BIOFILTRATION OF MEK AND TOLUENE: PILOT STUDY FOR
CANADIAN GENERAL-TOWER LIMITED'S DRY LAMXNATOR
A Thes i s
Presented to
The Faculty of Graduate Studies
of
The University of Guelph
KENNETH W. ELSIE
In partial fulfilment of requirements
for the degree of
Master of Science
January, 1999
National Library Bibliothèque nationale du Canada
Acquisitions and Acquisitions et Bibliographic Services services bibliographiques
395 Wellington Street 395, rue Wellington Ottawa ON K1A O N 4 Ottawa ON K I A ON4 Canada Canada
YOM nie Voire refarBllcB
Our iVe Notre rëf.rence
The author has granted a non- L'auteur a accordé une licence non exclusive licence dowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or electronic formats. la forme de microfiche/film, de
reproduction sur papier ou sur format électronique.
The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts Grom it Ni la thèse ni des extraits substantiels may be printed or otheNvise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation.
ABSTRACT
BfOFILTRATION OF MEK AND T0LUEHE:PILOT STUDY FOR
CANADIAN GENERAL-TOWER LIMITED'S DRY LAMINATOR
Kenneth W. Elsie University of Guelph, 1999
Advisor: Dr. Lambert Otten
The purpose of this research was to d e t e d n e the feasibility
of using a compost-based biofilter to treat the Canadian
General-Tower ' s dry laminator was te gas s tream containing
methyl ethyl ketone (MEK) and toluene. A pilot-scale
biofilter was connected to the dry laminator exhaust stack
and operated for 156 days. Experiments w e r e conducted to detemine: fate of the contaminants; effect of flow rates;
effect of nutrient supplementation, and; effect of periods of
non-use on the performance of the biofilter. The average
inlet concentration for MEK and toluene w e r e 193 ppmv and 161
pprnv, respectively. The average removal rates for MEK and
toluene were 73% and 49%, respectively. Removal efficiency
was not influenced when f low rates were varied from 2.5 to
9.8 m3/h. Nutrient supplementation did not affect removal
rates. Periods of no chexnical loading of up to two days did
not appear to affect removal rates.
ACKNOWLEDGMENTS
1 would l i k e t o thank Canadian General-Tower Limited f o r
funding this research.
1 wish t o thank m y supervisor, D r . Lambert Otten f o r h i s
support and encouragement and Professor Peter Chisholm f o r
h i s assistance during t h i s research e f fo r t .
1 w i s h t o thank t h e School of ~ n g i n e e r i n g technical
staff Klaus Vogel and Bill Verspagen for their advice and
assis tance i n construct ing the experimental equipment and
Joanne Ryks f o r help i n the laboratory.
1 would l i k e t o thank my wife, D r . Kathyrn G i l e s f o r h e r
support and understanding during this process and her
confidence i n my a b i l i t i e s .
Finally I would l i k e t o give a spec ia l thanks to m y
three children Erik, Graham and Russell f o r providing m e with
t h e inspi ra t ion t o be curious and joyful about l i f e .
T a b l e of Contents
1.0 Introduction ......................................... 1 ................................ 1 . 1 Objectives 4 1 . 2 Experimental Plan .......................... 4
2 .0 Literature Review .................................... 5
...................... 2 . 1 Biofiltration Fundamentals 4
.................. 2 . 2 Biofilter Design and Operation 6 2 . 2 . 1 B a s Design. ......................... 7 2 . 2 . 2 Design P a r m e t e r s . . ...................... 9 2 . 2 . 3 Filter Bed Media ......................... 9 ........................... 2 . 2 . 4 Microorganisms 10 2 . 2 . 5 N t e n t s ............................... 15 ............................ 2 . 2 . 6 Filter B e d pH 16 2 . 2 . 7 Moisture Control ......................... 17 2 . 2 . 8 Elhination Rates and Flow Rates ......... 17
2 . 3 Treatability of Methyl Ethyl Ketone and Toluene . 18 2 . 3 . 1 Chemical and Physical Properties of
Methyl Ethyl Ketone and Toluene .......... 18 2 . 3 . 2 Methyl Ethyl Ketone and Toluene
Biodegradation and ~iofiitration Studies . 19 2 . 3 . 3 Canadian General Tower Stack Data ........ 24
................................ 3 . 0 Materials and Methods 27
.......................... 3 . 1 Experimental Apparatus 27 ......................... 3 . 1 . 1 Biofilter Syst em 27 3 . 1 . 2 Relative Humidity and Temperature
Measurement .............................. 29 3 . 1 . 3 Headloss Measurement ..................... 29
3 - 2 B o t e r M d ................................ 30 3 . 2 . 1 source^.^......,.,.............,....-... 30 ........................ 3 . 2 . 2 Media Preparation 30
3 .3 Analytical Methods .............................. 30 ............................. 3 . 3 . 1 Gas Sampling 30 3 . 3 . 2 Carbon Dioxide ~nalysis .................. 32 3 . 3 . 3 Media Analysis ........................... 34
3 . 3 . 3 . 1 Moisture Content and pH ........... 34 3 . 3 . 3 . 2 Nutrients ......................... 34 3 . 3 . 3 . 3 Microbial Profile ................. 35 3 . 3 . 3 . 4 Accessing the ~ i o f i l t e r Media ..... 35
3.4 Insect Identification ........................... 36 ................................ 3.5 Chemical ~oading 36
............................... 4.0 Results and Discussion 40
4.1 O Rates .................................. 40
4.2 Temperature and Relative Humidity ................................ of the Waste Gas 40
4.3 Moisture Content and pH of the Biofilter Media .. 41 ....................... 4.4 Headloss of the Biofilter 42
4.5 Methyl Ethyl Ketone and Toluene Removal ......... 43 ................. 4.6 E f f e c t of Flow Rates on Removal 48
4.7 Removal of Methyl Ethyl Ketone and Toluene Through the Sections of the Bed.. ............... 49
4.8 Effects of Periods of Non-use and Stagnation on Performance .................................. 50 4.8.1 "No Chemical Loading" Condition .......... 50 ..................... 4.8.2 "Stagnant" Condition 52
......................... 4.9 Carbon Dioxide Analysis 52
........................ 4.11 Nutrient Supplementation 56
............................... 4.12 Microbial Profile 60
.................................. 4.13 Insect Profile 62
...... 5.0 Sources of Experimental Errer.................. 63
6.0 Conclusions .......................................... 64
7.0 Recoendations ...................................... 66 7.0 References .......................................... 67 Appendix A: Gas Chromatograph Calibration Curve
Data ....................................... 70
Appendix B: Sampling Day Calibration Data .............. 76
iii
Appendix C: Sample Calculation for Removal Efficiency and Elimination Capacity
Typical Waste Gas Stream Data: Biofilter MEK and Toluene Inlet and Out l e t Concentration Levels- 83
Appendix D: T-test on the Mean Removal E f f i c i e n c i e s for MEK and Toluene Before and After the Il-day Shut-down..,.......oo..o.~~o.~~~ 87
List of Tables
Table 2-1
Table 2 -2
Table 2 - 3
Table 2 - 4
Table 3.1
Table 3 -2
Table 3.3
Table 4.1
Table 4.2
Table 4.3
Table 4.4
Table 4.5
Table 4.6
Table 4 .7
Table 4 - 8
Table 4.9
Table 4.10
Table 4.11
Design parameters for biofilters.
Total bacteria counts from a full- scale biofilter-
MEK and toluene chemical and physical properties . Typical dry laminator stack and mission data.
GC-FID settings,
Components of certified gas standards.
Summary of production chemicaï loading.
Airflow rates during the study-
Temperature of the inlet and outlet gas stream.
Relative humidity of the inlet and outlet gas stream.
Moisture content and pH of the biofilter media-
Operational conditions and MEK removal.
Operational conditions and toluene removal
Average removal of MEK and toluene under diffesent flow rates-
Percentage of MEK removed by each section.
Percentage of toluene removed by each section.
Frequency of operating full days under the "No Chemical Loading" condition.
Removal rates for MEK and toluene on difiesent days of the same week-
T a b l e 4-12
Table 4 13
T a b l e 4 - 14
Table 4 - 15
Mass balance for MEK i n gram% 56
Mass balance for toluene i n grams. 56
Nutrient levels i n filter media in the 60 original compost and at the end of the study.
Aerobic colony forming units in the 62 filer media .
List of Figures
Figure 1.1
Figure 2.1
F igure 2.2
F igure 3.1
Figure 3 - 2
Figure 4- 1
Figure 4.2
Figure 4 - 3
Figure 4.4
F igure 4.5
Schemcatic of dry laminator process
P o r e space schematic . Schematic of an open single-bed b i o f i l t e r -
Schematic of experimental biofilter system.
Production chemical loading during the study.
Percentage removal of MEK-
Percentage rernoval of toluene.
Carbon dioxide levels of day 58.
Day 5 8 : MEK and to luene i n l e t concen t ra t ion
Day 58: MEK and to luene o u t l e t concen t ra t ion-
vii
1.0 Introduction
Canadian General-Tower Limited (CGT) is Canada ' s largest
manufacturer of polyvinyl chloride (PVC) sheeting. The main
manufacturing facility and head office are located in
Cambridge, Ontario. The prirnary air contaminants emitted by
the facility are methyl ethyl ketone (MEK) and toluene. The
majority of MEK and toluene emissions emanating from the
facility originate from several printers and a dry lamination
process . Previous air emission assessments conducted by CGT have indicated that there is a potential for toluene
concentrations to exceed the Ontario Ministry of Environment
and Energy's provincial guidelines for ambient air quality. Mitigation of the dry laminator waste gas was considered a
priority as it is responsible for about 50% of the total
toluene emissions and about 15% of the total MEK emissions.
The dry laminator department produces door panels for
the automotive industry. The panels are produced by dry
laminating PVC sheeting to polypropylene foam. Figure 1.1
shows a schematic of this process. The solvent in the
adhesive in the dry laminator contains MEK and toluene. The
waste gases contain low concentrations of MEK and toluene
which are exhausted through four stacks located on the roof
of the plant.
There are a host of air pollution control (APC)
technologies which could be used to treat the dry laminator
waste gas including carbon absorption and themal oxidation . However, these are characterized by high capital and
operating costs. Biofiltration, a relatively recent APC
technology, has proven to be an effective and inexpensive
technology for treating waste gas streams containing low
concentrations of biodegradable volatile organic compounds
( W C ) or inorganic contaminants (Groenestijn and Hesselink,
1993; Leson and Winer, 1991). Methyl ethyl ketone and
toluene are both known to be biodegradable and have been
successfully treated in controlled laboratory biofiltration studies (Deshusses et al., 1995; Ottengraf and Van Den Oever,
1983) . However , no literature was found on using
biofiltration to treat a waste gas containing a mixture of MEK and toluene. These factors resulted in CGT commissioning
a study to determine the effectiveness of using biofiltration
to treat the dry laminator gas.
Polypropylene f oam roll O Dry Laminator 7
Stack 6 Emissions - 7 7 Stack 7 Emissions 4-
Stack 8 Emissions --tu Stack 9 Emissions i n
Laminated Polypropylene and PVC 0
Adhesive Coatinq
Infra Red Preheat
Hot Air Oven
Heater
Figure Schematic l amina tor process.
Two options were considered to determine the
effectiveness of using biofiltration to treat the dry
laminator waste gas: a controlled laboratory study and an on-
site pilot study. The main advantage of the controlled
laboratory study is that the operating conditions of the
biofilter can be more precisely controlled, However , the "reall' conditions under which a full-scale biofilter would
have to operate would be very difficult to simulate in the
laboratory. These " real" operating conditions would
include :
i) Continual variation in the concentrations of MEK and
toluene during operation of the dry laminator due to
variations in the product being run, speed of the dry laminator, temperature of the dry laminator and type of glue being used.
ii) Random periods of lower concentrations of MEK and
toluene in the waste gas Stream during production, due
to product change over, or mechanical breakdowns and
jamming of the machine.
iii) Periods of no chemical loading to the biofilter
when the dry laminator is non-operational. The dry
laminator typically operates from 4 to 16 hours per day
from Monday to Friday and is non-operational on weekends. The dry laminator is also non-operational for
periods exceeding 24 hours for maintenance, lack of
production and holiday shut-doms.
Since the primary object of the study is to determine the
effectiveness of treating the dry laminator waste gas, it was decided that the best way to do this would be with an on-site
study using a pilot-scale biofilter.
1.1 O b j e c t i v e s
The prima- objectives of this study wexe to:
i) determine the feasibility of using a compost-based
biofilter to treat the dry laminator waste gas Stream;
ii) demonstrate that the biofilter removed MEK and
toluene through biological oxidation rather than
chemical or physical means.
The secondary objectives of this study were to:
i) detemine the effect of air flow rate on removal efficiency;
ii) determine the effect of nutrient supplementation on removal efficiency through addition of nitrogen to the
biofilter media; and,
iii) determine the effects of periods of non-use on the
biofilter performance.
1.2 Experimental P l a n
The experimental plan involved passing a sample of w a s t e
gas from one of the dry larninator's exhaust hood stacks
through a pilot-scale biofilter system. The biofilter was
operated continuously throughout the duration of the study
(156 days) while a series of experiments were conducted to achieve the study objectives.
