Spectrometry (ICP – AES) and Ion Chromatograph respectively (Al-Abed et al. 2006; Chancerel et al. 2009).
Al-Abed et al. (2006), found that the leachable metal content is maximized in acidic pH region for cationic trace
elements like Cu, Pb, Zn. On the other hand, increasing pH leads to iron precipitation. Se mobility also
increases in alkaline conditions. Except Se, metal concentrations as a function of pH for Cu, Pb and Zn shows
the same shape as shown in Figure 7, where the acidic pH increases the mobility and leachability of the trace
elements. The results are performed in oxic conditions and pH range from 3 to 11 (Al-Abed et al. 2006).
Figure 7 Extract metal concentration from pH dependency test under oxic conditions
Note: the connecting lines between dots in the graph are meant to facilitate the readability and to visualize the V shape of cationic
mobility as function of pH
(Al-Abed et al. 2006)
From the research presented in Figure 7, around 46% of Cu mobility is increased at pH 3 and is decreased with
increasing pH, leading to precipitation of cations in neutral to alkaline conditions. The same is shown for Pb
and Zn. On the other hand, Se mobility is increased in the pH ranges from 5 to 11 (Al-Abed et al. 2006).
Li et al. (1999) have used landfill simulation in columns to evaluate the leachable metal content in the landfill.
Different tests have been performed mixing different type of electronic equipments with municipal waste,
such as column filled with a mixture of municipal solid waste (MSW) and cathode ray tubes (CRTs), or PCBs,
hard dick and floppy disc drivers, etc.
Li et al. (2009), reported that Pb concentration in the leachate was not detected, but in the solid phase
underneath WEEE was significantly detected. Therefore, it is estimated that Pb would enter the leachate after
a long term transport. On the other hand, all elements have been detected in the solid phase leading with the
highest concentration of Al due to the fact that PCs contain high amount of Al. The second highest is Fe
followed by Pb, Zn, Sn, etc (Li et al. 2009). Figure 8 shows an example of a landfill simulation column.
14
Figure 8 Schematic of landfill simulation column by mixing different types of electronic devices with municipal waste (Li et al. 2009)
Musson et al. (2000) reported that the majority of the lead in a typical computer is attributed to CRTs. Menad
(1999) estimated that there is more than 98% of metal composition in CRT is lead. Li et al. (2009) simulated the
worst case landfill scenario and showed from TCLP extractions at pH: 4.93 that Pb concentrations from PCBs
are between 150 – 500 mg/L exceeding the toxicity characteristic threshold limit of 5 mg/L. The average TCLP
leachate lead concentration versus iron content has been investigated. From the results, as shown in Figure 9,
devices with less amount of iron were most likely to exceed the threshold limits of Pb concentration than the
ones with higher iron concentration (Musson et al. 2006).
Figure 9 Average lead concentration versus the percentage of ferrous metal content for PCBs from 13 electronic devices in PCLP tests (Musson et al. 2006b)
The presence of Fe inhibits Pb release due to its potential oxidation potential. Also, the increase of Fe surface
area due to particle size reduction, decreases Pb mobility (Musson et al. 2000).
15
To conclude, as described above, different tests and experiments can be done in order to investigate the
leachable metal content in different environmental conditions, as well as investigating the main parameters
that affect the mobility of heavy metals such as pH, contact time, particle size and liquid to solid ratio (L/S),
presence of organic matter and complexation and binding with other metals.
2.6 Toxicity assessment of metal emissions
Different approaches have been made in Life Cycle Assessment, to assess the environmental and human
health impact of metal emission. Anthropogenic activities are the main contributors of increasing the metal
concentration in the environment by exceeding the natural level of these elements in the nature (D’Amore et
al. 2005). Therefore, life cycle assessment is used to estimate whether the amount of the emitted compounds
during the life cycle of the product, potentially affect human health and the environment (Haye et al. 2007).
Further, life cycle impact assessment (LCIA) is used to estimate the impact of the emitted compounds have in
human health of environment by multiplying the mass of the substance with characterization factor (CF) taking
in consideration the fate factor (FF) and the effect factor (EF) (Haye et al. 2007).
As showed earlier, some heavy metals such as Fe, Cu, Mg etc., are needed to some extend to the body,
whereas some others like As, Ba, Cd, Ni and Pb impose only risk exposure to human health (Pizzol et al. 2011).
Therefore, Pizzol et al., (2011) showed that the defined criteria are related mostly to inorganic elements and
their chemical speciation, non degradability and persistence onto the environment and human toxicity.
However, estimation of characterization factor and hazard classification for metals is difficult due to their
transformation or different forms of bioavailability in different sites (Meister et al. 2008).
Besides different methodologies and models used for LCIA, the new fate and exposure model harmonizing the
existing models is USEtoxTM. The environmental model USEToxTM, is used for characterization of human and
eco – toxicological impact of inorganic compounds based on the collected experimental data. Characterization
factors for specific inorganic compounds called “interim” for human toxicity, fresh water and coastal marine
water ecotoxicity can be calculated in the software database (Pizzol et al. 2011). For a better understanding,
the USEtox characterization factors are presented in ANNEX 1.
2.7 Environmental threshold values for metal emissions
2.7.1 Landfill acceptance criteria
Based on the landfill directive (EU 1999/31/EC), the wastes are disposed separately to inert, non hazardous
and hazardous landfills based on the so called “different classes’ acceptance criteria”. These criteria are
established by Council Decision 2003/33/EC and can be found at Annex II of the landfill directive EU
1999/31/EC. Based on Annex II of the landfill directive (EU 1999/31/EC), the procedure for the acceptance of
waste in landfill includes characterization for each type of waste, compliance of results with the acceptance
criteria as well as on site verification. The criteria are developed taking into consideration (i) the material
source of contaminant based on the constituent leachability over time and (ii) environmental scenarios based
on the migration of contaminant from the landfill to groundwater reaching the so called point of compliance.
16
Inert waste landfills (class 0) accept glass, concrete, bricks, soil etc., and non hazardous waste landfills (class I
and II) includes municipal and household waste. The above waste categories are accepted based on the limit
values without testing, whereas the limit values for the wastes accepted to hazardous waste landfills (class II
and III) are settled based on the waste liquid to solid partitioning leaching tests (2003/22/EC). Table 3
summarizes heavy metal acceptance limits for all landfill classes.
2.7.2 Surface water
Directive 2008/105/EC on environment quality standards in the field of water policy, set up maximum
allowable concentrations for 33 substances of concern including toxic metals such as Cd, Pb, Ni. The purpose of
this directive is to protect the quality of aquatic environment by chemical pollution in short and long term and
to prevent the aquatic life toxicity, accumulation in ecosystems and threat to human health.
Also, the water directive established a framework for the protection of surface and ground water. Surface
water directive (77/440/EC) determines three categories of surface waters where the discharge limits for
heavy metals are specified in Table 3. However the limits are established in order to transform the waters of
categories into drinking water. EU drinking water values based on the directive for drinking water (98/83/EEC)
are also presented in Table 3.
2.7.3 Groundwater
According to Dangerous Substance Directive 76/464/EEC, toxic elements are categorized in different lists
based on their level of toxicity in human health and environment. Cd for instance is considered a very toxic
element for surface and ground wasters because of its high affinity with organic matter. For this reason, it is
classified in the List I Substance of Annexes of Dangerous Substance Directive with restricted use in surface and
ground waters due to its risk to human health via fish. Based on this Directive, Cd is found in surface and
ground water through industrial discharges and landfill leachate (EPA, 2001). Cd is classified in the list of
hazardous element originating from WEEE alloys on Annex VIII of Basel Convention on transboundary
movement of hazardous waste.
Other elements such as Cr, Cu, Ni, Pb and Zn, are classified in List II Substance of Annexes of Dangerous
Substance Directive 76/464/EEC and List II Substance of Annexes of Groundwater Directive 80/68/EEC, with
restricted use in ground waters. Based on this directive, Cu and Zn toxicity depends on the hardness of the
water concerning the aquatic environments and to human health if their concentration exceeds certain limits.
Ni is an element of concern in plants and aquatic environment due to its toxicity to fish, but limited in human
health risk. Pb is considered toxic because of its accumulation in body tissue. Pb is classified in the list of
hazardous elements originating from WEEE alloys, on Annex VIII of Basel Convention on transboundary
movement of hazardous waste.
Table 3 presents a summary of all above mentioned about environmental threshold values for metal
emissions.
17
Table 3 EU mandatory limits for toxic elements including the acceptance criteria for disposal of waste into landfills and European discharge limit values in soil, surface water and drinking water.
Heavy Metals
EU regulatory limit
L/S 10 L/kg pH: 5.5 -13
(mg/kg)
European Heavy Metal limit values
in soil pH 6 – 7(1)
(mg/kg dry matter)
Mandatory Value in EU
Directives for surface water(2)
(mg/L)
Classification EU Directives for ground water(3)
(mg/L)
Mandatory Value in EU Directive for
drinking water(6)
(mg/L) Class 0 - I
Class II – III - IV
Pb 0.5 10 – 50 50 - 300 0.05 List II substance(4) 0.01
Zn 4 50 – 200 150 - 300 3 – 5 List II substance 5
Cu 2 50 – 100 50 - 140 0.05 – 1.0 List II substance 2.0
Cd 0.04 1 – 5 1 – 3 0.005 List I substance(5) 0.005
Ni 0.4 10 – 40 30 - 75 - List II substance 0.02 (1) Data collected from Directive 86/278/EEC, of 12 June 1986. (2) Surface Water Directive (77/440/EEC) / 1989 Regulations. (3) Ground Water Directive (80/68/EEC). (4) Pb, Zn, Cu, Ni, Cr fall under List II (the “grey list”) substance of Dangerous Substances Directive (76/464/EEC), which authorizes the discharge limits for this category and List II substances of ground (5) (6) Cd falls under Appendix 6, List I (the “black list”) discharge category of Dangerous Substances Directive (76/464/EEC) and List I substances of ground water directive 80/68/EEC. (5) List I includes dangerous elements based of their toxicity, persistence and accumulation (Directive 76/464/EEC and Directive 80/68/EEC). water directive 80/68/EEC for substances that impose harm to aquatic environments (Directive 76/464/EEC and Directive 80/68/EEC). (6) Drinking Water Directive (98/83/EEC).
18
CHAPTER III
3. MATERIALS AND METHODS
3.1 Overview of experimental design
The purpose of the experimental work was to quantify the release of heavy metals from WEEE under defined
conditions from different matrices. Experimental conditions are varied to access the metal release.