2 . 0 L i t e r a t u r e Review
2.1 Biofiltration Fundamentals
In biofiltration the waste gas to be treated is forced through a bed packed with biologically active materials . The packed bed contains an aqueous phase or biofilm, which
contains a diverse ecosystem of rnicroorganisms.
Biodegradable volatile contaminants are absorbed by the bed
material and the biofilm, and subsequently are oxidized by
the microorganisms into less harmful substances.
Basically, a three step process occurs within t h e bed of
the biofilter . Figure 2.1 illustrates the processes
occurring in and around the biofilm and shows characteristic
concentration profiles for the contaminant (VOC) and oxygen.
First, the VOC in the gas phase crosses the interface between
the gas flowing in the pore space and the aqueous biofilm
surrounding the bed material. The VOC then diffuses through
the biofilm to the population of acclimated microorganisms.
The microorganisms obtain energy by oxidizing the VOC as a
primary substrate, or they CO-metabolize the VOC through nonspecific enzymes. Concurrently, there is diffusion and
uptake of nutrients ana oxygen w i t h i n the biofilm. T h e
nutrients are typically supplied by the bed material.
Continuous microbial uptake maintains concentration gradients
driving the diffusive transport in t h e biofilm. A properly
designed and operated biofilter converts target waste gas chernicals into carbon dioxide, water, mineral salts,
increased biomass and other compounds.
VOC Conc-
Oxyqen Conc
Carbon Dioxide
VOC & Oxyqen
Bulk Gas Flow Bed
Gas/Liquid Interface Materiai
Figure 2.1: Pore space schematic.
2 . 2 Biofilter Design and Operation
Biofiltration involves both biodegradation of the
contaminant and transport of the contaminant from the waste
gas to the biofilm. To be successful a biofilter must be
designed and operated to provide:
i ) A suitable environment for the microorganisms :
temperature, moisture, nutrients, oxygen supply and p H must be maintained within acceptable ranges,
ii) Adequate and intimate contact between the gas phase
and the biofilrn surface.
The contaminant's chemical and physical properties such as
water solubility and Henry's Law constants determine its
availability in the biofilm. Poorly soluble compounds with
Henry coefficients higher than 10 (dimensionless) are
considered unfit for treatment in biofilters because of the
l m interfacial mass trans f er rate (Groenesti j n and
Hesselink, 1993).
2.2.1 B a s i c Design
Figure 2.2 illustrates the basic components of a
biofiltration system. The biofilter consists of f ive
components:
i) Pretreatment Components: The waste gas typically has
to be pretreated to ensure a satisfactory environment
for the microorganisms. If the waste gas is high in particulates, a filter may be necessary to protect
downstrearn units from clogging. The waste gas may need to b heated or cooled to the optimal range for
microbial activity. Finally, the waste gas should be
fully saturated with moisture to reduce stripping of
water from the bed. Drying out of the bed will result
in death of most microorganisms and a loss of control
ef ficiency .
ii) Blower and Ducting: A blower is generally required
to overcome the back pressure caused by the pretreatment
components and the filter.
iii) Air Distribution System: The air distribution
system should uniformly feed the waste gas to the
biof ilter bed. The air distribution system often
serves the dual purpose of collecting leachate thac may
drairi from the biofilter bed. Drainage may result from
condensation or over-watering of the biofilter bed.
Collected leachate may be recycled to the humidifier to
reduce liquid waste generation.
iv) Biofilter Bed: The biofilter beds are usually made
£rom compost or peat, which contain the microorganisms
and nutrients. Bulking agents such as wood chips, bark
and inert materials are frequently added as support materials and to prevent high pressure drops in the bed.
v) Irrigation System: Automatic irrigation systems
above, or in the filter bed are frequently used to
maintain the required moisture content in the bed. These systems also allow nutrient solutions or bufiering
solutions to be added as needed-
Clean Gas
Waste
Blower
Gas
B e d
~ r r i g a t i o n System
Air Distribution System I
L ---.---.-*---
Humidifier Drainaqe
Figure 2.2: Schematic of an open single-bed biofilter
2 - 2 . 2 Design Parameters
Some recommended design parameters are summarized in
T a b l e 2.1.
2-2.3 Filter Bed Media
Many of the design parameters for biofilters are related
to the filter bed media- Desirable media properties include
(Swanson and Loehr, 1997):
i ) Optimal microbial environment in which nutrients , moisture, pH and carbon are not limiting factors.
ii) Large specific surface area to maximize the gas-
liquid interface and sorption capacity.
iii) Structural integrity to minimize media compaction
that increases pressure drops and lowers gas retention
times.
iv) High moisture retention to prevent drying of the
filter bed.
v) High porosity to reduce pressure drops across the bed
and ensure an even distribution of incoming gases.
vi) Low bulk density to reduce media compaction
potential.
A wide range of materials have been used in biofilters, with no single material proving ideal. E a r l y biofilters used
soils as the media, but they tended to have high pressure
drops across the bed. Presently, the most widely used media
are compost, peat, bark mulch and mixtures of these (Swanson
and Loehr, 1997). The primary drawback of these media is the
mineralization of the organics comprising the bed. This
"aging" of the bed and compaction leads to bed replacement
every 2 to 5 years (Leson and Winer, 1991). Compost-based
filters typically have higher microbial populations densities
than soil- and peat-based filters (Leson and Winer, 1991).
A variety of materials have been added to beds to
improve performance. Bulking agents such as wood chips,
bark, perlite, vemiculite, or polystyrene spheres can be
added to reduce compaction, increase porosity, achieve more
uniform gas flow, reduce cracking and channeling, and lower
pressure drop (Swanson and Loehr, 1997). Buffering agents
such as limestone, crushed oyster shells and rnarl have also
been added to control bed pH. Granulated activated carbon
(GAC) has also been added to beds as a buffer to improve
performance under shock and fluctuating VOC loading (Bishop
et al, 1990; Weber and Hartmans, 1995). tmproved media
properties and reduced head loss can be achieved by sieving
the bed materials to reduce fines (Allen and Phatak, 1993).
It has been suggested that excessive head loss can be
prevented by naving 60% (by mass) of biofilter media composed
of particles greater than 4 mm in diameter (Corsi and Seed,
1994).
2 . 2 . 4 Microorganisms
Biofilters have frequently been regarded as "black
boxes" and are poorly understood with regard to the dynamics,
interactions and metabolism within the microbial populations.
However, a large population of microorganisms capable of
degrading the contaminants are necessary for successf ul
biofiltration. Most of the microorganisms found in
biofilters are bacteria and fungi (Leson and Winer, 1991;
Groenestijn and Hesselink, 1993).
T a b l e 2.1: Design parameters f o r b i o f i l t e r s .
Parameter Recommended Range
Retention Tirne
Surface Loading
F i l t e r Bed Temperature
F i l t e r Bed p H
F i l t e r Bed Moisture Content
I n f l u e n t Gas Relative Humidity
F i l t e r Media Porosity
Maximum Pol lu tan t Concentration
Maximum F i l t e r E l h i n a t i o n Capacity
B e d Depth
Pressure Drop
L i f e
> 15 s
Range 20-500 m3/m2*h
15 - 45 OC 7 - 8
50%-70% by mass, wet basis
0.5 - 2.5 m, 1 m average
< 0 -25 kPa ( 1 m depth)
2 - 5 years
Summarized From: Leson and Winer ( 199 1) ; Groenest i jn and Hesselink (1993 ) ; Swanson and Loehr (1997)
There has been l l m i t e d information published on the
nature and s i z e of t h e microbial populations found i n biofilters. Pearson (1992) reported t h e to ta l bacterial
count i n b i o f i l t e r s packed wi th heather ranged between 50
mi l l ion and 3 b i l l i o n per gram heather. T h e p i lo t - scafe
b i o f i l t e r was used to c o n t r o l odours £rom a b r o i l e r chicken
house. In laboratory-scale b i o f i l t e r s packed wi th peat and
seeded with bacter ia , Kiared et a l . ( 1996) found t h e bac te r i a
count ranged from one b i l l i o n t o one t r i l l i o n colony forming
u n i t s ( c fu) per gram, with a mean value of one b i l l i o n c fu
per gram. Lau et al. (1996) measured the total bacteria count
over a three month period in a full-scale biofilter used to
treat odours at a composting facility. The filter media
consisted of a mixture of yard waste compost, papes çludge,
wood waste and load soil. The filter media was not seeded
with microorganisms. Table 2.2 shows the total bacteria
count from the two sampling sites over a three month period
which ranged from 0.38 to 172 x 107 bacteria P e r g r a .
Table 2.2: Total bacteria counts (x107/g) from a full-scale biofilter.
Sampling Event
l(Nov) 2(Nov) 3(Dec) 4(Dec) 5(Jan)
Sample Site 1 5.0 5.8 2.2 O . 46 0.38 Sample Site 2 172 84 4.9 0.70 0.92 Average = 27.6 Standard Deviation = 56.9
(Lau et a1.,1996)
The degradation of poorly biodegradable compounds may
require inoculation of the bed material with microorganisms
that have been exposed to the contaminant. Also, faster
start-up times can be achieved with seeding biofilters.
Activated s ludge suspensions, specially cultivated
microorganisms and material from adapted biofilters have been
used as inoculum to enhance degradation of resistant
compounds and reduce acclimation periods ( Groenes t i j n and
Hesselink, 1993; Swanson and Loehr, 1997). For example,
Ottengraf et al. (1986) found that the degradation of
dichloromethane was achieved only after inoculation of the
bed with a culture of ~yphomicrobium sp.. Seeding of bed
media such as GAC, which does not contain indigenous
microbial populations, is required.
As with al1 biosystems an acclimation period is
experienced after start-up, when removal efficiencies
steadily increase until they reach a steady state. This
phenornenon occurs as the microbial population adapts enzymes
and degradative pathways to metabolize the contaminant(s).
For biofilters to meet regulatory requirements, they must
perform at high levels during the life span of the project.
Acclimation is an important issue during start-up and
restart-up after shutdown. Start-up acclimation periods of
days to weeks have been reported in the literature.
Restart-up acclimation times are generally shorter than
those during initial start-up ( Swanson and Loehr, 1997 ) . Once a biofilter process bas been established, its ab i l i ty to
recover from shut-downs and other disruptions has been shown
to be quite good (Martin and Loehr, 1996). For example , Ottengraf and van den Oever (1983) found when treating a
mixture of ethlyacetate, toluene, butylacetate and butanol
that once a steady-state was reached, the beds could last 2
weeks between gas loading, without a reduction in removal
efficiency. Deshusses et al. (1996) found, when treating a
mixture of MEK and methyl isobutyl ketone (MIBK), that a prompt and efficient treatment can be readily re-established
after a 5-day starvation period. To speed up acclimation
upon restart-up, the biofilter media should be aerated, kept
moist and at near-optimal temperature during shut-doms
(Martin and Loehr, 1996).
Gibson (1995) investigated the ability of compost-based
biofilters to perform under discontinuous and fluctuating
loading conditions. Using dimethyl disulphide (DMDS ) as the
contaminate in laboratory scale biof ilters , Gibson ( 1995 )
cycled the loading between one hour of high loading (51 ppmv)
and one hour of l m loading ( 13 ppmv) . Each experiment ran for approximately 52 hours allowing for 26 complete two-hour
cycles. He used three different compost mixtures in the
biofilter: compost which had never been exposed to DMDS
(virgin); compost which had demonstrated DMDS removal
capacity but had sat without DMDS or air loading for a period
of one month (stagnant for 1 month), and; stagnant for one
month compost which had been exposed to the fluctuating load
condition and then sat dormant for three days (stagnant for 3
days ) . Two runs were conducted with each media type. Gibson
found that the virgin compost had a removal efficiency of
less than 3% for both runs. The removal ef f iciency
increased £ r o m 1.3% to 35% over the first run and from 17% to 30% over the second run for the compost that had been
stagnant for one month. The removal eff iciency ranged £rom
33% to 45% for run one and from 21% to 30% for run two, for
the compost that had been stagnant for 3 days. This
experhent demonstrated that compost-based biofilters can regain removal capacity quickly even after one month of
inactivity.
~ainville ( 1996) investigated the ef f ect of sterilizing
the media in compost-based biofilters. Three biofilters were
operated with an air flow of 17 L h i n and a butyric acid
concentration of 50 ppmv for 85 days. ~uring the experiment,
the butyric acid concentration was lowered to 25 ppmv on
several occasions to examine the effect of cyclic loading on
each biofilter, and reduced to zero to ascertain the response
of each biofilter to this condition. One of the biofilters
was packed with non-sterile media, while two of the
biofilters were sterilized by autoclaving. The removal
efficiency of the non-sterile biofilter ranged from 30% to
85%, averaging about 50% to 60% over the study. The cyclic
loading appeared to have no negative effect on the removal
efficiency of the non-sterile biofilter. During the three
days of zero mass loading the non-sterile biofilter's
butyric acid outlet concentration dropped to about 10 ppmv.
When butyric acid loading was resumed, the removal of butyric acid rapidly returned to previous levels. The sterile field was maintained for about 6 days in the sterile biofilters. The sterile biofilters responded similarly to the cyclic changes in butyric acid concentration and zero mass loading.
However, the sterile biofilters had a butyric acid outlet concentration about 5 to 10 pprnv higher than the non-sterile
biofilter. A t day 69, one of the sterile biofilters was re- sterilized and the concentration of butyric acid leaving the biofilter rose until it aimost reached the inlet
concentration of 5 0 ppmv. At day 76 the re-sterilized biofilter was inoculated with fresh compost and by day 79 the butyric acid was being removed efficiently again. When the
three biof ilters were dismantled, large clumps of fungal
growth were obsesved on the top surface of the filter media and centre of the compost mass. This experdent demonstrated
that sterilization of the filter media in a compost-based biofilter will lower the removal efficiency, however,
reseeding of the sterilized media will rapidly restore the removal ef f iciency . Further, this study provides strong
evidence that biological activity was the mechanisrn for removal of the butyric acid.
2 . 2 . 5 Nutrients
Organic-based filters usually contain sufficient quantities of inorganic nutrients in available form to
support microbial activity (Leson and Winer, 199 1 ) . However, n u t r i e n t availability can be a factor in biofiltration performance. For example, Seed (1995) reported
nutrient availability as a limiting factor for effective biofiltration in some compost-based filter media. Poor
toluene removal was due to a lack of available nitrogen in composted leaf and yard waste and composted bark filter media. In another study, Morgenroth et al. (1996)
investigated the hexane removal in a compost biofilter.
Removal efficiencies of 80% were achieved after one month of
operation. However, after three months of operation the
removal efficiencies had dropped to about 50%. Addition of a
concentrated potassium nitrate solution (131 g/l) caused a
sustained increase in removal efficiency front about 50% to
99%. The researcher hypothesized that nutrient availability
(nitrogen) had limited the performance of the biofilter
(Morgenroth et al. 1996). Weckhuysen (1993) found enhanced
degradation of butanal after addition of inorganic nutrients
to a bark based biofilter. Gibson (1995) found enhanced
degradation of dimethyl sulphide after addition of a yeast
extract to a compost-based biofilter.
Clearly, the issue of nutrient availability and nutrient
supplementation is important in biofilter operation, however presently there are no guidelines available regarding the
amount of nutrients needed in biofilters (Swanson and Loehr,
1997). When i n e r t media like GAC is used it is necessq to provide nutrients to the biofilter.
2 . 2 . 6 Filter Bed pH
The preferred range of pH for most microorganisms found
in biofilters is 7-8 (Leson and Winer, 1991). The
degradation of some compounds, particularly chlorinated
hydrocarbons, can produce acidic by-products which lower bed
pH. Lowering of the bed pH can inhibit or destroy the
microbial population, subsequently reducing or eliminating
the filter's degradation capacity. To prevent t h i s , chemical
buffers such as limestone, calk, marl and oyster shells can be added to the bed media. Also, chemical buf fer solutions
can be added to the irrigation water.
2 . 2 . 7 Moisture Control
Moisture con t ro l has been iden t i f i ed as t h e s i n g l e most
important parameter i n b i o f i l t e r operation. Optimal
b i o f i l t e r media moisture content ranges £rom 40 t o 60% (by
w e t mass) (Leson and Winer, 1991 and Groenest i jn and
Hesselink, 1993)- A dry f i l t e r media causes reduced
microbial a c t i v i t y , as w e l l as contract ion and consequent
media cracking, r e s u l t i n g i n reduced r e t e n t i o n t imes (Swanson
and Loehr, 1997)- Simi la r ly , too much moisture i n t h e
b i o f i l t e r media w i l l r e s u l t i n higher headloss, plugging of
pore spaces, c rea t ion of anaerobic zones and n u t r i e n t washing
from t h e b i o f i l t e r media (Swanson and Loehr, 1 9 9 7 ) -
~ a i n t a i n i n g optimal moisture content has been
t r a d i t i o n a l l y approached through: humidification of incoming
a i r through t h e use of a packed water-tower o r adding w a t e r
mist; d i r e c t water add i t ion to t h e sur face of t h e b i o f i l t e r
media through a spray-like i r r i g a t i o n system; OS a
combination of both-
2 - 2 - 8 ~limination Rates and Flow Rates
The waste-gas flow rates Vary depending on t h e b i o f i l t e r
application. Waste-gas flow rates t y p i c a l l y range f rom 1 , O 00
t o 150,000 m 3 / h (Leson and Winer, 1 9 9 1 ) .
The e l h i n a t i o n capac i ty (EC) of a f i l t e r bed is t h e
mass of t h e contaminant ( o r carbon) removed p e r u n i t volume
of bed material per u n i t of t h e . The mass loading rate to
the f i l t e r is defined as the mass of contaminant per u n i t of
bed mater ia l per u n i t t h e . The EC and mass loading r a t e are
usually reported as bed-averaged values, harever, they should not be expected t o be uniform over t h e b i o f i l t e r depth- The
b i o f i l t e r s i z e requirement f o r a waste gas a p p l i c a t i o n is a
function of the EC, mass loading capacity and contaminant
concentration. Degradation rates for common air pollutants
typically range from 10 - 100 g/mî/h (Leson and Winer, 1991). Maximum concentrations of biodegradable contaminants are in
the range of 1-5 g/m3 (Groenestijn and Kesselink, 1993).
The surface loading or "face velocity" will also affect the
filter size. Upper limits on surface loading exist due to bed-drying concerns. Maximum surface loads with efficient
moisture control systems have been reported at 200 m/h
(Swanson and Loehr, 1997) and 500 m/h (Leson and Winer,
1991) . Although, this data provides design guidelines,
sizing of the filter is typically based on treatability
studies. The required size for a full-scale filter then can
be determined by scaling-
2.3 Treatability of MEK and Toluene
2.3.1 Chernical and Physical Properties of MEK
and Toluene
As discussed, a contaminant's chemical and physical
properties determine its availability in the biofilm. Some
of the relevant chemical and physical properties of MEK and toluene are listed in Table 2.3. Methyl ethyl ketone is very water soluble and the Henry's Law Constant is 5 orders of
magnitude below the upper limit of 10 (dimensionless)
recommended for biofiltration- mile toluene is only
slightly water soluble, the Henry's Law Constant is 3 orders
of magnitude less than the recommended upper limit. The
chemical and physical properties of MEK and toluene indicate they would be good candidates for biofiltration.
Table 2.3: MEK and Toluene chemical and physical properties.
Property MEK Toluene
Molecular Formula C4H80 C7H8
~oiling Point (OC @ 760 mm Hg)
Molecular Weight (ghole )
Log Octanol/Water Partition 0.29 Coefficient
Water Solubility (rng/l @25 OC)
Vapour Pressure (mm Hg @25 OC)
Henry's Law Constant (atm/m3/mole)
(taken from the Handbook of Environmental F a t e and Exposure Data for Organic Chemicals, Volume II, Solvent, 1990)
2.3.2 MEK and Toluene Biodegradation and B i o f i l t r a t i o n S t u d i e s
MEK and toluene are both known to be readily
biodegradable in soi1 and ground water (Howard, 1990 ahb).
Toluene has been shown to be biodegradable by both bacteria and fungi. Chang et al. (1993) identified two Pseudomonas
species (fragi and fluorescens) which can use toluene as the
sole source of carbon and energy. Pseudomonas putida
(biotype B), a commercially available bacteria is also
capable of utilizing toluene as a sole carbon and energy
source (Robinson et al., 1990). White-rot f ungus,
Phanerochate chrysosporium, has also been show to
efficiently degrade toluene (Yadav and Reddy, 1993).
A review of the biofiltration studies involving MEK
and/or toluene follows. Only biofiltration studies using
organic materials such as compost or peat as the media are
reviewed. The majority of the studies involve laboratory-
scale biofilters. No litesature on the use of pilot-scale
or full-scale biofilters to remove either MEK or toluene as
the sole contaminant were found.
In a series of experiments Deshusses et al. (1995, 1996)
and Deshusses (1997) treated air streams containing MEK or
mixtures of MEK and MIBK (methyl isobutyl ketone) in
laboratory-scale, compost-based biofilters to study:
i) The experhental evaluation of a diffusion reaction
mode1 for the determination of both steady-state and
transient-state behavior.
ii) ~ransient-state behavior removing a mixture of MEK
and MIBK during start-up, step changes in pollutant loading, responses to pollutant pulses and restarting
after starvation.
iii) Transient-state behavior with MEK as the single
pollutant during start-up and with hexane, l-propanol,
MIBK and acetone as puise polïutants.
In these experiments MEK was readily biodegraded. Typicai
operational conditions with MEK as a single pollutant were
an inlet concentration of approximately 0.5 g/rn3, flows of
0.2-0.4 m3/h and surface loadings of 40-80 m/h. Removaï
rates of greater that 95% for MEK were reported. During
the start-up experhent with the inlet concentration of MEK
set at 0.5 g/m3 and the downward gas flow rate of 0.7-0.8
m3/hr after 75 hours of operation the biofilter achieved
complete removal of MEK (Deshusses, 1997). Start-up
20
experiments with inlet concentrations of MEK and MIBK at
0.53 and 0.56 g/m3, respectively, and an airflow rate of 0 .2
d / h , demonstrated 99% removal after 4.5 days of operation
(Deshusses et al,, 1996) .
Experiments with mixtures of MEK and MIBK, where either
the MEK or MIBK concentrations and flow rate were varied,
demonstrated that the biofilter adapted rapidly to new
operating conditions (Deshusses et al,, 1996 ) . In most
cases, about 2-5 hours were required after the step changes
before a new steady state was established. Experiments with
a mixture of MEK and MIBK, where pollutant pulses of MEK or
MIBK were added to the biofilter bed, demonstrated tfiat when
MEK was pulsed, both MEK and MIBK biodegradation rates were
reduced, while MIBK pulses had very Little influence on the
biofilter performance.
In the starvation experiment the biofilter received a
constant feed of MEK and MIBK at 0.34 and 0.65 g / d ,
respectively, with an airflow rate of 200 L/h. After an
unspecified the, both the airflow and pollutant supply were
stopped for 5 days, after which the system was restarted
under the same conditions prior to stoppage. Upon
restarting, immediate and efficient biodegradation was
reestablished (Deshusses et al., 1996).
The dynamic response was measured on a biofilter
receiving a constant feed of MEK from 1.3-1.55 g/d, and a
superficial velocity of about 40 m/h, to pulses of either
hexane, 1-propanol, M I B K , acetone or a mixture of 1-propanol,
MIBK and acetone (Deshusses, 1997). Very different responses
of the biofilter to the pulses of these solvents were
obsenred . Hexane was neither sorbed to the bed nos
biodegraded to any significant extent. Acetone and 1-
propanol were both readily biodegraded at greater than 95%
and caused no inhibitory effect on MEK removal at greater
21
Seed (1995) a lso studied the e f f e c t of toluene
introduction on xylene removal i n b i o f i l t e r s packed with
composted municipal s o l i d waste and p e r l i t e . One f i l t e r was
operated w i t h an average xylene i n l e t concentration of 62
ppmv for f ive days before toluene was introduced with an
average i n l e t concentration of 7 3 ppmv. Xylene removal
eff ic iency dropped from 80% t o 72% a f t e r toluene addition.
Toluene removal ef f ic iency was 89%.
Hwang and Tang (1996), using toluene as t h e contaminant,
compared t he performance of b i o f i l t e r s packed with mixtures
of chaff/compost, diatomaceous earthkompost and granular
act ivated carbon/compost. A removal ef f ic iency of 90% was
achieved when the b io f i l t e r s were operated with an i n l e t
concentration of 0.9 g/m3 of toluene and a retention t h e
(RT) of 2 - 5 minutes. However, when t h e RT was 2 minutes the
removal eff ic iency dropped below 90%.
Kiared et a l . (1996) studied t he e l h i n a t i o n of toluene
and ethanol i n a b i o f i l t e r packed w i t h a bed of peat and
i n e r t par t ic les . The b i o f i l t e r was inoculated with speci f ic
micro-flora able t o degrade toluene and ethanol. T h e ethanol
i n l e t concentration w a s maintained a t 1.89 g/m3 throughout
the study, w h i l e t h e toluene concentration ranged from 0.75
t o 3.76 g/m3. The superf ic ia l veloci ty w a s held constant a t
70.7 m/h during t h e experhent and t he average retent ion t h e
was 51 seconds. The f i l t e r w a s operated over a 55 day
period. The removal efficiency f o r ethanol w a s about 80% and
t h e removal ef f ic iency for toluene w a s 70% during the f i r s t
month of operation. After t h i s period, humidification was
stopped f o r 20 days and t h e removal ef f ic iency fo r toluene
ranged £rom 40%-50%. The ethanol removal eff ic iency during
t h i s 20 day period was not reported. When t h e humidification
was restarted the removal eff ic iency fo r toluene returned t o
70% . 23
These e x p e r h e n t s demonstrate t h a t compost- o r peat-
based b i o f i l t e r s are capable of e f f i c i e n t l y t r e a t i n g w a s t e
gas streams containing toluene o r mixtures of toluene and
ethanol o r xylene.