PCB < 10 mm, shredder fluff and Li-ion Battery ash were used as experimental matrixes. Nine metals, which are
mainly found in the material matrices are selected as lead metals such as Fe, Co, Ni, Cu, Zn, Cd, Ba, Pb and As.
Experimental procedures follow the European Committee of Standardization (CEN) related to pH
characterization tests (CEN/TS 14429) and standardized batch leaching tests (EN 12457 1-4). All experiments
are carried out in triplicate measurements for all input materials. Parameter values measured include pH, Eh,
Ec, DOC and heavy metal concentrations for cations Fe, Co, Ni, Cu, Zn, Cd Ba, Pb and As, as well as for anions
such as chlorides and hydroxides. Figure 10 presents an overview of experimental set-up related to leaching
test results.
Figure 10 Overview of experimental set up including the research questions to be answered based on the leaching results
19
3.2 Origin and description of the input materials
Three input matrices are investigated for the purpose of this study. PCB and shredder fluff, originate directly
from a plant processing Waste Electric and Electronic equipment for the categories 2, 3, 4, 6, 71 according the
Directive 2012/19/EU. The material input consist particularly of small household appliances (category 2) which
are considered to have low content of precious metals in the printed circuit boards.
The primary sampling procedure consist of the manual separation of different appliances such as cables,
motors, switches, etc. and feed to shredding where fluff – the first input matrix of this study – is collected with
Zick-Zack air classifier. Ferrous metal product collector has been done by magnet separation. Printed circuit
boards (PCBs) – the second input matrix of this study – are separated with a color sorting processing machine
which separates PCBs from metal and plastic fractions with induction separator, obtaining the final printed
circuit board product.
The third input matrix consists of residues from the thermal treatment of lithium ion batteries. Primary and
secondary cells are incinerated in a rotary kiln for 30-45 min at around 8500C. After the incineration the
residues pass a water bath in the wet deslagging unit. The material passes via a conveyor belt a flat screen
where larger metal pieces are screened off at 30mm.
The secondary sampling procedure consist of fluff sieving with particle size less than 10 mm and PCBs crushing
with a big shredder (MeWa – UNI – CUT UG – Granulator) with cutting size 40 mm and then further shredded
with small shredder (Retsch Hammer mill) with cutting size 10 mm. The primary and secondary sampling
procedure for Li-ion battery ash is presented schematically in ANNEX 2.
The test samples for each experiment are homogenized based on the mass distribution of each sieve fraction.
Figure 11 shows the grading curve based on the cumulative mass passing in percentage of weight fraction for
all materials. The mass distribution calculation for each input material including the net material weight and
the percentage by weight for PCBs, shredder fluff and Li-ion battery ash are shown in ANNEX 3.
1 Cat definition: 2) Small household appliances 3) IT and telecommunications equipment 4) Consumer equipment and photovoltaic panels 6) Electrical and electronic tools (with the exception of large-scale stationary industrial tools) 7) Toys, leisure and sports equipment
20
Figure 11 Grading curve for PCB < 10 mm, shredder fluff and Li-ion Battery ash testing matrices
3.3 Leaching test procedures
3.3.1 pH controlled leaching test (CEN/TS 14429)
The test is performed on characterization of waste, based on the influence of pH on leaching with initial
acid/base addition and liquid-solid (L/S) ratio 10. This test has been performed for three matrices PCB < 10
mm, shredder fluff and Li – ion battery ash.
Titration procedure is used for acid/base neutralization capacity by adding 1M HNO3 for acidic conditions and
1M NaOH for basic conditions. Titration procedure includes ranges of pH from 3 to 12 and is applied for PCBs ˂
10 mm, shredder fluff and Li – ion batteries. The quantity of input material is distributed at each 1 liter plastic
bottles labeled with pH 3; 4.5; 6; 7.5; 9; 10.5 and pH 12 with 8 pH ranges, respecting the difference of 1.5 pH
units between two ranges.
A test portion of input material is weighted and dried at 1050C and the dry residue is then calculated. The test
portion calculations in terms of input material and leachant calculations for pH dependency test for three input
matrices PCB < 10 mm, shredder fluff and Li – ion battery ash are found in ANNEX 4.
The mass used for the experiment is 60 g for each bottle with L/S 10. The leachant is added in three steps: 1/3
in time zero, the second 1/3 portion after 30 min rotation and the last 1/3 portion after 2 hours of rotation. pH
is recorded based on three stages: after 4 hours of rotation where all volume is added to the bottles, after 44
hours of rotation, until reaching the equilibration period and after 48 hours of rotation, which is the
verification or the saturation period. Figure 12 shows an example of the test for PCB < 10 mm. The same
procedure is followed for shredder fluff and Li – ion battery ash.
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0.1 1 10
Pe
rce
nta
gep
assi
ng
Sieve size (mm)
PCB < 10 mm
Shredder fluff
Battery ash
21
Figure 12 pH dependency test for input waste matrices at L/S 10 l/kg and contact time 48 hours
Final pH records after 48 hours of rotation for each material are shown in Table 4.
Table 4 Final pH records after 48 hours of rotation for pH dependency test for PCB < 10 mm, shredder fluff and Li-ion batteries
Required pH Recorded pH
PCB < 10 mm Shredder fluff Li – ion battery ash
3 3.8 3.47 3.75
4.5 5.52 4.2 4.44
6 6.2 6.35 6.14
7.5 7.16 7.51 7.57
9 8.9 9.58 8.4
10.5 10.2 11.19 10.35
12 11.35 12.26 12.56
3.3.b LS dependency test (EN 12457)
The test is performed in order to characterize the waste, based on the influence of a range of liquid-solid
ratios over a period of 72 hours. This test has been performed in triplicate measurements for PCB < 10 mm and
Li – ion battery ash and shredder fluff.
The test leachant portion applied is 80 ml for all samples according to the standard whereas the weight of the
test portion prepared is 8 g; 16 g; 40 g; 80 g and 160 g based on the calculated L/S ratio 10; 5; 2; 1 and 0.5 L/kg
dry weight respectively. The experiment is carried out in room temperature around 200C. A summary of test
portion calculations is presented in ANNEX 4. Samples are rotated for 72 hours using a rotary tumbler at 15
rpm.
3.4 Eluate sample preparation
The eluate sample preparation is the same for all experiments. After rotation with rotary tumbler, samples are
allowed to settle for 15 min for liquid solid separation and the eluate is passed first through glass fiber filters
(GF 6 – Whatman GmbH) Ø 47 mm. pH, Eh, Ec are recorded immediately and the eluate is passed through 0.45
22
µm pore size cellulose acetate filters. Figure 13 gives an example of the filtered samples before they are used
for TOC and ICP-MS measurements.
Figure 13 Filtered samples after second filtration with 0.45 µm pore size cellulose acetate filters
The blank eluate is carried out with a leachant volume of 0.95L and all the eluate procedures are followed the
same as above except the sieving and fractionation and mixing with waste material.
Portions of filtered eluate are used for DOC measurements, measurements of Cl- by titration and metal
concentration.
3.5 Analytical procedure
Parameters such as pH, redox – potential (Eh) and electrical conductivity (Ec) are measured with a mobile pH
meter model 691 Metrohm, Eh meter Cond 3310 and Ec meter WTW 323.
Dissolved Organic Carbon (DOC) is measured with a Total Organic Carbon (TOC) Analyzer that consists of
removing inorganic carbon with acid and oxidizing the remaining carbon in order to measure the generated
CO2 (Benner and Hedges 1993; Kolka et al. 2008). Kolka et al. (2008) defined DOC as organic molecules that
pass through a membrane filter with pore size 0.45µm. For eluate filtration, 0.45 µm cellulose acetate filters
are used, giving the fact that they do not release any additional DOC during filtration.
Metal concentration is determined by Inductively Coupled Plasma Spectrometry (ICP – MS) (Thermo XSeries 2)
whereas chloride concentration is determined by titration (Titrino 848 Metrohm).
All experimental results for metal concentration measurements using TOC analyser, Cl- Titrino and ICP-MS are
provided in mg/L. The final results for pH dependency test and L/S dependency test are converted in mg/kg dry
matter. Based on the standard CEN/TS 12457 the conversion takes into consideration the dry mass of the
material used based on the formula:
A = C x [(L/MD) + (MC/100)]
where:
A – metal release in (mg/kg dry matter) C – metal concentration in (mg/L)
23
L – leachant volume (L) MC – moisture content (%) MD – dry mass of the test portion (kg)
3.6 Total Metal Content
Samples from all input material are ground a planetary ball mill (Retsch PM 400). The residues are grinded with
Ultra Centrifugal Mill (Retsch UZM). The digestion is made with a microwave. Aqua regia 96 ml HCl and 32 ml
HNO3 has been used to extract the metals from the input material. The mass of each sample is 0.25 g. The
extraction is done in triplicate experiment for each material. The microwave cups are used to mix 0.25 g of dry
mass sample and 10 ml aqua regia and leaved open for 90 min. After, they are closed and put in microwave
running with 100% power 1,200 watt, pressure 20 bar and temperature 2000C for 15 min. After cooling down,
the digestat was put in a blue ribbon filtered and flushed with 0,5 M HNO3. A 25 ml beaker glass is used for the
mixing the extract with 0.5 M HNO3 and stored in fridge. The measurement of total metal content is done with
Chemical speciation modeling data are the first step preparation for pH dependency solubility prediction
model. pH dependency prediction model measures the leaching behavior of constituents taking into
consideration all possible mineral formation based on the experimental data collected from tests results.
Orchestra geochemical modeling is used to calculate the prediction equations and the possible dissolution and
sorption reactions. Predictions are carried out for metal solubility as function of pH as well as liquid – solid
partitioning of metals taking into consideration the chemical speciation (Seignette et al. 2013).
3.9 Toxicity assessment
USEToxTM is used to assess environmental impact of the metal release. USEToxTM, is a scientific consensus
environmental model used for characterization of human and eco – toxicological impact of inorganic
compounds based on the collected experimental data. Characterization factors for specific inorganic
compounds called “interim” for human toxicity, fresh water and coastal marine water eco-toxicity can be
calculated taking into account the fate and exposure of inorganic constituents in life cycle impact assessment
(Mckone et al. 2010).
Based on the USEtox guideline prepared by Mckone et al. (2010), the total impact of an emission can be
calculated according to:
𝐼𝑆 = 𝐶𝐹𝑥 ,𝑖 ∙ 𝑀𝑥 ,𝑖
𝑥𝑖
IS impact score for e.g. human toxicity (cases)
CFx,i characterization of substance “x” released to compartment “i” (cases/kg)
Mx,i emission of “x” to compartment “i” (kg)
The characterization factors are calculated based on the inorganic substance database (21 metals and metal
species), including three types of datasets: (1) physicochemical properties, (2) toxicological effect data on
laboratory animals as a surrogate to humans, and in rare cases toxicological effect data on humans, and (3)
ecotoxicological effect data for freshwater organisms. The model variables are landscape data that determine
the fate and exposure. USEtox defines agricultural and natural soil, fresh and coastal marine water as
emissions compartments.