P i lo t - sca le compost b i o f i l t e r s have been shown t o be
e f fec t ive i n rernoving VOCs from gas streams a t w a s t e
treatment f a c i l i t i e s . Ergas e t a l . (1995) measured t h e
removal of six VOCs commonly found in w a s t e w a t e r , including
toluene, f r o m a p i lo t - sca le compost b i o f i l t e r a t a waste
water t reatment f a c i l i t y . The b i o f i l t e r s w e r e operated with
gas f luxes ranging frorn 18 t o 108 m/h and with t h e VOC
concentrat ions i n t h e range of 100 t o 5,000 ppbv. The
removal of t h e VOCs averaged grea te r than 80% during t h e 8.5
month f i e l d study. Webster and Devinny (1996) measured t h e
removal of a range of VOCs, including MEK and toluene, from
bench- and p i lo t - sca le compost b i o f i l t e r s a t a w a s t e water
treatment f a c i l i t y . T h e average i n l e t concentra t ion f o r MEK
and toluene w e r e 35 ppbv and 26 ppbv, respec t ive ly . I n t h e
bench-scale biof ilters t h e removal ef f i c iency f o r MEK was
87%-99% and 97% f o r toluene. In t h e p i l o t - s c a l e b i o f i l t e r ,
MEK removal was not measured, while t h e toluene removal
e f f i c i e n c i e s were as follows: 57% with a RT of 30 seconds;
24% with an RT of 4 5 seconds, and; 89% with an RT of 70
seconds.
2.3.3 Canadian General Tower S t a c k D a t a
Table 2.4 summarizes t h e s tack and emission d a t a f o r t h e
dry laminator a t Canadian General Tower. This d a t a was
provided by Canadian General Tower. The dry laminator has
four exhaust stacks, with t h e est imated d s s i o n
concentrat ion from t h e s tacks ranging from O t o 3.53 g/m3 f o r
MEK, and O to 1.77 g / d for toluene. T h e cornbined
concentration for MEK and toluene ranges from 1.06 t o 5.3
g/m3 . Biofiltration has been shown to be effective in
treating waste gases with concentrations of biodegradable
contaminants up to 5 g/m3 (Leson and Winer, 1991;
Groenestijn and ~esselink, 1993).
Table 2.4: Typical dry laminator stack and mission data.
Stack Emission Contaminant Concen . Total VOC Flow No. Source Concen .
( d m 3 ( d m 3 ) (m3/s)
6 Coater MEK 0.71 1.06 2.36 Exhaus t Toluene 0.35
7 1 .R. Oven MEK 3.33 4.99 1.50 Toluene 1 . 66
8 Hot Air MEK 3.53 5-30 2.83 Oven Toluene 1.77
Compost-based biofilters have been show to be effective
in treating waste gas streams which contain either MEK or
toluene. Also, they have been effective in treating waste
gas streams which contain mixtures of VOCs including MEK
and/or toluene- No literature was found on using
biofiltration to treat a waste gas containing a mixture of
only MEK and toluene. Biofiltration would appear feasible
for treating the dry laminator waste gas at Canadian General
Tower because :
i) the contaminants, MEK and toluene, are biodegradable;
physical properties for biofiltration;
iii) mission concentrations of MEK and toluene in the
dry laminator waste gas are w i t h i n acceptable limits for
biofiltration.
As with most industrial applications of biof iltration, a
pilot study will be the best means to determine whether a
compost-based b i o f i l t e r will be able to effectively t rea t the
dry laminator waste gases.
3 - 0 Materials and Methods
3 - 1 Experimental Apparatus
The s tudy involved passing a sample of waste gas from
t h e coater exhaust hood s tack ( s t ack number 6 ) through a
p i lo t - sca le b i o f i l t e r system. The waste gas from stack
number 6 was chosen because the MEK and toluene
concentrat ions w e r e t h e lowest. It was planned t h a t i f the
b i o f i l t e r w a s successful a t removing MEK and toluene from
s t ack number 6 , then waste gas from t h e s tacks 7 and 8 which
had higher concentrat ions of MEK and toluene would be t r ea t ed
i n t h e b i o f l l t e r , This was no t done because t h e study was
cut-of f when t h e dry laminator was shut-down f o r an extended
period f o r modifications.
3.1.1 B i o f i l t e r System
Figure 3.1 shows a schematic of t h e b i o f i l t r a t i o n
system. The b i o f i l t e r was constructed by t h e author i n h i s
home workshop of 5 / 8 " polyboard, made from recycled
polyethylene, polypropylene and wood. This mater ia l was
choosen as it was inexpensive, could be cut and shaped with
hand too l s and w a s rot r e s i s t a n t . The b i o f i l t e r consis ted of
t h r e e s tages housed i n s i d e a cabinet. Each s t age measured 30
cm by 60 cm by 37 cm, with the top open and t h e bottom made
of perforated s t a i n l e s s steel ( 3 mm diameter holes on 5 mm cen t re s ) t o allow t h e gas to pass through. The s tages were
placed i n a cabine t which measured 153 cm by 62 c m by 40 cm,
so t he re was a 20 cm plenum above t h e top s t age and a 10 cm
plenum above t h e middle and bottom stages. Below t h e bottom
s t a g e there was also 20 cm plenum. The f r o n t door of t h e
cabinet was a t tached with bolt- latches and sealed a i r - t igh t
wi th 1" by 1/4" neoprene weather s t r ipp ing and duct tape. To
prevent air f r o m by-passing the b i o f i l t e r media, s i l i cone
caulking was used to seal the sides and back of each
biofilter stage to the walls of the cabinet. Neoprene
weather stripping was used to create an air-tight seal
between the front of each stage and the door of the cabinet.
Each biofilter stage was lightly packed with screened
municipal compost, containing 50% w a t e r by mass to a depth of
24 cm, for a total bed depth of 72 cm. The resulting media
volume per stage was 53.3 litres, the total filter bed volume
was 159.9 litres.
The waste gas sample was drawn through the biofilter
with an explosion-proof regenerative blower (EG&G Rotron
model EN/CP 101). The waste gas sarnple was taken from the
positive pressure side of stack fan number 6, and returned to
the negative pressure side of this stack fan. The flow rate
was controlled by a bal1 valve and measured with an in-line
rotameter (ûmega Engineering model FL-1603A). One inch steel
piping was used in the waste gas supply system.
ft was originally intended that the waste gas would be
humidified by bubbling it through a column of w a t e r . This
would have required the waste gas to have been blown through
the biofilter, placing it under positive pressure. The waste
gas stream contained methylene diphenyl isocyanate (MDI), a
respiratory sensitizer and designated substance under the
Occupational Health and Safety Act of Ontario. Due to
concerns about MD1 leaking from the biofilter, CGT required d the biofilter to be operated under negative pressure. This
made use of the humidification column impossible, so it was
decided to proceed using only the intemal irrigation system
to maintain the required moisture in the bed.
T h e interna1 irrigation system consisted of four
sprayheads located 5 cm above each stage was used to keep the
biof ilter beds moist. The sprinkler system was constructed
from 1/2" and 3 / 4 " schedule L copper tubing and solid cone
spray tips (Delavan CE-1 ) . Wet boom standard thread eyelet
bodies (Delavan part number 36977-1) were used to attach
spray tips to the copper piping. Each section of the
sprinkler system was fitted with a shut-off valve to control
the amount of water being sprayed on each biofilter stage.
The water w a s supplied to the sprinkler system from a 50
litre reservoir by a 1/2 horse power çump pump. The source
of the water was City of Cambridge tap water. The pump was
initially manually operated and then operated with a multi-
circuit programmable timer/controller (Cole-Palmer) with a
resolution of one second. The sprinkler system w a s adjusted
to supply approximately 2.7 litres of water per minute per
stage. The waste water which collected in the bottom of the
biofilter was removed to a 5 gallon pail using a tubing pump
(MasterFlex LS Fixed Drive Pump) and L/S 25 Tygon tubing
(MasterFlex). The waste water was not recycled as it
contained suspended solids which would have clogged the pump.
3.1.2 Relative Humidity and Temperature Measurement
T h e w a s t e gas inlet and outlet relative humidity and
temperature were measured using a relative humidity and
temperature transmitter (General Eastern RHT-5-1-D). A
transmitter was placed in the top and bottom plenums of the
biofilter as shown in Figure 3.1. When installed, the tip of
the transmitter protruded 20 cm into the biofilter. Relative
hddity and temperature were recorded using a datalogger (Datataker DT 100).
3.1.3 Headloss Measurement
pressure drop through the biofilter was measured using a water-filled U-tube manometer. The pressure taps were
located in the top and bottom plenums of the biofilter.
3.2 Biofilter Media
3.2.1 Source
The filter media used was mature municipal compost from
t h e C i ty of Guelph's W e t - D r y F a c i l i t y . The compost w a s
composed of a mixture of leaf, yard waste, s t raw, manure,
municipal s o l i d w a s t e and wood ch ips .
3.2.2 Media Preparation
The compost w a s s t o r e d i n e i g h t f i v e ga l lon p a i l s for
three weeks p r i o r t o use. Three days p r i o r t o mixing the
compost w i t h w a t e r , a sample front each p a i l w a s t aken t o
determine t h e moisture conten t of t h e compost, The average
moisture content f o r t h e e i g h t samples was 26.9% w a t e r by
mass with a standard dev ia t ion of 1.4%. The f i l t e r media
was weighed i n batches then placed i n a f ive ga l lon p a i l for
mixing w i t h t a p w a t e r . The w a t e r w a s then weighed and t h e
appropr ia te amount of w a t e r was added with a hand he ld
spraypump u n t i l t h e f i l t e r media contained 50% water by mass.
The compost and w a t e r were mixed together us ing a hand
t rowel . The w e t t e d compost w a s loaded i n t o t h e f i l t e r s t a g e s
rnanually and l i g h t l y packed down after about 6 cm of media
w a s added u n t i l a depth of 24 c m w a s achieved. ~pproximately
28.5 kg of f i l ter media w a s added t o each s tage .
3.3 Analytical Methods
3.3.1 Gas Sampling
A gas chromatograph ( G C ) , SRI8610 GC, equipped wi th a
flame i on i za t ion d e t e c t o r ( F I D ) was used t o determine t h e MEK
and to luene l e v e l s i n t h e waste gas Stream. All samples
were drawn manually from the biofilter with a 1 ml gas tight
30
RH/Temp. Sransmitter
Rotameter
Stack No.
Biof ilter S t a q e s
Municipal Compost
Blower n
Air Sarnpling Ports
Effluent Air Returned to Stack No, 6
Figure 3.1: Schematic of experimental b io f i l t e r system.
syringe fitted with a gas tight valve (Hamilton) and then
manually injected into the GC. The samples were O - 5 m i in
size. Typically 3 to 7 samples were taken from a given
sampling port, with the average value being reported. Table
3.1 lists the GC-FID parameters used during the analysis. The
cycle t h e between samples was about 15 minutes.
Gas sampling ports were located in the 3 plenums above
each biofilter stage and in the plenum below the bottom
stage. The sampling ports were made of 0.25" by 2 -25" brass
bulkhead unions fitted with Teflon coated silicone septa.
Calibration curves were prepared using certified gases
containing a mixture of MEK, toluene and nitrogen ( Matheson
Gas Products Canada, supplier). The first set of calibration
Cumes was prepared prior to the start of the study and the
second set was prepared after the 11 day shut-dom of the dry
laminator when the GC had not been used for almost one month.
Data for the two sets of calibration curves are located in
~ppendix A. Table 3.2 lists the component concentrations of
the three certified gases. A sample from each certified gas
was injected into the GC before and after each set of
biofilter samples were taken. The CG-FID was considered to
be operating within acceptable parameters if these samples
were within +/- 10% of the calibration curve. The data for
these calibration checks are located in Appendix B.
3.3.2 Carbon D i o x i d e Analysis
A portable infra-red detector (LI-COR 6262) was used to
measure the carbon dioxide levels in the biofilter gas
stream. The detector was calibrated prior to use with gas
standards of 100, 250, 500, 750 and 1000 ppmv of carbon
dioxide. The detector calibration was checked after sampling
was completed using calibration gases containing 330 and 368
ppmv of carbon dioxide. The detector was connected on-line
32
Table 3.1: GC-FID settings.
Parameter Setting
Colurnn Type Restek MXT-5 length: 30 m diameter 0.53 mm ID
Column Flow
Oven Program
carrier gas: UHP Helium flow rate: 6.1 rnl/rnin
Initial Temp = 40 OC Hold at 40 OC for 1 min Ramp 15 oC/min till 110 OC Kold 110 OC for 1 min Return to 40 OC Run thne 6.67 min
Table 3.2: Components of certified gas standards.