The leachable content is either fully emitted to fresh water (Scenario 1) or fully emitted to coastal marine
waters (Scenario 2). The leachable content under L/S 10 at the neutral pH (moderate scenario) and the
leachable content at pH 3 (extreme scenario) are defined as Leaching Scenarios. This relation is presented in
Table 6. Characterization factors are calculated on the basis default values of the USetox landscape data. The
calculated USEtox characterization factors are presented in ANNEX 1.
26
Table 6 Example of Scenarios for leachable content at L/S 10 under neutral pH called moderate scenario and pH 3 called extreme scenario and their emission to fresh and marine coastal water
Scenarios for Scenarios for leachable content
L/S 10 pH3
Emission to Fresh water Human toxicity total
Eco toxicity
Emission to coastal marine water
Human toxicity total
Eco toxicity
As mentioned earlier, all characterization factors effects for the inorganic group are specified as “interim”, due
to relatively high uncertainty associated with estimates of fate, exposure and effect of constituents. This
means that these are only indicative values. Nevertheless it is an approach for a first screening of the relevance
of various metals or various materials against each other (Mckone et al. 2010).
27
CHAPTER IV
4. RESULTS
This chapter provides an overview of the results of leaching experiments for PCB, shredder fluff and Li-ion
battery ash. It displays the results of the experiments conducted so as to achieve the objectives.
4.1 Quantification on the leachable metal content from WEEE related residues under selected
test conditions
4.1.1 Part of mobilized metal content under the specific conditions to enhance mobilization
Specific tests have been performed in order to investigate the metal mobilization. The full results are shown in
ANNEX 5 incorporating the table of the leachable metal content from pH dependency test and L/S dependency
test.
In summary, the total metal content show that the highest concentration remain for Cu found in PCBs with 14
± 2% of dry weight, while for shredder fluff and Li-ion battery ash, Cu remain for 1.8 ± 0.2% and 4.2 ± 0.04%
respectively. Zn is found with 1.8 ± 0.02%, 1.06 ± 0.09% and 0.2 ± 0.08% dry weight for PCB, shredder fluff and
Li-ion battery respectively. Meanwhile Fe, remain for 1.6 ± 0.28%, 2.4 ± 0.14% and 10.5 ± 0.2% dry weight for
PCB, shredder fluff and Li-ion battery respectively.
Pb and Cu are the main specific metals for PCBs, Cd and Ba for shredder fluff and Fe, Ni, Co and As for Li-ion
battery ash.
Total metal concentrations are found as shown in Figure 14 for three types of WEEE. In general, Fe, Zn and Cu
are the most abundant metals in three materials.
Figure 14 Total metal content of nine metals from PCB < 10 mm, shredder fluff and Li-ion battery ash input material (n=3) (aqua regia digestion of the original test material ground to < 0.5mm)
1
10
100
1000
10000
100000
1000000
Fe Co Ni Cu Zn Cd Ba Pb As
Tota
l me
tal c
on
ten
t (m
g/kg
)
Aqua Regia extraction
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
28
As shown in Figure 15, the leachable metal content is at pH 3 is around 10 times lower compared to total metal
content whereas at L/S 10 L/kg is around 5000 to 10,000 times lower compared to total metal concentration.
In general, there are some sizable difference between materials and metals.
Figure 15 The leachable metal content from L/S dependency test at L/S 10 L/kg and pH dependency test at pH 3, from PCB < 10 mm, shredder fluff and Li-ion battery ash
The leachable metal content results higher at pH 3 compared to natural pH at L/S 10 l/kg. The results above
show that the most pronounced dependency is pH. Figure 16 show the leachable metal release as function of
pH.
0.01
0.1
1
10
Fe Co Ni Cu Zn Cd Ba Pb
Leac
hab
le m
eta
l co
nte
nt
(mg/
kg)
L/S 10 (l/kg)
PCB < 10 mm (pH 4-5)
Shredder fluff(pH 8)
Li-ion Battery ash(pH 10)
Detection limit 0.02 mg/kg
0.001
0.01
0.1
1
10
100
1000
10000
Fe Co Ni Cu Zn Cd Ba Pb As
Leac
hab
le m
eta
l co
nte
nt
(mg/
kg)
pH 3
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
Detection limit for As 0.01 mg/kg
Detection limit 0.02 mg/kg
29
Figure 16 The leachable metal content from three different material such as Li-ion Battery ash, PCB < 10 mm and Shredder fluff as function of pH, at L/S 10 (l/kg), after 48 hours contact time
4.1.2 The influence of sample matrix and its chemical composition on the metal leaching
As shown in Figure 17, arranged vertically for different materials, Cu is the most abundant element with higher
percentage in PCBs followed by shredder fluff and Li-ion battery ash. Cu shows also the highest concentration
at L/S 10 for all the materials. Meanwhile for Pb, the results from pH dependency test (pH3), show that Pb is
leached more from shredder fluff and PCB < 10 mm, whereas Ni is leached more from Li-ion battery.
detection limit
0.001
0.01
0.1
1
10
100
1000
2 4 6 8 10 12 14
Rele
ase
(m
g/k
g)
pH
Cd
detection limit
0.001
0.01
0.1
1
10
100
1000
2 4 6 8 10 12 14
Rele
ase
(m
g/k
g)
pH
Cu
detection limit
0.001
0.01
0.1
1
10
100
1000
10000
2 4 6 8 10 12 14
Rele
ase
(m
g/k
g)
pH
Pb
detection limit
1E-03
1E-01
1E+01
1E+03
1E+05
2 4 6 8 10 12 14
Rele
ase
(m
g/k
g)
pH
Zn
detection limit
0.001
0.1
10
1000
2 4 6 8 10 12 14
Rele
ase
(m
g/k
g)
pH
Ni
30
Figure 17 Relative share of nine lead metals in PCB, shredder fluff and Li-ion battery ash for the total metal content (aqua regia digestion) and metal release from L/S dependency test (L/S 10 l/kg) and pH dependency test (pH 3)
The sum of the nine lead metals in mg/kg for the three materials and three tests is shown in Figure 18.
Figure 18 Relative share of nine lead metals and the leachable content for three materials and tests together in PCB, shredder fluff and Li-ion battery ash for the total metal content (aqua regia digestion)
PCB < 10 mmtotal content (mg/kg)
Ba Cd Co Cu
Shredder fluff total content (mg/kg)
Ba Cd Co CuNi Pb As
Li-ion Battery ash Total content (mg/kg)
Ba Cd Co Cu Ni Pb As
PCB < 10 mmMetal release at L/S 10 L/kg
Ba Cd Co Cu Ni Pb
Shredder fluffMetal release at L/S 10 L/kg
Ba Cd Co Cu Ni Pb
Li-ion battery ashMetal release at L/S 10 L/kg
Ba Cd Co Cu Ni Pb
PCB < 10 mmMetal release at pH 3
Ba Cd Co Cu Ni Pb
Shredder fluffMetal release at pH 3
Ba Cd Co Cu Ni Pb
Li - ion Battery ashMetal release at pH 3
Ba Cd Co Cu Ni Pb
Total content
Ba Cd Co Cu Ni Pb
L/S 10 (l/kg)
Ba Cd Co Cu Ni Pb
pH 3
Ba Cd Co Cu Ni Pb
31
Overall, Cu is the most abundant element in three materials, Pb is the most leached one at acidic condition and
Cd and Pb are the most leachable metals from L/S 10 (l/kg).
The eluate pH recorded after 72 hours of rotation for Li-ion battery ash is at around pH 10, shredder fluff at
around pH 8 and PCB < 10 mm at pH range of 4 to 5.5. The relation pH as function of L/S ratios after 72 hours
of rotation is shown in Figure 19.
Figure 19 The relation of pH as function of L/S ratio from Li-ion battery, Shredder fluff and PCB < 10 mm at L/S 10, 5, 2, 1 and 0.5 (l/kg) and for 72 hours contact time
Based on the above pH results, hydroxides are calculated in order to investigate metal precipitation as
hydroxides. Chloride precipitation is also observed. The ion activity product for different elements shows that
no hydroxide precipitation occurs for PCB < 10 mm because of the low eluate pH. Cu precipitates as Cu(OH)2
from shredder fluff and Li-ion battery ash as well as CuCl from Li-ion battery ash, showing lower concentration
at L/S 10 compared to other materials. Pb precipitates as Pb(OH)2 from shredder fluff. A detailed table of
calculations for hydroxide and chloride precipitations for all tests can be found in ANNEX 5.
In terms of DOC, when comparing the three input materials, it is noticed that the level of dissolved organic
carbon (DOC) is relatively higher from shredder fluff and PCBs compared to Li-ion battery ash. These records
are 3,467 ± 46 mg/kg for shredder fluff, 962.2 ± 90.3 mg/kg for PCB < 10 mm and 94 ± 9 mg/kg for Li-ion
battery ash at the same experimental conditions at L/S 10.
As results suggest, metal availability and composition is different for different materials. Different factors, such
pH, presence of hydroxides and chlorides and DOC, may influence sorption, dissolution and precipitation and
affecting metal mobility. It is observed that low pH enhance Pb mobility, whereas natural pH gives more room
to Cu to leach. However, when three materials are together, metal composition differs and may contribute to
a different leachable content. Pb and Cd for instance are the most abundant metals when summing up the
materials at L/S 10, whereas separately the most abundant metal is Cu for the three materials.
0
2
4
6
8
10
12
0.1 1 10 100
pH
L/S (l/kg)
pH as function of L/S
Li-ion Battery ash Shredder fluff PCB < 10 mm
32
4.2 Metal behavior under given environmental conditions. Prediction of metal release based
on geochemical modeling
Prediction model is used to characterize the materials with limited tests, taking into consideration all necessary
factors that impact metal behavior under specific environmental conditions. Results obtained from Leaxh XS
software takes into account chemical speciation prediction model as a pre-phase of pH dependency prediction
model. Chemical speciation is run by ORCHESTRA geochemical modeling and the results show that Cu, Ni, Pb
and Zn may precipitate or form minerals mainly in alkaline region. Table 6 shows metal mineral formation for
each material and their respective pH.