Gas Component Concentration
Low Concentration MEK 18.8 +/- 0.9 ppmv (2000 PSIA) Toluene 21.7 +/- 1.1 pprnv
Nitrogen balance
Medium Concentration MEK 181 +/- 4 ppmv (1500 PSIA) Toluene 184 +/- 4 ppmv
Nitrogen balance
High Concentration MEK 1835 +/- 37 ppmv (150 PSIA) Toluene 1823 +/- 36 ppmv
on days 58, 62, 63, 72 and 78 of operation. A gas stream was
drawn through the detector using a tube pump at a rate of 0.9
L/min. The 3as stream was drawn from eithes the top or
bottom plenums through pressure taps used to measure
headloss. This detector was connected alteratively to the
top and bottom plenum for approximately 30 minutes. Readings
from the detector w e r e recorded every 5 minutes. The
detector was connected while the dry laminator was operating
and after it was shut-dom.
3 . 3 . 3 Media Analpsis
3.3.3.1 Moisture Content and pH
The moisture content of the biofilter media was
calculated by mass determinations of media samples before and
after oven drying at a temperature of 103 OC for 24 hours.
The pH of the biofilter media was determined by
preparing a paste slurry of the filter media and using a
surface pH probe (Fisher Scientific combination probe with
Accumet 92. pH/ion meter).
A sample was drawn from each stage on days 20, 37, 51
and 120 of operation and the moisture content and pH were
determined. The biofilter was dismantled at the end of the
study and two samples were taken from each stage. The
moisture content and pH were then determined on two sub-
samples £rom each sample, for a total of four samples from
each stage.
3-3.3.2 Nutrients
The analysis for nutrient levels, pH and moisture
content in the filter media was performed by Analytical
Services Laboratory , Land Resource Science, University of
Guelph. Two media samples were collected from each stage at
the end of the experiment and placed in plastic samples bags
and then transported directly to the laboratory. Two samples
were also submitted from the original compost batch, which
had been stored at roorn temperature in a sealed 5 gallon
pail .
Total nitrogen, phosphorus, potassium, calcium and
magnesium were determined from sub-samples of oven-dried
compost using sulphuric acid digestion. A Technicon Auto 34
Analyzer was used t o measure nitrogen and phosphorus
concentrations. Atomic absorption spectrophotometer was used
i n determining potassium leve l s .
Ammonium (Ml4-N) and n i t r a t e (NOî-N) ni t rogen were
determined from a sub-sample of material placed i n a 2 M
so lu t ion of KCL and shaken f o r 30 minutes, The s o l u t i o n was
then f i l t e r e d through a Whatman f i l ter paper (number 4 2 ) .
Ammonium and n i t r a t e l e v e l s i n the f i l t r a t e were detemined
using a Braun and Lubbe Traacs 800 autoanalyzer.
The moisture content and p H were determined £rom a sub-
sample using similar methods as described above.
3 . 3 . 3 . 3 Microbial Profile
The ana lys i s of t h e microbial p r o f i l e was performed by
t h e Microbial Laboratory , Laboratory Services Division of t h e
University of Guelph. Five samples of f i l t e r m e d i a were
collected from each stage a t the end of t h e study. The
samples w e r e placed i n sterile specimen b o t t l e s and
t ransported d i r e c t l y t o t h e laboratory f o r ana lys i s . The
samples w e r e analyzed t o determine t h e aerobic colony count and i den t i fy t h e predominant types of microorganisms present .
3.3.3.4 Accessing the B i o f i l t e r Media
Due t o t h e presence of methylene diphenyl isocyanate
(MDI) i n t h e waste gas stream, a designated substance under
the Occupational Health and Safety A c t of o n t a r i o , c e r t a i n
precautions w e r e required before the b i o f i l t e r cab ine t could
be opened. When opening the b i o f i l t e r t o sample t h e media,
an a i r supply respirator, covera l l and gloves had t o be worn
to prevent i n h a l a t i o n o f , o r sk in contact with t h e MDI.
3 . 4 fnsect Identification
The i d e n t i f i c a t i o n of t h e f l y i n g i n s e c t s t h a t were found
breeding in the b i o f i l t e r was perfomed by t h e P e s t
Diagnostic ~ l i n i c , Labora toq Services Division of t h e
University of Guelph. A sample of t h e i n s e c t s co l l ec ted from
the tubing connecting the U-tube manometer t o t h e b i o f i l t e r
w a s sen t f o r ana lys i s .
3 - 5 Chemical ~ o a d i n g
The b i o f i l t e r was connected t o the c o a t e r exhaust hood
stack and operated continuously for 156 days. T h e biof i l t e r
was operated under t h r e e d i f f e r e n t condit ions:
i) "Chemical Loading", when t h e dry laminator w a s
operating and MEK and toluene were i n t h e w a s t e gas
stream. The chemical loading per iod could be fu r the r
divided i n t o periods of production loading and non-
production loading. During production chemical loading,
t h e dry laminator would have been operat ing a t normal
capacity w i t h t h e highest concentrat ions of MEK and
toluene i n t h e waste gas stream. The per iods of non-
production chemical loading would include times such as
product change over or mechanical breakdoms and januning
of t h e machine when t h e concentrat ions of MEK and
toluene would be considerably lower than during
production.
ii) " N o Chemical Loading" , when air was passed
through t h e biofilter and t h e bed was kept moist. T h e
dry laminator t y p i c a l l y operated f r o m 4 t o 16 hours per
day from Monday t o Friday and w a s non-operational on t h e
weekends. The dry laminator w a s a l s o non-operational
f o r periods exceeding 48 hours f o r maintenance and r e p a i r work, lack of production and holiday shu t doms.
iii) "Stagnant", when no f low at al1 was passed through the biofilter .
The concentration of MEK and toluene during production
chemical loading was measured on 33 different days of
operation. The average MEK inlet concentration during this
t h e period was 193 ppmv (0.57 g/rn3) with a standard
deviation of 24 ppmv (0 . 07 g/m3) and a range of 142 to 244
ppmv (0.42 to 0.72 g/m3). While t h e average toluene inlet
concentration was 161 ppmv (0.61 g/m3) with a standard
deviation of 25 ppmv (0.09 g/m3) and a range of 122 to 228
ppmv (0.46 to 0.86 g/m3). The concentration of MEK and
toluene in the waste gas stream was effected by the width of
the product being run, speed of the dry laminator,
temperature of the coater and the type of glue being used.
The dry laminator waste gas also contained methylene
diphenyl isocyanate ( M D I ) . MD1 is a component of the
adhesive used. The concentration for MD1 in the waste gas
stream was less than 50 ppbv.
The production hours of the d r y laminator, or production
chemical loading periods, were obtained from t h e Company to
estimate periods of chemical loading on the biofilter. The
periods of non-production loading were not available. Table
3.3 shows the sumrnary of the production chemical loading
periods during the study. Figure 3.1 depicts the production
chemical loading for each day over the duration of the study.
The total hours of production chemical loading during
the months of October and November, 1997, were 253.6 and
164.9 hours , respectively . After this period production on
the dry laminator dropped from t w o eight-hour shifts per day
to only one eight-hour shift per day. This resulted in a
s igni f icant drop i n t h e chemical loading of the b io f i l t e r .
The t o t a l hours of production chemical loading during the
months of D e c e m b e r , 1997 and, January and February, 1998,
w e r e only 54.9, 7 8 . 4 and 110.8 hours, respectively.
Comparing t h e average chemical loading per day for these t w o
periods show t h e impact of the reduction i n production. The
average hours of production chemical loading per day for t he
months of October and November was 6.9 hours per day and only
2.7 hours per day fo r t h e months from December t o March.
Table 3 .3 : S m a r y of production chemical loading.
Month Total Hours Days of Days of Average Pro. Chernical Loading No ~oading Hours/Day Loading* Pro. Chem.
Loading* *
October 253.6 20 11 12.7 November 164.9 18 12 9.2 Decernber 54.9 12 19 4.6 January 78.4 17 14 4.6 February 110.8 18 10 6.2 March 9 . 3 2 1 4.6 ---------------------------------------------------------- Totals 671.9 87 67
*(Pro. Chem.Loading = Production Chemical ~ o a d i n g ) ** average hours/day of production chemical loading on t h e days that t h e dry laminator w a s operated
4.0 Results and Discussion
4.1 Flow R a t e s
The air f low r a t e through t h e b i o f i l t e r was varied
through t h e study t o determine t h e e f f e c t on the removal
e f f ic iency . Table 4.1 shows t h e a i r f low rates used during
t h e study. The e f f e c t of t h e a i r f low rate on removal
e f f i c i ency is discussed l a t e r .
Table 4.1: Airflow r a t e s during t h e study.
Day of Operation F l o w Velocity (m3/h) ( m m
4 . 2 Temperature and Relative Humidity of the Waste Gas
Tables 4 .2 and 4.3 show t h e temperature and r e l a t i v e
humidity leve ls of t h e i n l e t and o u t l e t gas stream measured
during t h e study. Data is missing for several periods during
t h e study due to problems w i t h t h e datalogger. T h e
temperature of t h e waste gas during t h e s tudy was within t h e
acceptable range of 15 - 45 OC f o r operating a b i o f i l t e r .
The waste gas was not humidified p r i o r t o enter ing t h e
biofilter. During t h e period of operation f r o m day 1 t o 21,
t h e i n l e t a i r stream average r e l a t i v e h d d i t y (RH) was
higher than during the other periods of measurement and the
average o u t l e t RH was above t h e detect ion limit of the probe.
This could be explained by t h e fact that during t h i s period
t h e i r r i g a t i o n system was operated f o r a longer period of
t h e each day than during t h e o the r periods. Also, on day 14
of opera t iona l error w i t h the pump timer r e s u l t e d i n about 3-
4 t imes t h e n o m a l level of w a t e r being ernitted from t h e
i r r i g a t i o n system. During t h i s period t h e i n l e t and/or
o u t l e t probes may have become sa tu ra t ed , which would g ive
readings above t h e de t ec t ion l i m i t of 95%. During t h e
remaining periods t h e i n l e t a i r stream RH ranged from 63%-69%
and the o u t l e t a i r stream RH ranged from 83%-85%. T h e
i n f l u e n t gas relative humidity was below t h e recommended
range of 80%-100%. This shows t h a t t h e waste gas picked up
..,isture from t h e b i o f i l t e r bed.
Table 4.2: Temperatures of t h e i n l e t and o u t l e t gas stream.
Days Number I n l e t Temp. (OC) Out le t Temp.(oC) Obs . Mean Std D e v M e a n Std D e v
T a b l e 4 . 3 : Relative humidity (RH) of the i n l e t and o u t l e t gas stream.
Days Number I n l e t RH% Out le t RH% Obs . M e a n Std D e v Mean Std Dev
1-21 1490 84 14 .0 ADL 36-42 488 69 3 . 3 88 2.5 43-54 590 67 7.8 88 4.4 79-97 858 69 5.9 85 4.6 98-111 661 68 9.8 83 7.0 126-139 607 63 5.7 85 5 . 7
(ADL = above de tec t ion l i m i t )
4 . 3 Moisture Content and pH of the Biofilter Media
Samples w e r e drawn from each s t age on days 20, 37, 51,
120 and 156 of opera t ion and the rnoisture con ten t and p H w e r e
determined. Table 4.4 con ta ins information on t h e rnoisture
conten t and p H of t h e b i o f i l t e r media during the study. 41
The moisture content of the three stages of the
biofilter ranged as follows: top stage from 40% - 53%; middle stage from 53% - 64%, and; bottom stage from 57% - 64%. The
top stage moisture content was often measured below the recommended operating range of 50% - 70%. This is l i k e l y
because the waste gas was not saturated with moisture prior
to entering the biofilter and the gas was stripping water
from the first stage. The moisture content in the middle and bottom stages were w i t h i n the recommended operating range.
The pH of the three stages of the biofilter ranged as
follows: top stage from 7.3 - 9.2; middle stage from 7 -5 - 8.7, and; bottom stage from 7.5 - 9.2. No buffering
materials were added to the bed, nor was any buffer solution
added to the bed through the irrigation system. The pH of
the biofilter media measured on days 37, 51 and 120 was
generally above the recommended range of 7 - 8. Except for one measurement, the pH of the biofilter media samples on day
156 were w i t h i n the recommended range. The biofilter bed was
irrigated with a nutrient solution of 100 g/L of KN03, on
days 128, 129, 133 and 134 of operation. The nutrient
solution may have provide some buffering capacity and reduced the pH in the bed.
4 . 4 Headloss of the B i o f i l t e r
The pressure &op across the biofilter was rneasured on
41 different days. The average pressure drop was 3.3 mm of water, with a standard deviation of 1 mm and a range of 2 to 6 mm of water.
Table 4.4: Moisture content and pH of the biofilter media.
D ~ Y Biofilter Stage Moisture Content PH (8 wet basis)
20 top stage middle stage bottom stage
26 top stage middle stage bottom stage
51 top stage middle stage bottom stage
120 top stage middle stage bottom stage
156 top stage top stage middle stage middle stage bottom stage bottom stage
156* top stage top stage middle stage middle stage bottom stage bottom stage
( * analysis performed by Analytical Services Laboratory, Land Resource Science, University of Guelph)
4 . 5 MEK and Toluene Removal
The removal rates of MEK and toluene during production
chemical loading was measured on 33 different days of
operation. Tables 4.5 and 4.6 show the operational
conditions and removal rates during these sampling periods.
Appendix C contains some typical sample data and a sample
calculation for removal efficiency and elimination capacity.