Table 7 Model predicted mineral formation under specific environmental conditions
Material Element Mineral pH
Li-ion Battery ash Cu Atacamite Tenorite Cu[OH]2
6.14 & 8.4 7.57 & 10.35 8.4 & 12.56
Ni Ni[OH]2 7.57, 8.4 & 10.35
Pb Plgummite Plumbogummite Pb[OH]2
6.14 6.14 10.35 & 12.56
Zn Franklinite Faustite Zincite Zn[OH]2
3.75 6.14 10.35 & 12.56 12.56
Shredder fluff Cu CuprousFerrite Tenorite
6.35 & 11.9 12.26
Ni - - Pb - -
Zn Franklinite Zincite
3.47 7.51 & 12.26
PCB < 10 mm Cu Tenorite 11.34 Ni Ni[OH]2 11.34 Pb PbMoO4 3.8 Zn - -
All the results from the experimental set up, are the base of the input data for the database. The input
information consist of the leachable metal content for pH dependency test, and all other analytical results such
as conductivity, redox potential, pH.
pH dependency prediction model shows the leaching behavior of constituents taking into account the possible
mineral formation, co-precipitation with Fe, Al and Mn oxides, bounding with DOC and particulate organic
matter (POM). Orchestra geochemical modeling is running to calculate the prediction equations and the
possible dissolution and sorption reactions. Prediction results are presented in Figure 20 and show metal
solubility as function of pH in comparison with pH dependency leaching test results for three input materials.
However, model does not predict the leachability of some metals at pH 12. For Zn and Pb from PCB < 10 mm
for instance, no mineral is found from the database at high pH, which might also be the reason why the
33
prediction shows increase and the concentrations of Zn and Pb show decrease. However the prediction for Ni,
Zn and Cu show a good match with the experimental data and further discussed at section 5.2.
0.0001
0.001
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Cu+2]
0.0001
0.001
0.01
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Ni+2]
0.0001
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Pb+2]
0.01
0.1
1
10
100
1000
10000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Zn+2]
0.001
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Cu+2]
0.001
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Ni+2]
0.001
0.01
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Pb+2]
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Zn+2]
34
Figure 20 pH depencency prediction modelling results for inorganic constituents in comparison with pH dependency leaching test results for three input materials Li-ion Battery ash, shredder fluff and PCB < 10 mm.
Prediction results for liquid–solid partitioning of metals materials are attached to ANNEX 7.
4.3 Compliance of metal emissions from three materials with emission and criteria
This section show the normalized results based on the calculated ratio between the leachable metal content
and the EU acceptance criteria and heavy metal discharge limit into soil.
Specifically, Figure 21 show the normalized results for the leachable metal content at L/S 10 (l/kg) compared to
the EU acceptance criteria for disposal of WEEE in hazardous waste, Class III (landfill directive EU 1999/31/EC
and Council Decision 2003/33/EC). The results show that all metals are within the acceptance limit for dispose
to hazardous waste landfills, except DOC which is exceeding the normalized relative value > 1. Therefore,
except DOC, the hazardous waste landfill can be an option for disposing the WEEE when the leachable metal
content is measured under natural pH.
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Cu+2]
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Ni+2]
0.001
0.01
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Pb+2]
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Zn+2]
35
Figure 21 The normalized results for the leachable content at L/S 10 (l/kg) compared to the EU acceptance criteria for disposal of WEEE in hazardous waste, Class III, Li-ion battery ash, shredder fluff and PCB < 10 mm from L/S dependency test (EN 12457-4)
Figure 22 presents the comparison between the total leachable content and EU acceptance criteria for waste
disposal to underground landfill of hazardous waste. All metal concentration exceed the limits of disposal of
this material into underground hazardous waste landfill based on the EU acceptance criteria for landfill class
IV. Therefore the underground waste disposal cannot be an option giving the fact that the metal concentration
is too high.
Figure 22 The normalized results for the leachable total content with aqua regia extraction compared to the EU acceptance criteria for disposal of WEEE into underground landfill of hazardous waste, Class IV, for Li-ion battery ash, shredder fluff and PCB < 10 mm
Figure 23 show the normalized results for the leachable content at L/S 10 (l/kg) compared to the threshold
limit values for soil (Directive 86/278/EEC) for neutral pH 7. The figure presents only the lower limits for L/S 10
0.001
0.01
0.1
1
10
Pb Cd Cu Ni Zn DOC
No
rmal
ize
d v
alu
e
L/S 10 (l/kg)
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
Normalized limit 1
0.1
1
10
100
1000
10000
Pb Cd Cu Ni Zn
No
rmal
ize
d v
alu
es
Total content
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
Normalized limit 1
36
(l/kg) giving the fact that the normalized values are within the threshold values and the only the higher limits
for total metal content giving the fact that the normalized values are exceeding the threshold limits.
Figure 23 The normalized results for the leachable metal content and total metal content compared to lower and upper threshold limits for soil for Li-ion battery ash, shredder fluff and PCB < 10 mm
As above, the results indicate that the leachable metal content comply with the hazardous waste landfills
acceptance limits under natural pH at L/S 10 (l/kg), but does not comply even with class IV of underground
waste disposal when we investigate the total metal content. The same falls for soil thresholds where the
material impose risk to soil contamination giving the fact that total metal content exceeds even the highest
limits of soil threshold values.
0.0001
0.001
0.01
0.1
1
Pb Cd Cu Ni Zn
No
rmal
ize
d a
lue
s w
ith
low
lim
its
L/S 10 (l/kg)
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
Normalized limit 1
0.1
1
10
100
1000
10000
100000
Pb Cd Cu Ni Zn
No
rmal
ize
d v
alu
es
wit
h h
igh
lim
its
Total content
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
Normalized limit 1
37
4.4 Most relevant toxic metals released from disposal of WEEE
In order to assess the metal release relative to its environmental impact, a toxicity assessment has also been
undertaken for six elements (Cu, Ni, Pb, Ba, Cd and Co) that may pose risk to environment and human health.
The analysis has been performed using the environmental model USEToxTM for the three input materials from
pH dependency test at pH 3 and L/S dependency at L/S 10 L/kg. Results show that Cu, Ni and Pb leached out
mainly from pH dependency test at acidic pH 3 pose risk to human health and the environment through their
release in fresh and coastal marine waters, whereas Ba, Cd and Co mainly to the environment.
Figure 24 presents the relative release of metals of concern and their relative impact on human health and
environment. It displays the most toxic element from three different materials under specific conditions. The
results for pH 3 and L/S 10 show that all elements pose risk either to human health or environment, except the
metal concentration leached out from Li-ion battery ash at L/S 10, which do not show toxicity to human health
or environment.
However their total content does pose risk to human health and environment. Cd and Pb is shown to pose risk
to fresh water and marine water, whereas Cu and Ni poses risk to human health. The same result is shown for
shredder fluff and PCB < 10 mm.
Li-ion Battery ash
Shredder fluff
Li-ion Battery ashRelease of toxic compounds
at pH 3
Ba Cd Co Cu Ni Pb
Li-ion Battery ashHuman toxicity total
Cu Ni
Li-ion Battery ashEcotoxicity
Ba Cd Co Ni Pb
Shredder fluffRelease of toxic compounds
at pH 3
Ba Cd Co Cu Ni Pb
Shredder fluffHuman toxicity total
Cu Ni Pb
Shredder fluffEcotoxicity
Ba Cd Co Ni Pb
38
PCB < 10 mm
Figure 24 Relative toxicity contribution of Ba, Cd, Co, Cu Ni and Pb, lead metals for two release scenarios, pH dependency test (pH 3) and L/S dependency test (L/S 10 L/kg) for human toxicity and ecotoxicity
Shredder fluffRelease of toxic compounds at
L/S 10 L/kg
Ba Cd Co Cu Ni Pb
Shredder fluffHuman toxicity total
Cu
Shredder fluffEcotoxicity
Ba Pb
PCB < 10 mmRelease of toxic compounds at
pH 3
Ba Cd Co Cu Ni Pb
PCB < 10 mmHuman toxicity total
Pb
PCB < 10 mmEcotoxicity
Ba Cd Co Pb
PCB < 10 mmRelease of toxic compounds at
L/S 10 L/kg
Ba Cd Co Cu Ni Pb
PCB < 10 mmHuman toxicity total
Cu
PCB < 10 mmEcotoxicity
Ba Co
39
CHAPTER V
5. DISCUSSION
5.1 Quantification of the specific release of metals from WEEE related treatment residues
under selected test condition
This study is focused on metal release from PCBs, Shredder fluff and Li-ion battery ash under selected test
conditions such as pH, liquid to solid ratios. It investigates the release of toxic metals from three input
materials, as well as their potential risk to human health and environment. Although certain elements such as
Co and Cu are to some extend needed to the body with certain concentrations, the rest of heavy metals such
as Ba, Cd, Ni, Pb and As impose risk to human health (Pizzol et al. 2011).
5.1.1 Assessment of environmental factors influencing metal emission
The environmental factors may play a role in the mobilization the toxic metals and their migration to fresh
water and seawater. Therefore to better understand the metal mobility in the environment, it is essential to
identify the impact scenarios derived by solubility and transport mechanisms through different processes such
as biological, chemical and physical.
Heavy metals commonly found in the landfill waste composition are Fe, Cd, Pb, Hg, Cu, Zn and Ni (Bozkurt et
al. 2000). In general, the highest metal concentration in the leachate is obtained during the waste degradation
acid formation stage, whereas methanogenic stage occurs under anaerobic conditions where pH is increased
between 6 to 8. At these pH ranges, the present metals usually precipitate as carbonates, hydroxides, and
phosphates and insoluble sulphides (Sang et al. 2012).
Open dumpsites in opposition to landfills, are composed of unsorted waste and are exposed continuously to
atmospheric conditions such as rainfall and differences in temperature. These affect also the abovementioned
processes that occur in landfill. Also, the majority of heavy metals in landfills is retained by Mn and Fe oxides,
adsorbed by organic matter and further down precipitate as carbonates, hydroxides, phosphates, silicates and
sulfides, minimizing this way the heavy metal mobility. In open dumpsites, this mechanism can be interfered
by oxygen penetration into layers, enhancing metal mobility by diffusion to areas with low concentrations
(Sang et al. 2012). Sulphide precipitation may be affected by oxidation of metal sulphides, which lead to metal
release as well as metal dissolution from carbonates due to pH decrease (Bozkurt et al. 2000). Such
mechanisms, pose also risk to the environment and public health (Prechthai et al. 2008; Sang et al. 2012)
However, this is difficult to generalize when taking into consideration the heterogeneity of the dump sites.
Therefore, a more profound investigation can be performed in the laboratory scale taking into consideration
landfill conditions, so that metal characteristics, their mobility, solubility, leached concentrations and their
impact on the diffusion of constituents to freshwater and seawater are analyzed in more detail.