Figure 4.1 shows the MEK removal for the days sampled
during the study. The average removal of MEK during the
study was 733, with a standard deviation of 8% and a range of
59% to 87%. The elimination capacity for MEK during the
study was 17 g/m3/h, with a standard deviation of 7 g/m3/h
and a range of 6 to 46 g/m3/h.
Figure 4.2 shows the toluene removal for the days
sampled during the study. The average removal of toluene
during the study was 49%, with a standard deviation of 13%
and a range of 27% to 76%. The elimination capacity for
toluene during the study was 12 g/m3/h, with a standard
deviation of 8 and a range of 5 to 41 g/m3/h.
The removal efficiency of the biofilter for the mixture
of MEK and toluene was lower than removal efficiencies of
>90% typically reported in the literature, when MEK and
toluene were treated as single contaminants. However, those
studies involved labosatory scale biofilters which were
continuously exposed to either MEK or toluene. Weber and
Hartsman ( 1995 ) only achieved a 50% removal of toluene when
their compost-based biofilter was chemically loaded for 8
hours per day. The MEK removal was 59% on day 2 of operation
and was at 87% by day 7 of operation. While the toluene
removal was 56% on day 2 of operation and 76% on day 7 of operation. The acclimation period for the biofilter appears
to be no more than 7 days.
The MEK removal was always greater than the toluene
removal. This could be due to the fact MEK is more water
soluble than toluene, thus more would have been availabie in
the biofilm for the microorganisms to use as a food source.
The fluctuations in the removal of MEK and toluene appear to be synchronized.
Table 4.5: Operational conditions and MEK removal.
Day of Flow Velocity EBRT Inlet Outlet Rernoval Operat ion I m K I P E K I
( m 3 / h ) ( d h ) (SI (PPmv) (PPmv) ( % )
2 9.4 48.1 55 152 62 59 7 9.4 48.1 55 238 30 87 14 9-8 50.1 53 192 37 81 16 9.8 50.1 53 187 29 84 23 9.8 50.1 53 201 78 61 28 9.8 50.1 53 196 56 71 30 5.1 26.0 102 200 46 77 35 5-1 26.0 102 226 49 78 37 5.1 26.0 102 191 51 73 44 2.5 13.0 207 142 3 1 78 49 2.5 13.0 207 197 49 75 50 2.5 13.0 207 187 39 79 51 2.5 13-0 207 188 41 78 58 5-1 26.0 102 200 62 69 62 5.1 26.0 102 232 44 81 63 5.1 26.0 102 220 28 87 72 5.1 26.0 102 175 49 72 79 5.1 26-0 102 188 67 64 107 5.1 26.0 102 172 69 60 112 5.1 26.0 102 179 49 73 118 5.1 26.0 102 155 38 75 121 10-1 52.0 51 167 64 62 126 5.1 26.0 102 181 72 60 132 5.1 26.0 102 174 52 70 133 5.1 26.0 102 182 45 75 135 5.1 26.0 102 187 52 72 139 5.1 26.0 102 177 60 66 140 5.1 26.0 102 208 52 75 143 5.1 26.0 102 183 61 67 146 5.1 26.0 102 202 52 74 149 5.1 26.0 102 221 62 72 153 5.1 26.0 102 224 51 77 154 5-1 26.0 102 244 60 75
<-œ--,--------I.----C-----œ-œ.----I--œœœ-----.-------
Average 193 5 1 73 ~ t . Dev. 24 13 8 Minimum 142 28 59 Maximum 244 78 87
(EBRT=empty bed retention time)
Table 4.6: Operational conditions and toluene removal.
Day of Flow ~ e l o c i t y EBRT Inlet Outlet RemovaL Operation [Tol] [Toi]
( r n 3 / h ) ( m / h ) (SI ( P P W (PP~V) ( % )
-- -- -
(EBRT=empty bed r e t e n t i o n the ; T o l = toluene)
% Rem.
Figure 4.7: % Removal o f MEK
Day of Operation
% Rem.
Figure 4.2: O h Rernoval o f Toluene
Day of Operation
The removal r a t e s f o r both MEK and toluene appear to be
s l i g h t l y higher during October and Novernber, 1997 (first 6 1
days of operat ion) , when the chemical loading w a s t h e
g r e a t e s t . The average removal rate f o r MEK and to luene
dur ing t h i s period was 75% and 583, respectively.
The average removal rate for MEK and toluene, during
Decernber to March, when the chemical loading was
s i g n i f i c a n t l y less, was 71% and 42%, respectively.
On day 23 of operat ion t h e removal r a t e s appeared to
have taken a &op, with MEK a t 61% and t h e toluene a t 27%,
the lowest l eve l of to luene removal recorded. This drop may
have been caused by t h e flooding of t h e b i o f i l t e r on day 1 4
of operation.
4 . 6 Effect of Flow Rates on R e m o v a l
During t h e f i r s t 55 days of operation the f l o w rates
w e r e var ied from 2.5 t o 9.8 m3/h as described in T a b l e 4.2.
Table 4.7 l ists t h e average MEK and to luene removal under t h e
d i f f e r e n t flow rates. The removal of MEK and toluene ranged
from 74% - 78% and 51% - 65%, respec t ive ly , oves t h e range of
flow rates. It would appear t h a t removal e f f ic iency f o r both
MEK and toluene was no t s i g n i f i c a n t l y influenced when flow
rates w e r e var ied from 2.5 t o 9.8 m3/h.
Table 4.7: Average removal of MEK and toluene
under d i f f e r e n t flow rates.
D a y of Flow % MEK 8 Toluene Operation (m3/h) Rexnoved Removed
4 . 7 Removal of MEK and Toluene Through t h e Sections
of the Bed
The MEK and to luene concentra t ion i n t h e w a s t e gas
stream w a s rneasured a t each of t h e four plenums i n t h e
biof i l ter t o determine t h e amount of removal occu r r ing at
each s t age on days 50, 51, 1 1 2 , 126 and 139 of ope ra t i on .
During days 50 and 51 of opera t ion t h e flow was 2.5 m3/h.
For days 112, 126 and 139 of opera t ion t h e f low w a s 5.1 m3/h.
The results of the removal f o r MEK and to luene by stage are
listed i n Tables 4.8 and 4.9, r espec t ive ly .
On days 50 and 51, t h e t op s e c t i o n removed t h e m a j o r i t y
of t h e MEK with almost none being removed i n t h e bottorn
s ec t i on . However, on days 112, 126 and 139 al1 three s e c t i o n
w e r e removing MEK. The d i s t r i b u t i o n of the removal of MEK
appears t o have s h i f t e d over thne f r o m pr imar i ly the t o p
section t o a more even d i s t r i b u t i o n throughout t h e bed, The
to luene removal by s e c t i o n followed a similar p a t t e r n t o t h e
MEK removal. However on days 126 and 139, t h e t o l u e ~ e
removal i n t h e top s e c t i o n w a s i n s i g n i f i c a n t , with the lower
two sec t i ons removing the bulk of the to luene.
T a b l e 4.8: Percentage of MEK removed by each sect ion.
D a t e of Operation Top Middle Bottorn T o t a l Sec t ion Sect ion Sect ion R e m o v a l ( % ) ( % ) ( % ) ( % )
Table 4.9: Percentage of toluene removed by each sect ion.
Date of Operation Top Middle Bottom Total Section Section Section Removal ( % ) ( % ) ( % ) ( % )
4 .8 E f f e c t s of Periods of Non-use an8 Stagnation on Performance
During t h e study, t h e b i o f i l t e r was operated under t h e
production chemical loading condi t ions for approximately 672
hours o r about 18% of t h e t o t a l operat ional t h e . The
remainder of t h e tirne t h e b i o f i l t e r was operated under t h e
"no chemical loading" condi t ion when t h e dry laminator was
not runninq. The b i o f i l t e r was a l s o operated under t h e
"stagnant" condi t ion during days 144, 145, 151 and 152 of
operation. The e f f e c t of t h e s e two types of "non-use" w i l l
be discussed separately.
4 . 8 . 1 "No Chernical Loading" Condition
The b i o f i l t e r w a s operated i n t h e "no chemical loading"
condit ion f o r about 2928 hours o r about 79% of t h e t o t a l
operational t h e . The dry laminator t y p i c a l l y ran from 4 t o
16 hours per day from Monday t o Friday and was non-
operat ional on Saturday and Sunday. The b i o f i l t e r operated
i n the "no chemical loading" condi t ion for 63 days during the
study. T h e periods ranged from 1 to 11 days i n length.
Table 4-10 lists the number of thes t h e b i o f i l t e r was
operated for one o r more days under t h i s condition.
Table 4.10: Frequency of operating full days under the "No Chemical Loading" condition.
Number of Days Operated Under Fr equency "No Chemical Loading"
Data was typically collected at the begiming of each
week on Mondays or Tuesdays after the weekend shut-dom and
later in the week on Thursdays or Fridays . Table 4.11 shows
the removal rates for MER and toluene during six separate
weeks when sampling was conducted on Tuesday and Thursday or
Friday. These removal rates for MEK and toluene on Tuesday
compare favourably with the Thursday or Friday, within a
given week. This data would indicate that the typical 2 day
weekend shut-down of the dry laminator when the biofilter was
operated in the "no chemical loading" condition did not
appear to adversely affect the performance of the biofilter.
The biofilter was operated in the "no chernical loading"
condition from days 85 through 96 of operation, due to a
holiday shut-down. The removal efficiency of the biofilter
was not measured for 10 days after re-startup. The removal
efficiency of both MEK and toluene appeared to be re-
established at lower levels after the 11 day shut-dom Thexe was a sicpifkant difference between the average removal
efficiency of the biofilter before and after the 11 day shut-
down. The average removal of MEK and toluene prior to this
shut-dom period was 75% and 56%, respectively. The average
removal of MEK and toluene
69% and 40%, respectively.
mean MEK and toluene removal down. The means were found
after this shut-down period was
A t-test was used to compare the
rates before and after the shut- to be significantly different at
51
t h e 0 -5 leve l . The ca lcu la t ions f o r t h e t-test a r e located
i n Appendix D. The prolonged shut-down may have caused t h e
decrease i n t h e performance of the b i o f i l t e r , however it may
have a l so been due t o the dif ferences i n c h d c a l loading
before and a f t e r t h e shut-dom, o r a combination of t h e two.
The average hours of production chentical loading per day was
5 -2 pr io r to t h e shut-àown and only 3 -2 after t h e s h u t - d m .
The shut-down and decreased chemical loading may have
adversely a f fec ted t h e microbial population which was
degrading the MEK and toluene. The reduct ion i n removal
e f f ic iency a f t e r t h e shut-dom period may a l s o have been due
t o depletion of n u t r i e n t s , as no nut r ien ts w e r e added t o t h e
b i o f i l t e r u n t i l 3 1 days a f t e r t h e shut-dom.
4 . 8 . 2 "Stagnant '* Condition
To detemine t h e effect of operating t h e b i o f i l t e r i n t h e "stagnant" condi t ion during weekend shut-downs, t h e
b i o f i l t e r was operated i n t h i s condition for two 48 hour
periods (days 144, 145, 151 and 152 of opera t ion) on
subsequent weekends. T h e removal e f f i c i ency w a s measured on
Tuesday and Thursday a f t e r t h e weekend shut-downs. The
average removal f o r MEK and toluene a f t e r t h e shut-doms was
75% and 488, respec t ive ly . This compares favourably with
t h e study average removal for MEK and to luene of 75% and 49%,
respect ively . I t would appear t h a t operat ing t h e b i o f i l t e r
i n the "stagnant" condit ion during week-end shut-down periods
d i d not adversely e f f e c t t h e b i o f i l t e r ' s performance.
I n order t o demonstrate t h a t t h e removal of MEK and
toluene by t h e b i o f i l t e r was through b io log ica l oxidation,
the carbon dioxide levels i n t h e top and bottom plenum of t h e
Table 4-11: Removal rates for MEK and toluene on
different days of the same week-
Week D ~ Y MEK Toluene % Removal % Removal
Tuesday Thursday
Tuesday Thursday
Tuesday Thursday
Tuesday Thursday
Tuesday Thursday
Tuesday Friday
biof ilter were measured. The measurements were taken while
the dry laminator was operating and for several hours after
the dry laminator had been shut-dom. Carbon dioxide levels
were measured on days 58, 62, 63, 72 and 78 of operation.
Figure 4.3 shows the carbon dioxide levels on day 58 of
operation, which is representative of the other days. The
grouping of lower levels of carbon dioxide are from the top
plenum and represent the inlet gas carbon dioxide levels.
The grouping of higher levels of carbon dioxide are from the bottom plenum and represent the outlet gas carbon dioxide
levels. The dry laminator was shut-dom at approximately 245
minutes on the graph, at which point chemical loading was
stopped.
As shown in Figure 4.3, the carbon dioxide level was
more than 100 ppmv higher in the outlet air stream compared to the inlet air stream. Also, the level of carbon dioxide
in the outlet air stream dropped more than 50 ppmv, 390
minutes after the dry laminator was shut-down, when the
biofilter was no longer exposed to MEK and toluene. T h i s
profile indicates that aerobic biodegradation w a s responsible
for the removal of MEK and toluene.