For instance, in order to understand the metal composition of waster material, the total metal content has
been investigated. The results show that, Cu and Pb are the most abundant metals found in PCBs compared to
other materials with total content 141,798 ± 18,877 mg/kg and 9,044 ± 890 mg/kg respectively. Khandpur
(2006) showed that the majority of conductive layers on a PCB laminate are made of copper because of its
availability and low cost. Also, 36 percent of solder alloys are made of Pb and Sn and they may also contain Zn
40
and Cd (Khandpur 2006). Co and Ni are found in high concentration from Li-ion battery ash due to composition
of their cathode material (Kang et al. 2013). Co and Ni concentration are recorded 5,827 ± 46 mg/kg and
24,045.8 ± 1,403.6 mg/kg respectively. Other metals such as Fe and Zn are also found in high concentration in
all materials.
For investigating metal mobility, the simulation of worst case scenarios in laboratory scale has been applied
with pH dependency and liquid to solid dependency tests. As shown from the results, metals are available at
extreme conditions such as pH 3 and L/S 10 L/kg. This goes in line with landfill processes and other findings in
the literature, which report that the highest metal concentration in the leachate is obtained during the waste
degradation acid formation stage (Sang et al. 2012). Also, Lee et al. (2006) showed that metals are desorbed
from solid to liquid phase when decreasing the wet-dry cycles. Based on this, desorption is more difficult when
decreasing L/S ratios. This might explain why metal release is maximized at higher L/S ratios. The maximum
metal concentrations leached out under the simulated conditions are presented in Table 8 and are compared
with European limits for surface and drinking water.
Table 8. Maximum metal concentration from pH dependency test at pH 3 and L/S dependency test, regardless of liquid to solid ratios and European limits for surface and drinking water.
Name Maximum Metal Concentration pH 3 (mg/L)
Maximum Metal Concentration L/S dependency(4)
pH: 5 - 8 (mg/L)
Open dump leaching metal Concentration pH: 6.5 - 8 (mg/L)
(1) Li-ion Battery ash, (2) PCB < 10 mm, (3) Shredder fluff (4) Maximum concentrations from L/S dependency test regardless of L/S ratios (5) (Adedeji & Olayinka 2014); (6) (Olarewaju 2012); (7) Source: (Sewwandi et al. 2012); (8) (Mor et al. 2006); (9) (Gorchev & Ozolins 1984); (10) Drinking Water Directive (98/83/EEC)
The table shows that, except Zn at L/S dependency test, metal concentrations exceed the mandatory values for
surface and drinking water. These levels may be found for several of the material disposed in open dumpsites,
while the level are comparable with other findings that investigated metal concentrations is specific open
dumpsite leachates. Therefore, exposure to continuous atmospheric conditions and oxygen penetration may
enhance diffusion of constituents to groundwater. Mor et al. (2006) showed that underground waters close to
dumpsites are subject of leachate percolation posing risk to human health and environment.
5.1.2 Assessment of substrate specific factors influencing metal emission
The materials used for the purpose of this study are very much diverse and their total concentration and
composition is different. Therefore, it is important to investigate the influence of sample matrix and its
chemical composition on the leaching behavior. For example, different metal concentrations play a significant
role in the amount and types of metal leached out from the solid phase and eluate pH for different material.
41
Also metal precipitation as hydroxide and chlorides or other forms, plays a role in metal mobility. PCBs and
shredder fluff are characterized by high level of DOC, which may play a role in metal complexation at alkaline
region. All above factors may influence metal emission to the environment and are explained in more detail
below.
The results show that different materials leach out different metal concentrations under batch leaching
conditions at natural pH. The results show that Cu is the most abundant element from the three materials
followed by Fe, Zn and Pb. The above metals record the highest percentage in PCBs followed by shredder fluff
and Li-ion battery ash. Cu results to leach more at liquid to solid dependency test (L/S 10 l/kg) compared to pH
dependency test (pH 3), whereas for Pb is the other way around.
Musson et al. 2006, showed that Zn and Fe inhibit Pb solubility due to their higher oxidation potential. The
results of this study indicate that total concentrations of Fe and Zn are two times more than Pb concentration,
whereas Cu concentration is recorded almost 10 times higher than Fe and Zn concentrations. That means that,
Pb inhibition by the fast oxidation of Fe and Zn may lead to Cu mobility at natural pH. Also precipitation with
sulfates might be considered as a potential factor. The dissolved sulfate may contribute to form complexes
with copper and lead affecting their mobility.
In general, the mobility of heavy metals is maximized at acidic pH. However, for PCBs Fe and Zn concentrations
are lower at pH 3 compared to natural pH at L/S 10. On the other hand, Pb concentration increases with
decreasing pH. Tack (2010) argued that when pH decreases below 6, metal dissolution increases in the
following order Hg > Pb > Cu > Mn > Ni > Zn > Cd. This indicates that Pb is highly active in acidic conditions
(Figure 25).
Figure 25 Relative share of Fe, Cu, Zn and Pb in PCB, shredder fluff and Li-ion battery ash for the total metal content (aqua regia digestion) and metal release from L/S dependency test (L/S 10 l/kg) and pH dependency test (pH 3)
However, Ni is leaching more for Li-ion battery because its availability is higher compared to Pb. Therefore the
above order may also depend on metal availability.
Spalvins et al. (2008) showed that Pb mobility is pH depended and is expected to be high at acidic phase of the
landfill, where Pb is expected to chelate with volatile fatty acids and gradually decreasing at methanogenesis
phase. El- fadel et al. (1997) showed that leachate pH in a solid waste landfill especially with the presence of
Total content (mg/kg)
Fe
Cu
Zn
Pb
L/S 10 L/kg
Fe
Cu
Zn
Pb
pH 3
Fe
Cu
Zn
Pb
42
industrial waste is in the ranges of 1.5 to over 9.5. As above, Pb concentration is expected to increase in case
of disposing WEEE in the landfill especially during acidic phase of waste stabilization (Spalvins et al. 2008).
pH is an important factor that determine metal leaching behavior. Different pH ranges are recorded for
different eluate materials without adding any additional acid or base. This explains the diversity and
heterogeneity of the materials. Metals from Li-ion battery ash are leached at around pH 10. Results from
shredder fluff are recorded for eluate around pH 8 metal concentrations from PCB < 10 mm are recorded at a
relatively acidic pH range of 4 to 5. This level of pH for PCBs is also found in the literature, where Khandpur
(2006) showed that phenolic laminates make use of phenolic resins, consisting of a high acidity which might be
the reason of decreasing pH.
Precipitation in solid compound formation including oxides, hydroxides, carbonates, phosphates, silicates and
some cases sulfates (Tack, 2010). Results show that Cu precipitates as Cu(OH)2 from shredder fluff and Li-ion
battery ash. Pb precipitates as Pb(OH)2 from shredder fluff and it is not detected at L/S 10 from Li-ion battery.
Furthermore, for values less or equal to detection limit 0.02 mg/kg, ion activity product results greater than
constant solubility product, which leads to Pb(OH)2 precipitation from Li-ion battery ash. However, it is not
clear if Pb is leached out or retained to the solid phase. Cu is also precipitating as CuCl from Li-ion battery ash,
because of high concentration of Cl-. This may be the reason why Cu concentration in solution is lower
compared to Pb. Therefore, the leached concentrations should take into consideration the amount of metals.
All this discussion contribute to metal precipitation under aerobic conditions. Precipitation with sulfides under
anaerobic conditions needs also to be investigated.
Li-ion battery ash, is characterised by relatively alkaline eluate pH range, which might play a role in buffering
the acidity produced during organic matter degradation and sulphide oxidation in landfill. However, further
studies are needed to investigate the role of organic substances in the mobility of heavy metal, and maybe,
additional experiments are needed by mixing the input material with organic matter. Except the methanogenic
stage, there is very little information on the factors that affect pH change in different landfill layers (Bozkurt et
al. 2000).
On the other hand, although shredder fluff and Li-ion battery ash material show high buffering capacity at L/S
dependency test, in an open dump site, pH buffering capacity will deplete due to infiltration of oxygen,
formation of CO2 and acidic rain infiltration (Bozkurt et al. 2000). As a result, pH will drop leading to metal
mobility and increase metal release. Again precipitation might happen while mobile metals might penetrate
into the lower layers or migrate to soil, underground or surface water affecting food chain and drinking water.
In terms of DOC concentration, the results show that DOC concentration is recorded relatively high for
shredder fluff and PCBs. For shredder fluff it even exceeds the EU waste acceptance criteria at landfills for
hazardous waste of 1000 mg/kg dry weight recording a concentration of 3,467 ± 46 mg/kg. These higher levels,
classify this compound as a key pollutant for PCBs and shredder fluff. PCBs are composed of a variety of acid
resins which contain the carboxylic group in their chemical structure which may form complexes with heavy
metals in alkaline region (Bernier 1988). This is also explained by Yang (1993) who reported that, PCBs
originating from household electronic equipments are mainly composed by a mixture of epoxy and acrylic resin
solder, explaining also why DOC is found in considerable amounts in PCBs and shredder fluff sampling material.
43
To conclude, metal availability and composition is shown to be different for different materials. Substrate
specific chemical factors, such as eluate pH under neutral and simulated conditions, presence of DOC,
hydroxides and chlorides, create specific conditions for metal mobility. All above factors leads to different
processes such as sorption, dissolution, precipitation Simulation of worst case scenarios and exposure of the
material under open atmospheric conditions, may enhance metal dissolution due to oxidation and acidification
processes that may lead to diffusion of constituents to fresh water and seawater.
5.2 Prediction of metal release based on geochemical modeling
L/S dependency and pH dependency leaching test are used for characterization of WEEE as well as for model
prediction. Sloot et al (2006) showed that these tests provide the necessary information for chemical
speciation prediction. However, leaching tests are not enough to predict and take into consideration all
necessary factors that impact metal behavior under specific environmental conditions. Therefore, prediction
model is used to characterize the materials with limited tests and parameters (Sloot et al. 2006).
ORCHESTRA geochemical modeling is used to calculate the prediction equations and the possible dissolution
and sorption reactions. Predictions are performed for metal solubility as function of pH as well as liquid – solid
partitioning of metals taking into consideration the chemical speciation predictions. Sloot et al. (2012) showed
that chemical speciation characteristics are the same for all materials and therefore, mineral formation, co-
precipitation with Fe, Al and Mn oxides, bounding with DOC and particulate organic matter (POM) are
important and may play a role in metal mobility.
As above Figure 26 illustrate an example on how the partitioning of elements between liquid-solid phases may
contribute to metal prediction solubility as function of pH, in comparison with the test results from pH
dependency test. This illustration belongs to Cu and Pb solubility from Li-ion Battery ash.