Figure 4.3 Carbon Dioxide Levels on Day S8
Laminator Off Time (minutes)
4 . 1 0 Off-gassing Experiments
The off-gassing of MEK and toluene from the biofilter
bed was measured after chernical loading ceased w h e n the dry-
laminator w a s shut-off. The purpose of these experiments was
to determine the fate of the MEK and toluene in the w a s t e gas
Stream. T h e off-gassing experiments were conducted on days 58, 118 and 143 of operation. The concentration O£ MEK and
toluene in the biofilter inlet gas and outlet gas were
measured while the dry laminator was operating and after it
was shut-down, till no MEK or toluene were measured in the outlet gas. Note, the f l c r w to the biofilter remained
constant at 5.1 m3/h during these experhents. The off-
54
gassing p r o f i l e s f o r MEK and to luene w e r e used t o estimate
t h e m a s s balance as follows:
Difference = Q [MEK] i n l e t - (MEK removed + Q [MEK] o u t l e t + Q[MEK] off-gas)
Figures 4.4 and 4.5 show t h e off-gassing of MEK and to luene for day 58 of operation. These graphs are
r ep resen ta t ive of t h e off-gassing on days 118 and 143 of
operation. T h e zero on t h e x-axis of t h e graphs denotes
when t h e chemical loading ceased and t h e dry laminator was
shut-down. Data t o t h e l e f t of t h i s po in t show t h e
concentrations of MEK and to luene i n t h e i n l e t and o u t l e t gas
p r i o r t o shut-down. D a t a t o t h e r i g h t of t h i s p o i n t show t h e
concentrations of MEK and toluene i n t h e i n l e t and o u t l e t gas
a f t e r shut-down.
Figure 4.4 shows a rap id drop i n the concentration of
MEK and toluene i n t h e i n l e t gas a f t e r the dry laminator w a s
shut-down, reaching zero ppmv a f t e r 60 minutes. During t h e
clean-up operation a f t e r shut-dom, t h e process would s t i l l
be generating MEK and to luene f o r approximately 20-30
minutes. After t h i s no f u r t h e r chemical loading would occur.
Figure 4.5 shows an i n i t i a l rapid drop i n t h e concentration
of MEK and toluene i n t h e o u t l e t gas, followed by a gradua1
&op i n concentration, eventual ly reaching zero ppmv a f t e r
270 minutes. T h e n o n - c h d c a l l y loaded a i r would l i k e l y be
s t r i p p i n g t h e undegraded MEK and toluene from t h e biofilm.
The MEK and toluene l e v e l s i n t h e o u t l e t air would
e s s e n t i a l l y reach zero when al1 of t h i s MEK and to luene had
been s t r i p p e d f r o m t h e b i o f i l t e r bed.
Tables 4.12 and 4.13 l i s t t h e mass balance f o r MEK and
toluene respect ively, for days 58, 118 and 143 of operation.
The mass of MEK and to luene off-gassed from the bed on these
days ranged from 1.0 - 1.4 grams and 0.4 - 1.9 grams,
respectively. There w a s good agreement between t h e est imated
rnass of MEK and toluene loaded on t h e bed and t h e mass of MEK
and toluene removed by t h e bed thorough biodegradation,
ca r r i ed away i n t h e o u t l e t gas during operation and a f t e r
shut-dom. These s m a l l amounts of MEK and toluene being
s t r ipped from t h e bed a f t e r shut-down, coupled with t h e
carbon dioxide production during operation, i n d i c a t e t h a t t h e
removal was due t o biodegradation.
Table 4.12: Mass balance for MEK i n grams.
Day of Mass Mas s M a s s Mass Dif f erence Operation I n l e t Rernoved Outle t O f f -gas
Table 4.13: Mass balance f o r toluene i n grams.
Day of M a s s M a s s Mas s Mass Dif ference Operation I n l e t Rernoved Outle t O f f -gas
4.11 Nutrient Supplementation
Nitrogen is an e s s e n t i a l nu t r i en t f o r rnicrobial growth.
Nitrogen makes up about 15% of t h e dry ce11 weight and is a
major c o n s t i t u e n t of proteins and nucleic acids . The
majority of a v a i l a b l e ni t rogen i n nature i s i n an inorganic
f o m and most b a c t e r i a are capable of using ammonia o r
nitrate (Ray, 1995) . Other important macronutrients include
phosphorus, sulphur, potassium, rnagnesium, calcium, sodium
and i ron (Rayr 1995).Mature compost can be n u t r i e n t
de f i c i en t and n u t r i e n t s can be depleted oves t h e from
Conc. PPmv
Figure 4.4: Day 5 8 - MEK and Toluene lnlet
Concentration
Minutes After Shut-down
O MEK1 a TOLl
Figure 4.5: Day 5 8 - MEK and Toiuene Out le t Gas
Concentration
Conc. 90
PPmv
54 -- 45 -- 36 -- 27 -- 18 -- 9 "
O
O 1 I 1 I I 1 I .4 1 f 1 I I 1 I 1 1 I I v' 1 I 1 I
1 1
30 90 150 21 O 270
Minutes After Shut-down
compost-based biofilters, which can negatively impact the
removal efficiency of the biofilter. In order to investigate
the effect of nutrient (nitrogen) supplementation on the performance of the biof ilter, a concentrated solution of
potassium nitrate (KN03) was added to the bed through the
irrigation system. O n days 128, 129, 133 and 134 of
operation, the biofilter bed was irrigated with a 100 g/L
solution of KN03 and water. Laboratory grade KN03 from Fisher
Scientific and tap water were used to make the solution-
During this the period approximately 13.5 L of the solution
were added to the bed or approximately 1350 g of KN03. The
biofilter was operated at 5.1 m3/h during this period.
Ammonia was not chosen as the supplement because a 5%
solution of ammonia and water was used as the hardener to
solidify waste adhesive £rom the dry laminator. Use of a
mixture of ammonia and water in the biofilter irrigation
system may have caused the bed to become clogged with
hardened glue.
No samples of the filter media were taken for nutrient
analysis before the addition of the potassium nitrate
solution, as the air supply respiratory pump was
malfunctioning. Samples of the filter media were analyzed
for nutrient content at the end of the study. Also, samples
from the original batch of compost, which had been stored in
a sealed container at room temperature, were analyzed for
nutrient content. The nutrients analyzed were phosphorus,
potassium, magnesium, total nitrogen and biologically active
nitrogen (ammonium and nitrate). The results of the nutrient
analysis conducted on the filter media are listed in Table
4.14.
The original compost appears to have contained a
significantly higher concentration of NH4-N (armnonia) (932-
1001 mg/kg) compared to the media at the end of the study
(2.58-12-12 mg/kg). The original compost contained a
significantly lower concentration of NO3-N (nitrate) ( 0 . 7 0 -
1.51 rng/kg) compared to the media at the end of the study
( l49-lO9O mg/kg) . This increase in nitrate was likely due to the addition of the KN03 solution.
The MEK and toluene removal on day 133 of operation,
after the initial addition of the potassium nitrate solution,
waç 75% and 42%, respectively. The MEK and toluene removai
on day 135 of operation, after further addition of the
potassium nitrate solution, was 72% and 463, respectively.
The average removal rate for MEK and toluene for the last 60
days of operation after the solution was added was 71% and
44%, respectively. While the average removal rate for MEK
and toluene over the entire study was 73% and 49%,
respectively. The addition of the 100 g/L solution of KN03
did not appear to affect the removal efficiency of the
biofilter. This is contrary to what Morgenroth et al.
(1996) reported, when they reported that the addition of a
131 g/L solution of KN03 to a compost-based biofilter caused
a sustained increased removal efficiency of hexane f r o m 50%
to 99%. They concluded that nutrient (nitrogen)
availability may have limited the performance of the
biofilter-
The addition of the KN03 solution may not have enhanced
the biofilter's performance because:
i) biologically available nitrogen was not a limiting factor for the microbial population; or,
ii) b i o l o g i c a l l y available n i t r o g e n was a l i m i t i n g f a c t o r ,
however, t h e microbial p o p u l a t i o n may no t have been a b l e t o
u t i l i z e n i t r a t e as a n i t r o g e n source.
T a b l e 4.14: N u t r i e n t levels i n filter media from the o r i g i n a l compost and a t t h e end of the s tudy .
After Study Completed N u t r i e n t Original Top Middle Bot tom
~ o m p o s t stage Stage Stage
T o t a l P ( % ) Sample 1 0 . 48 Sample 2 O . 48
T o t a l K ( % ) Sample 1 0.81 Sample 2 1 - 1 7
T o t a l C a ( % ) Sample I 1.11 Sample 2 2 , 13
T o t a l M g ( % ) Sample I 0.50 Sample 2 0.47
N i t rogen
m4-N (mg/kg) Sample 1 1001 3 - 4 6 4.26 4 - 9 4 Sample 2 932 2 -58 7.85 12 1 2
N03-N (mg/kg) Sample 1 0 - 7 0 1090 385 . 5 468 -8 Sample 2 1.51 895.5 245.1 149.0
T o t a l N ( % ) Sample 1 1.28 0.74 0.48 O , 8 1 Sample 2 1.43 1.07 0.54 0 . 7 1
4 . 1 2 Microbial Profile
A l a r g e population of microorganisms capable of
deg rad ing t h e contaminants are n e c e s s a r y for s u c c e s s f u l
biofiltration. In order to support the hypothesis that
removal of MEK and toluene was due to biodegradation, a
microbial profile of the filter media was conducted at the
end of the study. Five samples from each of the three stages
were analyzed by the Microbial Laboratory, Laboratory
Services ~ivision of the University of Guelph to determine
the number of aerobic colony forming units per gram of media,
and the predominant types of microorganisms present. The
results of the microbial analysis are located in Table 4.15.
The number of aerobic colony forming units (cfu) per
gram of media ranged from 32 to 900 million. The 900 million
cfu/g appears to be an anomaly. When this data is removed,
the average aerobic cfu/g in the media was 52 million with a
standard deviation of 14 million. This is lower than the 1
billion cfu/g reported by Kiared et al. ( 1996 ) , however that study involved cornposted-based biofilters which were seeded
with bacteria. Further, these laboratory-scale biofilters
were continually exposed to contaminants which may have
helped to maintain a large microbial population. Lau et al. (1996) reported average total bacteria counts (tbc) of 27.6
million tbc/g, with a standard deviation of 56.9 million
t b c b in a full-scale compost-based biofilter operating at a
composting f acility . The results £rom this study compare
favourably with those reported by Lau et al. ( 1996) This
density of cfu indicates that there was a large population of
microorganisms present in the media. This fact further
supports the hypothesis that the removcrl of MEK and toluene
was through biodegradation.
The types of microorganisms found in large numbers
included the presence of at least eight types of non-lactose
fermenting Gram negative bacilli, including Proteus and Bacillus species. Gram positive bacteria, yeast and fungus were also present in moderate numbers.
Table 4.15: A e r o b i c colony forming units in the
filter media.
Sample A e r o b i c Colony Forming U n i t s (cfu) (million cfu/g)
TOD Section Sample 1 Sample 2 Sanple 3 Sample 4 Sample 5
Middle Section Sample Sample Sample Sample Sample
Bottom Section Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
4.13 Insect Profile
There were a large number of flying insects found in the biofilter throughout the study. The insects were found in the plenums of the biofilter and tubing of the manometer. The insects were identified by the Pest Diagnostic Clinic,
L a b o r a t o r y Services Division of the University of Guelph, as
being pomace f lies (Diptera Drosophilidae) . These insects
are know to lay their eggs in decaying organic m a t t e r . It is
believed flies hatched f rom the biof ilter media.
reported only as a point of interest, as insects closed biofilters was not found in any of the reviewed.
This is
living in
literature
5 . 0 Sources of Experimental Error
The ch ie f source of experimental e r r o r was t h e method
used t o determine t h e MEK and to luene l eve l s i n t h e waste gas
stream. Half ml gas samples w e r e drawn manually from t h e
b i o f i l t e r wi th a 1 m l gas t i g h t syr inge, f i t t e d with a gas
t i g h t valve. The samples were then manually injected i n t o
t h e gas chromatograph GC , equipped with f lame ioniz a t i o n
de tec tor (FID). This method is n o t a s reproducible as an
automated method. Var i ab i l i t y i n sample volume would effect
t he r e s u l t s from t h e GC. To reduce t h i s v a r i a b i l i t y al1
samples w e r e analyzed by t h e inves t iqa to r a f t e r p rac t i s ing
the method.