0.0001
0.001
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Cu+2]
0.0001
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Pb+2]
44
Figure 26 pH depencency prediction and phase distribution modelling results for Cu and Pb in comparison with pH dependency leaching test results from Li-ion Battery ash
As shown in Figure 26, Cu for instance may potentially co-precipitate with iron oxides, can be involved in
mineral formation, may interact with clay and form bounds with POM and DOC. Pb may potentially participate
in sorption with iron oxides, precipitate as lead hydroxide as well as interact with clay, or with POM in the solid
phase and DOC in the liquid phase in alkaline media. As above, the mobility of these elements is affected and
differs from the ones shown in lab scale. Modeling results for a wider range of elements is found in ANNEX 7.
However, in some cases, the model does not predict the leachability of some metals at high pH. Some
elements show decrease in concentration, whereas the prediction shows increase. This may happen because
no mineral is found from the database at high pH, underestimation of the amount of reactive surfaces or not
all binding mechanism are considered by the database (Dijkstra et al. 2004).
Taking into consideration landfill conditions, the majorities of heavy metals are retained by Mn and Fe oxides,
adsorbed by organic matter, precipitate as hydroxides, carbonates, phosphates and silicates and further down
precipitate as sulfides in full anaerobic conditions, enhancing heavy metal immobilization (Sang et al. 2012). On
the other hand, Dijkstra et al. (2006) showed that DOC may form complexes with heavy metals in solution and
may enhance mobility especially in alkaline region. In open dumpsites, precipitation mechanism might be
affected by oxidation through oxygen penetration, which enhances metal dissolution and diffusion (Bozkurt et
al. 2000; Prechthai et al. 2008; Sang et al. 2012).
However, this study is limited to sulfate and carbonate measurements, which might play a role in solubility
predictions. Also, percolation test is needed to perform advanced mass transfer prediction model over a
defined period of time.
5.3 Comparison of environmental quality and landfill acceptance criteria
Directive 2008/105/EC on environment quality standards in the field of water policy set up maximum
allowable concentrations for 33 substances of concern, including the toxic metals such as Cd, Pb and Ni. The
purpose of this directive is to protect the quality of aquatic environment by chemical pollution in short and
long term and to prevent the aquatic life toxicity, accumulation in ecosystems and threat to human health.
1E-06
1E-04
1E-02
1E+00
1E+02
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Cu+2]
Free DOC-bound
POM-bound FeOxide
0.0001
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
[Pb+2]
Free DOC-bound POM-bound
FeOxide Clay Pb[OH]2
45
On the other hand, acceptance criteria for disposing the wastes in a separate and safe way are established by
the landfill directive (EU 1999/31/EC) and Council Decision 2003/33/EC. These criteria take into consideration
(i) the material source of contaminant based on the constituent leachability over time and (ii) environmental
scenarios based on the migration of contaminant from the landfill to groundwater.
The experimental data, show that metal concentrations in the pH dependency test exceed any regulation limits
such as drinking water, surface water as well as the landfill acceptance criteria for all classes. On the other
hand, batch leaching test (L/S 10 l/kg) results do not comply with surface and drinking water standards as well
as acceptance regulatory limits for inert waste landfills. However, they do comply with European acceptance
limits for hazardous to non hazardous waste landfills (Table 9).
Table 9 Comparison of experimental data from pH dependency test (pH 3) and L/S dependency test (L/S 10 l/kg) with landfill acceptance criteria for inert, non hazardous and hazardous waste and threshold limits for surface drinking water
Name Max. Release pH dependency test pH 3 (mg/kg)
Max. Release L/S dependency test pH: 4.5 – 10.5 (mg/kg)
EU regulatory limit(4) L/S 10 L/kg pH: 5.5 -13 (mg/kg)
(1) Li-ion Battery ash, (2) PCB < 10 mm, (3) Shredder fluff (5) Surface Water Directive (77/440/EEC) / 1989 Regulations (4) Range of criteria for waste acceptable at landfills for inert waste (Class 0 and I) and non – hazardous to hazardous waste (Class II, III and IV) (2003/33/EC). (5) Directive 2008/105/EC on environment quality standards in the field of water policy (7) Drinking Water Directive (98/83/EEC)
The above results show that the disposal of the investigated materials in an open dumpsite may pose serious
health and environmental risk, by releasing high quantity of toxic elements under specific environmental
conditions. Metal diffusion to soil surface and groundwater may affect terrestrial and aquatic food chain.
Dumping of waste containing heavy metal directly on the surface of the soil leads to soil contamination and
vegetation as well as mitigation to wider areas (Ali et al. 2014).
5.4 Toxicity assessment of WEEE related metal emission
Following the discussion in section 5.3., concerning the fate of toxic elements disposed in dumpsite it becomes
important to also undertake a toxicity assessment to characterize the human and eco-toxicological impact of
inorganic compounds. The calculations to determine the toxicity levels have been performed with the
environmental model USEToxTM. The results showed in Table 10 indicate that that Cu, Ni and Pb leached out
46
mainly from pH dependency test at acidic pH 3 pose risk to the environment and human health through
emission into fresh and coastal marine waters. Ba, Cd and Co contribute mainly to the ecotoxicity. For Co, the
limits for total human impact are not regulated yet. Therefore, the toxic effect of Co to human health is not
clear.
Table 10 Toxicity characterization factor for inorganic constituents for freshwater and seawater for three materials such as Li-ion Battery ash, shredder fluff and PCB < 10 mm
Name
Scenarios for Scenarios for leachable content
Emission to Fresh water [CTUh = cases.kgemitted
-1] Emission to coastal marine water [CTUh = cases.kgemitted
-1]
Emission to Fresh water [CTUe = PAF.m3.d.kgemitted
-1] Emission to coastal marine water [CTUe = PAF.m3.d.kgemitted
(1) pH 3 – Li – ion battery ash, (2) pH 3 – PCB < 10 mm, (3) pH 3 - Shredder fluff, (4) L/S 10 – PCB < 10 mm, (5) L/S 10 – Shredder fluff Note: From Li-ion battery ash L/S 10 there is not effect.
where: “CTUh/kg - comparative toxic unit that estimates the increase in morbidity in the total human population per unit mass of a chemical emitted (cases/kg)” (Mckone et al. 2010). “CTUe - potentially affected fraction of species (PAF) integrated over time and volume per unit mass of a chemical emitted” (Mckone et al. 2010).
The above results indicate that the level of heavy metal toxicity in a dumpsite leachate is high and might pose
aquatic toxicity, accumulation in ecosystems and food chain and threat to human health. Prechthai et al.
47
(2008) showed that heavy metal toxicity from a site specific dumpsite landfill had the potential to affect the
rice plant growth close to the dumpsite. Also, dumpsite leachate investigation from three open dumpsites in
Malaysia resulted toxic to crap fish posing risk to other animals and human health which are exposed to the
same toxic risk (Alkassasbeh et al. 2009).
48
CHAPTER V
5. CONCLUSIONS and RECOMMENDATIONS
5.1 Conclusions
Within the limitations of this study the following can be concluded.
The leachable metal content from PCBs, Shredder fluff and Li-ion battery ash investigated under selected test
conditions such as pH and liquid–solid ratios show that Cu, Pb, Zn, Fe, Cd, Ni, Co and As are the most abundant
metals in three materials. Pb and Cu have the highest concentrations in PCBs, Cd and Ba in shredder fluff, and
Fe, Ni, Co and As in Li-ion battery ash.
Results show that the leachable metal content is also found to be strongly pH dependent. At pH 3, it is around
10 times lower compared to total metal content, whereas at L/S 10 l/kg is around 5000 - 10,000 times lower.
For particular metals, leaching test results show that Pb is the most leached metal in acidic condition and L/S
10 (l/kg). Its leachability decreased with increasing pH due to presence of Fe and Zn as fast oxidizers. Also, Cu
found in PCBs showed the highest leachability at acidic pH, whereas Cd appeared to be the most leachable
metal in L/S 10 (l/kg).
Total metal concentrations do not comply with class IV of landfill acceptance criteria, which means that the
underground hazardous waste disposal is not an option for the investigated material when considering the
total leachable content. However, the leachable metal content under neutral pH at L/S 10 does comply with
the hazardous waste landfill acceptance criteria. In terms of soil thresholds, the tested materials impose risk
for soil contamination, given the fact that total metal content exceeds even the highest limits of soil threshold
values. Therefore, the disposal of the investigated materials in open dumpsites may lead to surface water
contamination and mitigation to wider areas.
Concerning toxicity assessment of heavy metals, Cu, Ni and Pb concentrations leached out at pH 3 pose risk to
the environment and human health through emission into fresh and coastal marine waters. Ba, Cd and Co
contributes mainly to the ecotoxicity. For Co, the limits for total human impact are not regulated yet.
Therefore, the toxic effect of Co to human health is not clear yet.
49
5.2 Recommendations
Mobility of heavy metals in open dumpsites is time and site specific. Therefore, application of leaching
tests in characterization of constituents from a specific dumpsite leachate would be interesting.
Groundwater samples from different distances from the source may also be investigated in order to
evaluate the migration of pollutant to fresh water.
Measurements of carbonates, sulphates and phosphates are important to understand binding
capacities of the metals as well as in solubility predictions.
This study is limited on metal behavior in aerobic conditions. Therefore is wise to investigate metal
behaviour in anaerobic condition as well as binding with organic matter.
Sorption capacity of soil may be investigated giving the fact that metals complexed with soil particles
are less available in soil solution. Mixing experiments with soil may be investigated further to
understand the sorption capacity of soil particles.
This study is limited in investigation of the physical factors such as advection, percolation and diffusion
that play a role in transport mechanisms of metals. Therefore, percolation test is needed to investigate
the transport of constituents over a defined period of time as well as to perform advanced mass
transfer prediction model over a defined period of time.
Metal concentrations in solution are controlled by sorption – desorption reactions at the surface of the
material containing them. The majority of the studies on sorption – desorption reaction are related
mainly to soil. However, studies sorption – desorption related to specific materials need to be
investigated.
50
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Van der Sloot, H.A. et al., 2006. Developments in the characterisation of waste materials for environmental impact assessment purposes. Journal of Geochemical Exploration, 88(1-3), pp.72–76. Available at: http://linkinghub.elsevier.com/retrieve/pii/S0375674205001044 [Accessed August 15, 2014].
Van der Sloot, H.A. & Dijkstra J.J. 2004. Horizontal standardization and harmonization of leaching test methods for waste, secondary raw materials, construction materials and (contaminated) soil.
Van der Sloot, H.A. et al., 2012. A reference database in LeachXS TM Lite for release of substances from construction products including alternative materials . pp.1–10.
Tack, F. M. G. 2010. Trace elements: general soil chemistry, principles and processes. In: Hooda P (ed) Trace elements in soils, Wiley-Blackwell, In Press. Chapter 2: Trace elements: general soil chemistry, principles and processes.
Townsend, T.G., 2011. Environmental Issues and Management Strategies for Waste Electronic and Electrical Equipment. Journal of the Air & Waste Management Association, 61(6), pp.587–610. Available at: http://www.tandfonline.com/doi/abs/10.3155/1047-3289.61.6.587 [Accessed April 1, 2014].
Tsydenova, O. & Bengtsson, M., 2011. Chemical hazards associated with treatment of waste electrical and electronic equipment. Waste management (New York, N.Y.), 31(1), pp.45–58. Available at: http://www.ncbi.nlm.nih.gov/pubmed/20869229 [Accessed March 25, 2014].
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56
ANNEX 1 Table 1.1 Toxicity characterization factor at pH 3 based on the leachable metal content from pH dependency leaching test (CEN/TS 14429) for Li-ion Battery ash, PCB < 10 mm and Shredder fluff
Name Scenarios for Scenarios for leachable content pH 3
Li-ion Battery ash Emission to Fresh water
[CTUh = cases.kgemitted-1]
Emission to coastal marine water [CTUh = cases.kgemitted
Table 1.2 Toxicity characterization factor at L/S 10 (l/kg) based on the leachable metal content for L/S dependency test (CEN/TS 12457) for Li-ion Battery ash, PCB < 10 mm and Shredder fluff
Name Scenarios for Scenarios for leachable content L/S 10 (L/kg)
Li-ion Battery ash Emission to Fresh water
[CTUh = cases.kgemitted-1]
Emission to coastal marine water [CTUh = cases.kgemitted
ANNEX 2 Primary and secondary sampling procedure for PCBs, Shredder fluff and Li – ion battery ash
Figure 27 Primary sampling procedure for shredder PCBs, Shredder fluff and Li – ion battery ash
Table 11.1 Secondary sampling procedure for preparing the test material for PCBs, Shredder fluff and Li – ion battery ash
Primary samples Procedure Secondary sample for laboratory
test samples
Fluff Sieving 10mm Fluff <10 mm
Low grade PCB
Step 1: Crushing Mewa Unicut (Cutting size 40 mm)
PCB < 40mm
Step 2: Retsch Hammermill (Cutting size 10 mm)
PCB < 40mm
Fine fraction incineration residue
Air drying Sieving at 10 mm to remove coarse scrap fraction
Battery ash
60
ANNEX 3 Table 2, 3, 4 and 5 show the mass distribution calculation for each input material including the net material
weight and the percentage by weight for PCBs, shredder fluff and Li-ion battery ash input material.
Table 3.1 Mass distribution calculation for PCB ˂ 10 mm
Sieve size (mm) Empty pot weight (g)
Pot + material weight (g)
Net Material weight (g)
% by weight
˂ 1 115.60 809.80 694.20 13.27
1 116.20 705.00 588.80 11.26
2 116.30 560.60 444.30 8.50
3.15 124.90 330.60 205.70 3.93
4 116.30 1,997.80 1,881.50 35.98
6.7 116.30 1,166.20 1,049.90 20.08
8 116.00 455.30 339.30 6.49
9.5 115.50 132.60 17.10 0.33
11.2 117.60 126.50 8.90 0.17
Total Amount 5,229.70 100.00
Table 3.2 Mass distribution calculation for Shredder fluff
Sieve size (mm) Empty pot weight
(g) Pot + material
weight (g) Net Material
weight (g) % by weight
˂ 1 115.70 744.00 628.30 47.52
1 115.50 277.30 161.80 12.24
2 116.00 174.30 58.30 4.41
3.15 116.00 133.50 17.50 1.32
4 116.20 158.30 42.10 3.18
6.7 116.20 133.10 16.90 1.28
8 116.00 138.50 22.50 1.70
11.2 116.00 124.50 8.50 0.64
16 116.20 482.40 366.20 27.70
Total Amount 1,322.10 100.00
Table 3.3 Mass distribution calculation for Li – ion battery ash
Sieve size (mm) Empty pot weight
(g) Pot + material
weight (g) Net Material
weight (g) % by weight
˂ 1 185.40 4,928.00 4,742.60 57.12
1 115.50 1,780.00 1,664.50 20.05
2 116.20 822.60 706.40 8.51
3.15 115.20 273.90 158.70 1.91
4 185.40 441.10 255.70 3.08
6.7 185.10 614.80 429.70 5.18
8 185.34 368.50 183.16 2.21
9.5 185.45 347.60 162.15 1.95
Total Amount 8,302.91 100.00
61
ANNEX 4 This annex includes the test portion calculation for each experiment such as pH dependency test (CEN/TS 14429) and L/S dependency test (CEN/TS 12457 1-4) and for each input matrices.
1. pH controlled leaching test (CEN/TS 14429)
Table 4.1 Test portion calculations for shredder fluff pH dependency test (CEN/TS – 14429)
Material SHREDDER
FLUFF
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L
(ml)
pH 3 57.400 55.1 96.0 4.2 548.7
pH 4.5 59.810 57.42 96.0 4.2 571.8
pH 6 60.250 57.84 96.0 4.2 576.0
pH 7.5 59.700 57.312 96.0 4.2 570.7
pH 9 60.010 57.6 96.0 4.2 573.6
pH 10.5 60.110 57.7 96.0 4.2 574.6
pH 12 60.109 57.7 96.0 4.2 574.6
BLANK pH 12 600
Table 4.2 Test portion calculations for PCB ˂ 10 mm pH dependency test (CEN/TS – 14429)
Material PCB
(˂ 10 mm)
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L
(ml)
pH 3 60.063 59 98.2 1.8 588.9
pH 4.5 60.229 59.17 98.2 1.8 590.6
pH 6 60.025 58.87 98.1 2.0 587.5
pH 7.5 60.089 59.74 99.4 0.6 597.1
pH 9 60.074 59.54 99.1 0.9 594.9
pH 10.5 60.095 58.77 97.8 2.3 586.4
pH 12 60.0191 59.45 99.1 1.0 593.9
BLANK pH 3 600
62
Table 4.3 Test portion calculations for Li – ion battery ash pH dependency test (CEN/TS – 14429)
Material BATTERY
Li - Fe
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L (ml)
pH 3 60.156 59.55 99.0 1.0 594.9
pH 4.5 60.080 59.48 99.0 1.0 594.2
pH 6 60.025 59.42 99.0 1.0 593.6
pH 7.5 59.940 59.34 99.0 1.0 592.8
pH 9 59.970 59.37 99.0 1.0 593.1
pH 10.5 60.107 59.5 99.0 1.0 594.4
pH 12 60.275 59.67 99.0 1.0 596.1
where
DR (%) = 100 * Md/Mw
MC (%) = 100 (Mw – Md)/Md
L (ml) = (10 – MC/100) * Md
2. L/S dependency test (CEN/TS 12457 1-4)
Table 4.4 Test portion calculation for PCB < 10 mm L/S dependency test (CEN/TS 12457 1-4)
Mass required (g)
PCB < 10 mm
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L (ml)
8
7.890 7.81 99.0 1.0 78.0
8.085 8.004 99.0 1.0 80.0
8.051 7.97 99.0 1.0 79.6
16
16.480 16.32 99.0 1.0 81.4
15.910 15.75 99.0 1.0 78.6
16.070 15.9 98.9 1.1 79.3
40
39.960 39.56 99.0 1.0 78.7
39.840 39.44 99.0 1.0 78.5
39.490 39.095 99.0 1.0 77.8
80
80.730 79.92 99.0 1.0 79.1
80.830 80.03 99.0 1.0 79.2
79.870 79.07 99.0 1.0 78.3
160
159.84 158.25 99.0 1.0 77.5
159.34 157.75 99.0 1.0 77.3
159.01 157.42 99.0 1.0 77.1
63
Table 4.5 Test portion calculation for shredder fluff L/S dependency test (CEN/TS 12457 1-4)
Mass required (g)
shredder fluff
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L (ml)
8 8.060 7.74 96.0 4.1 77.1
16 15.930 15.3 96.0 4.1 75.9
40 39.820 38.23 96.0 4.2 74.9
80 80.050 76.85 96.0 4.2 73.7
160 157.89 152 96.3 3.9 70.1
NOTE: this is one run experiment with triplicate measurements
Table 4.6 Test portion calculation for Li – ion battery ash L/S dependency test (CEN/TS 12457 1-4)
Mass required (g)
Li-ion battery ash
Mass before drying Mw (g)
Mass after
drying Md (g)
Dry Residue DR (%)
Moisture Content MC (%)
Leachant Volume L (ml)
8
8.113 8.032 99.0 12.6 80.2
8.138 8.057 99.0 12.5 79.6
8.130 8.046 99.0 12.6 79.4
16
16.086 15.93 99.0 6.3 79.5
16.086 15.93 99.0 6.3 79.5
15.990 15.83 99.0 6.4 79.0
40
40.020 39.62 99.0 2.5 78.8
40.170 39.77 99.0 2.5 79.1
40.200 39.79 99.0 2.5 79.2
80
80.350 79.55 99.0 1.3 78.8
80.360 79.56 99.0 1.3 78.8
80.120 79.32 99.0 1.3 78.5
160
159.59 157.99 99.0 0.6 77.4
159.75 158.15 99.0 0.6 77.5
159.69 158.1 99.0 0.6 77.5
where
DR (%) = 100 * Md/Mw
MC (%) = 100 (Mw – Md)/Md
L (ml) = (X – MC/100) * Md, where X presents L/S ratio 10; 5; 2; 1; 0.5 for 8 g; 16 g; 40 g; 80 g and 160 g
respectively.
64
ANNEX 5 Table 5.1 pH dependency test results (CEN/TS 14429) for the leachable metal content in mg/kg at L/S 10 (l/kg) (n=3)
Note: for shredder fluff there are no measurements for L/S 0.5 l/kg. Leachate is absorbed from the material. u.d. – under detection limit (0.02mg/kg)
66
0.01
0.1
1
10
100
1000
10000
Na Mg Al K Ca Cr Mn Fe Co Ni Cu Zn Cd Ba Pb Cl-
Me
tal r
ele
ase
(m
g/kg
)
L/S 10 l/kg at natural pH
PCB < 10 mm (pH 4-5)
Shredder fluff(pH 8)
Li-ion Battery ash(pH 10)
0.01
0.1
1
10
100
1000
10000
100000
Na Mg Al K Ca Cr Mn Fe Co Ni Cu Zn Cd Ba Pb Cl- As
Re
leas
e (
mg/
kg)
pH 3 at L/S 10 l/kg
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
67
Figure 28 The leachable metal content from L/S dependency test at L/S 10 L/kg and pH dependency test at pH 3, from PCB < 10 mm, shredder fluff and Li-ion battery ash
Note: Detection limit < 0.002 mg/L, except Ca with DL < 1 mg/L
Values for K and Cr are missing at Total Metal Concentration
1
10
100
1000
10000
100000
1000000
Na Mg Al Ca Mn Fe Co Ni Cu Zn Cd Ba Pb As
Tota
l me
tal c
on
ten
t (m
g/kg
)
Aqua regia digestion
PCB < 10 mm
Shredder fluff
Li-ion Battery ash
68
ANNEX 6
Table 6.1 Metal precipitation for specific constituents within specific conditions such as pH, contact time and L/S ratio for PCBs, shredder fluff and Li-ion battery ash. Ion activity product is calculated based on hydroxide ion calculation and chloride measurements by titration.
Experiment Compound Formula Ksp* (250C) Calculated IAP** Precipitation (YES/NO)
pH dependency shredder fluff a. pH: 3.47 b. pH: 4.2 c. pH: 6.35 d. pH: 7.51 e. pH: 9.58 f. pH: 11.19 g. pH: 12.26
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 10.6 x 10-34
g. 8.4 x 10-8 YES YES
Copper hydroxide
Cu(OH)2 4.8 x 10-20 c. 1.5 x 10-21 d. 7.9 x 10-19 g. 5.2 x 10-6
NO YES YES
Iron hydroxide Fe(OH)2 4.87 x 10-17 d. 1.8 x 10-19 e. 2 x 10-10 g. 6.4 x 10-5
NO YES YES
Lead hydroxide Pb(OH)2 1.43 x 10-20 d. 3.8 x 10-20 g. 3.9 x 10-6
YES YES
Magnesium hydroxide
Mg(OH)2 5.61 x 10-12 e. 1.4 x 10-12 f. 7.8 x 10-6 g. 2.5 x 10-4
NO YES YES
Manganese hydroxide
Mn(OH)2 2 x 10-13 d. 4.1 x 10-16 g. 1.6 x 10-2 e. and f. are under the detection limit
NO YES
Nickel hydroxide Ni(OH)2 5.48 x 10-16 d. 6.2 x 10-15 e. f. and g. are under detection limit
YES
Zinc hydroxide Zn(OH)2 3 x 10-13 e. 3.5 x 10-11 g. 3.4 x 10-6
YES YES
pH dependency PCB < 10 mm a. pH: 3.8 b. pH: 5.52 c. pH: 6.2 d. pH: 7.16 e. pH: 8.9 f. pH: 10.2 g. pH: 11.35
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 1.8 x 10-35 b. 5.3 x 10-32
g. 3.1 x 10-10
NO YES YES
Copper hydroxide
Cu(OH)2 4.8 x 10-20 c. 5.5 x 10-24 d. 1 x 10-22 e. 1.7 x 10-19
g. 1.5 x 10-13
NO NO YES YES
Iron hydroxide Fe(OH)2 4.87 x 10-17 f. 4.4 x 10-14
g. 6 x 10-8 a. and b. do not precipitate
YES YES
69
c. d. and e. are under detection limit
Lead hydroxide Pb(OH)2 1.43 x 10-20 c. 4.8 x 10-22 g. 3.4 x 10-7 d. and e. are under the detection limit
NO YES
Magnesium hydroxide
Mg(OH)2 5.61 x 10-12 e. 5.5 x 10-17 f. 4.5 x 10-9 g. 6.5 x 10-7
NO YES YES
Manganese hydroxide
Mn(OH)2 2 x 10-13 d. 3.3 x 10-18 f. 1.6 x 10-14
g. 3 x 10-12 e. is under the detection limit
NO NO YES
Nickel hydroxide Ni(OH)2 5.48 x 10-16 c. 1.9 x 10-22
f. 1.9 x 10-14 d. e. and g. are under detection limit
NO YES
Zinc hydroxide Zn(OH)2 3 x 10-13 d. 1.2 x 10-15 f. 2.1 x 10-9
g. 3.4 x 10-7 e. is under the detection limit
NO YES
pH dependency Li-ion Battery ash a. pH: 3.75 b. pH: 4.44 c. pH: 6.14 d. pH: 7.57 e. pH: 8.4 f. pH: 10.35 g. pH: 12.56
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 4.2 x 10-31
g. 6.2 x 10-7 YES YES
Copper hydroxide
Cu(OH)2 4.8 x 10-20 b. 3.2 x 10-23
c. 2.7 x 10-21 d. 3.2 x 10-19
g. 3.2 x 10-8
NO NO YES YES
Iron hydroxide Fe(OH)2 4.87 x 10-17 d. 1.2 x 10-19 e. 3.8 x 10-18 f. 3.3 x 10-14
g. 1.3 x 10-9
NO NO YES YES
Lead hydroxide Pb(OH)2 1.43 x 10-20 b. 1.1 x 10-21 g. 5 x 10-9 c. d. e. and f. are under detection limit
NO YES
Magnesium Mg(OH)2 5.61 x 10-12 e. 6.7 x 10-15 NO
70
hydroxide f. 7.2 x 10-13 g. 2 x 10-9
NO YES
Manganese hydroxide
Mn(OH)2 2 x 10-13 e. 5.2 x 10-14 f. and g. are under the detection limit
NO
Zinc hydroxide Zn(OH)2 3 x 10-13 e. 1.5 x 10-17 f. 4.2 x 10-11
g. 7.5 x 10-8
NO YES YES
Copper chloride CuCl 1.7 x 10-7 a. 5 x 10-6 b. 3.6 x 10-6 c. 1.2 x 10-7 d. 1.1 x 10-8
e. 4.3 x 10-9
f. 2.4 x 10-7
YES YES NO NO NO YES
LS dependency PCB < 10 mm a. L/S 10 (L/kg) b. L/S 5 (L/kg) c. L/S 2 (L/kg) d. L/S 1 (L/kg) e. L/S 0.5 (L/kg). Chloride measurements for L/S 0.5 are not available
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 7.3 x 10-32
b. 6.3 x 10-31
c. 9.8 x 10-33
d. 1.2 x 10-32
e. 1.1 x 10-32
YES YES YES YES YES
LS dependency Shredder fluff a. L/S 10 (L/kg) b. L/S 5 (L/kg) c. L/S 2 (L/kg) d. L/S 1 (L/kg) e. L/S 0.5 (L/kg). Chloride and hydroxide measurements for L/S 0.5 are not available.
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 6.5 x 10-22
b. 7.1 x 10-23
c. 1.6 x 10-23
d. 8.8 x 10-23
YES YES YES YES
Copper hydroxide
Cu(OH)2 4.8 x 10-20 a. 2.6 x 10-17
b. 1.2 x 10-18 c. 7.9 x 10-19
d. 1.5 x 10-17
YES YES YES YES
Lead hydroxide Pb(OH)2 1.43 x 10-20 a. 1.5 x 10-18 b. 2 x 10-19 c. 1.3 x 10-19 d. 4.1 x 10-18
YES YES YES YES
Copper chloride CuCl 1.7 x 10-7 a. 7.2 x 10-9 b. 1.1 x 10-8 c. 7 x 10-8 d. 1 x 10-6
NO NO NO YES
LS dependency Li–ion battery ash
Aluminum hydroxide
Al(OH)3 3 x 10-34 a. 1.1 x 10-15
b. 1 x 10-14
c. 1.4 x 10-14
YES YES YES
71
a. L/S 10 (L/kg) b. L/S 5 (L/kg) c. L/S 2 (L/kg) d. L/S 1 (L/kg) e. L/S 0.5 (L/kg).
d. 3.4 x 10-15 e. 2.9 x 10-16
YES YES
Cobalt hydroxide
Co(OH)2 5.92 x 10-15 Under detection limit Ksp = 10-12
MAYBE
Copper hydroxide
Cu(OH)2 4.8 x 10-20 a. 1.1 x 10-14
b. 1.1 x 10-13 c. 9.3 x 10-14
d. 1.7 x 10-13 e. 2.8 x 10-14
YES YES YES YES YES
Iron hydroxide Fe(OH)2 4.87 x 10-17 b. 7 x 10-15 c. 4.4 x 10-14 d. 4.8 x 10-14 e. 8.5 x 10-15 a. is under the detection limit
YES YES YES YES
Lead hydroxide Pb(OH)2 1.43 x 10-20 Under the detection limit Ksp = 10-16
MAYBE
Nickel hydroxide Ni(OH)2 5.48 x 10-16 Under detection limit Ksp = 10-12
MAYBE
Zinc hydroxide Zn(OH)2 3 x 10-13 a. 1.8 x 10-14 b. 1.2 x 10-13
c. 1.2 x 10-13
d. 3.4 x 1013
e. 5.4 x 10-14
NO NO NO YES NO
Copper chloride CuCl 1.7 x 10-7 a. 8.5 x 10-6 b. 4.6 x 10-5 c. 5.7 x 10-5 d. 4 x 10-4 e. 4 x 10-4
YES YES YES YES YES
* Ksp – Constant solubility product
**IAP – Ion activity product
72
ANNEX 7 PCB < 10 mm
0.0001
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Cu+2
Free DOC-bound
FeOxide Tenorite
0.0001
0.001
0.01
0.1
1
10
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Ni+2
Free DOC-bound
POM-bound FeOxide
Clay Ni[OH]2[s]
0.0001
0.001
0.01
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Pb+2
Free DOC-bound
FeOxide Pb[OH]2
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Zn+2
Free DOC-bound POM-bound
FeOxide Clay Zincite
73
Shredder fluff
1E-06
1E-05
1E-04
1E-03
1E-02
1E-01
1E+00
1E+01
1E+02
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Cu+2
Free DOC-bound CuprousFerrite
0.0001
0.001
0.01
0.1
1
10
100
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Ni+2
Free DOC-bound
POM-bound FeOxide
0.0001
0.001
0.01
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Pb+2
Free DOC-bound
FeOxide Pb[OH]2
0.1
1
10
100
1000
1 3 5 7 9 11 13
Conce
ntr
ation (
mg/L
)
pH
Phase distribution of Zn+2
Free DOC-bound POM-bound
FeOxide Clay Zincite
74
Li-ion Battery ash
Figure 29 Phase distribution modelling results for toxic metals from PCB < 10 mm, Shredder fluff and Li-ion Battery ash
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