Cal ibra t ion curves fo r t h e GC w e r e prepared using
c e r t i f i e d gases a t t h e s t a r t of t h e experiment and
approximately half -way . The c e r t i f i e d gases introduced a
po ten t i a l e r r o r of +/- 2% t o 5%. I n order t o determine i f
t h e GC-FID column was operat ing cons i s t en t ly and n o t
d r i f t i n g , a sample £rom each c e r t i f i e d gas w a s run before and
a f t e r each set of b i o f i l t e r samples w e r e run. The GC-FID
w e r e considered operat ing cons i s t en t ly i f t h e s e samples w e r e
within +/- 10% of t h e c a l i b r a t i o n c u m e (recommendation by
the manufacturer of t h e GC). This value was based on t h e
recommendation of t h e suppl ie r of t h e GC-FID,
Canadian General Tower is concerned with lowering the
toluene emissions from their plant to ensure that toluene concentrations do not exceed the Ontario Ministry of
Environment and Energy ' s guidelines for ambient air quality . Mitigation of the dry laminator waste gas was considered a
priority as it is responsible for about 50% of the total
toluene emissions. MEK and toluene were successfully removed
from the coater hood stack's waste gas Stream using a
compost-based biofilter. Oves the 156 days of operation the
removal efficiencies for MEK and toluene averaged 73% and
49%, respectively. Biofiltration has the potential to
significantly lower the toluene emissions from the dry
laminator .
The carbon dioxide profiles of the biofilter outlet gas,
MEK and toluene biofilter mass balances and the presence of a
large microbial population in the biofilter media support
that biodegradation was responsible for the MEK and toluene
removal .
The biofilter acclimatized within 7 days of operation,
and removal efficiencies for MEK and toluene were not
affected when the flow rate varied £rom 2.5 to 9.8 m3/h. The
biofilter was only chemically loaded for about 18% of the
study period and experienced periods of no chemical loading
or non-use ranging from 1 to 11 days. The typical 2 day
weekend shut-down of the dry laminator, when the biofilter
was not chemically loaded, did not appear to adversely affect the performance of the biofilter. The Il day shut-dom may
have affected the performance of the biofilter. The average
removal of the MEK and toluene prior to this shut-dom was
75% and 56%, respectively. The average removal of MEK and
toluene after this shut-down was 69% and 40%, respectively.
This reduct ion i n removal e f f ic iency rnay a l s o have been due
t o t h e reduced chemical loading a f t e r t h e 11 day shut-down.
Operating t h e b i o f i l t e r i n t h e "s tagnant" condi t ion f o r 48
hours did n o t a f f e c t t h e performance of t h e b i o f i l t e r . The
biof i l t e r ' s a b i l i t y t o recover f r o m shut-downs and
disrupt ions appears t o be qui te good.
The add i t ion of nitrogen i n t h e form of a 100 g /L
so lu t ion of KNOî t o t h e filter media did not enhance the
performance of the b i o f i l t e r . Bio logica l iy a v a i l a b l e
nitrogen may not have been a l i m i t i n g f a c t o r i n the
performance of t h e b i o f i l t e r . Howevex , t h e microbial
population m a y not have been ab le t o u t i l i z e n i t r a t e as a
nitrogen source .
A compost-based b i o f i l t e r appears t o be a promising
means for t r e a t i n g t h e dry laminator waste gas. It
successful ly removed MEK and toluene f r o m the coater hood
w a s t e gas and t h e performance d id not appear t o be adversely
a f fec ted by shut-downs and disrupt ions . T h e study w a s
conducted on the w a s t e gas from t h e coater exhaust stack,
which has t h e lowest concentrations of MEK and toluene.
7 . 0 Recommendations
A study using a pilot-scale biofilter should be
performed on a mixture of waste gases from the four exhaust
stacks of the dry laminator. The mixture should be
representative of the volume which is exhausted from each
stack. This waste gas would have a higher concentration of
MEK and toluene than the coater hood waste gas used in the study. This study would provide a more definitive answer
regarding the feasibility of using biofiltration for treating
the dry laminator waste gas. This study was not conducted
because the dry laminator was being shut-down for an extended
period of t h e for modification.
Should f urther s t u d i e s be undertaken, removal
efficiencies for MEX and toluene could possibly be enhanced
through the following design and operation changes to the
biof ilter:
i) Humidification of the inlet air: The i n l e t air was not saturated with water prior to entering the
biofilter, and subsequently was lower than the
recomended levels. This resulted in stripping of water
Erom the biofilter bed.
ii) Addition of buffering agents to the f i l t e r media:
The pH of the biofilter media was frequently measured in
the range from 8 to 9 -2. This is above the recommended
pH range of 7 -8 and may have negatively ef fected the performance of the biofilter.
8 . 0 References
Bishop, W., Witherspoon, D., Card, T., Chang, D., and Corsi, R. (1990). Air emissions control technology assessment. Proc., Post-Workshop, Water Pollution Control Federation (WPCF) Res. Found., 7.1-7.9.
Chang, M., Voice, T.C. and Criddle, C.S. (1993). Kinetics of cornpetitive inhibition and cometabolism in the biodegradation of benzene, toluene, and p-xylene by tar pseudomonas isolates. Biotechnology and Bioengineering 41:1057-1065.
Corsi, R. L., and Seed, L.P. (1994). Biofilteration of BTEX- contaminated gas streams ; laboratory s tudies. Proceedings of the 87th Annual meeting of the Air Waste Management Association.
Desuhusses, M.A., Hammer, G., and Dunn, I.J.(1995). Behavior of biofilters for waste air biotreatment. 2. Experimental evaluation of a dynamic model. ~nvironmentai Science & Technology 29:1059-1068.
Desuhusses , M. A. , Hammer, G., and Dunn, I.J. (1996) . Transient-state behavior of a biofilter removing mixtures of vapors of MEK and MIBK from air. Biotechnology and Bioengineering 49:587-598.
Deshusses , M. A. , Transient behavior of biofilters : Start-up, carbon balances, and interactions between pollutants (1997). Journal of Environmental Engineering 123:563-568.
Ergas, S.J., Schroeder, E.D.,. Chang, P.Y. and Morton, R.L. (1995) . Control of volat~le organic emissions using a compost biofilter. Water Environment Research 67:816-821.
Gibson, M. J., (1995 ) . Biof iltration for compostirig odeur control: Labosatory studies using dimethyl disulphide. Master of Science Thesis, University of Guelph.
Hwang, J. and Tang, H. (1997). Kinetic behavior of toluene biofiltration process. Journal of the Air & Waste Management Associaition 47~664-673.
Howard, P.H., editor,(l990a) wdbook of ~nvironmentaï Fate and Exnosure - Dâta for Oroanic - Chemicals, Volume TI, Solvents. Lewis Publishers. Toluene, pp. 435-444.
Howard, P.H. (editor)(199Ob) Handbook of ~nvironmental Fate and Emosure Data for Oraanjc Chemicals, Volume I L Solvents . Lewis Publishers, Methyl ethyl ketone, pp. 334-340.
Kiared, K., Bibeau, L. Brzenzinski, G. V i e l , and M. Heitz. (1996) , Biological elhination of VOCs in biofilter. Environmental Progress 15:148-152.
Kirchner, K., Haukr G., and Rehm, H-J. (1987). Exhaust gas purification using immobilised monocultures (biocatalysts). Applied Microbiology and Biotechnology, 26:579-587.
Lau, A.K., B r u c e , M.P., and R.J. Chase. (1996). Evaluating the performance of biofilters for composting odor control. Journal Environmental Science Health A3(9):2247-2273,
Leçon, G. and Winer, A.M. (1991). Biofiltration: an innovative air pollution control technology for VûC emissions . Journal A i r Waste Management Association 41(8):1045-1054.
Liu, P.K.T., R.L. Gregg, R.K. Sabol and N, Barkley. (1994). Engineered biofilter for removing organic contaminants in air. Journal of Air & Waste Management Association 44:299- 303.
Mainville, D.M.(1996). Biofilteration of Odours: laboratory studies using butyric acid. Master of Science Thesis, University of Guelph.
Martin, F. Je and Loehr, F. (1996). Effect of periods of non- use on biofilter performance, Journal of Air & Waste Management Association 46:539-546.
Morgenroth, E., E.D. Schroeder, D.P.Y. Chang, and K.M. Scow. (1996). Nutrient limitation in a compost biofilter degrading hexane . Journal of Air & Waste Management Association 46~300-308.
Ottengraf, S ,P .P. and Van Den Oever, A.H .C. ( 1983). Kinetics of organic compound removal from waste gases with a biological filter. Biotechnology and Bioengineering 25:3089- 3102.
Ottengraf, S . P . P . , Meesters, J.J.P., Van Den Oever, A.H.C. and Rozema, H.R. ( 1996 ) . Biological elimination of volatile xenobiotic compounds in biofilters. Bioprocess Engineering 1: 61-69.
Pearson, C.C., ~ h i l l i p s , V.R., Green, G. and Scotford, LM. (1992) A minimum-cost biofilter for reducing aerial emissions Erom brioler chicken house. In: Dragt, A.% and H a m , J. van ( E d s ) . Bjotechnimes f o r a r Pollution Abatement and O d o u Contrai Pol3 cies . . , Proceedings of an International Symposium, Maastricht, The Netherlands, 27-29, October, 199 1 (pp 7 1-76} . Elsevier, Amsterdam.
Ray, B.T. (1995) Environmental Enaineerinq, PWS Publishing Company, Boston,
Robinson, K.G., Farmer, W.S. and Novak, J.T. (1990) Availability of sorbed toluene in soils for biodegradation by acclimated bacteria. Water Resources 24(3):345-350.
Seed, L.P. (1995). Biofiltration of VOCs: laboratory studies, Master of Science Thesis, University of Guelph.
Smith, F.L., G.A. ~orial, MIT. Suidan, A.W. Breen, P. Biswas, and R. C. Brenner. ( 1996 ) . DeveLopment of two biomass control strategies for extended stable operation of highly efficient biofilterç with high toluene loading. Environmental Science & Technology 30: 1744-1751-
Swanson, W.J. and Loehr, R.C. (1997) Biofiltration: Fundamentals, Design and Operations Principles, and Applications. Journal of Environmental Engineering 12 3 : 538- 546.
van Groenestijn, J.W., and Hesselink, G.M. (1993). Biotechniques for air pollution control. Biodegradation 4~283-301.
Weber, F. J. and Hartmans, S. (1995). Use of activated carbon as a buffer in biofilteration of waste gases with fluctuating concentrations of toluene. Applied MIcrobiology and Biotechnology 43:365-369.
Webster, T.S. and Devinny, J.S. (1996), Biofilration of odors, toxics and volatile organic compounds form publicly owned treatment works. Environmental Progress 15:141-147.
Weckhuysen, B., Vriens, L- and Verachter-t, H. (1993). The effect of nutrient supplementation on the biofilteration removal of butanal in contaminated air. Applied Microbiology and Biotechnology 39:395-399.
Yaddy, J.S. and Reddy, C.A. (1993) Degradation of benzene, toluene, ethylbenzene, and xylenes (BTEX) by lignin-degrading basidiomycete Phanerochaete chrysosporium. ~pplied and Environmental Microbiology 59:756-762.
Appendix A
Gas Chromatograph Cal ibra t ion Curve Data
Data f o r Cal ibrat ion Cumes: 20 ppmv
D a t e September 23, 1997
MEK=18.8 +/-0.9 pprn Tol=21.7 +Al. 1 ppm Graph
Graph
Average area STD
MEK FIT
2.583 2.583 2.583 2.583 2.583 2.566 2.583 2.600
Date January 6 , 1998
MEK=18.8 +/-0.9 ppm ToL21.7 +/-1.1 ppm Graph
Average area STD
MEK
Toi Area RT 182 4.950 169 4.966 184 4.950 172 4.950 172 4.933 173 4.933 163 4.966 175 4.966
MEK RT 2.6 2.6
2.6 16 2.6 16 2.61 6
2.6 2.6
Area 158 1 44 148 145 152 155 150
Area 378 389 435 399 391 41 1 309 390
Toi RT
4.983 4.966 5.000 5.000 5.000 4.9 66 4.983
Area 343
Data for Calibration Cumes: 200 ppmv
Date September 23, 1997
MEK=l8 1 4- 4 ppm Tol=184 +/- 4 pprn Graph
Average area STD
January 6 , 1998
MEK=18 1 +/- 4 ppm TOI= 1 84 +/- 4 ppm Graph
Average area STD
MEK RT
2.583 2.5 66 2.566 2.583 2.566 2.5 60 2.5 50 2.5 66 2.566 2.583 2.600
MEK RT
2.600 2.583 2.600 2.583 2.583 2.600 2.583
Area 1914 1932 1985 22'1 3 21 72 21 02 2116 1984 2049 1987 1938
Area 1831 1924 1874 1934 1910 1910 1945
Area 3732 3727 3854 4828 4574 4113 4052 4068 4209 3994 41 25
Area 391 5 4021 3896 4094 4078 41 47 4293
Data for Cal ibra t ion Cumes : 2000 ppmv
D a t e September 23, 1997
MEK=l823UO 4- 36 ppm TOI= 1 83 5 +/-37 ppm Graph
Average area STD
January 6, 1998
MEK=182300 +/- 36 ppm TOI-1 83 5 +/-37 pprn Graph
Average area STD
MEK RT
2.500 2.566 2.566 2.566 2.566 2.583
2.55 2.566 2.583 2.600
MEK RT
2.600 2.600 2.583 2.600 2.583 2.566 2.566
Area 21 61 6 20554 20975 21 261 21430 21154 21 245 18658 1 9061 20868
Area 19613 18499 19536 19856 18360 21118 21 252
Area 24004 22238 23094 23531 23193 24458 24062 22790 22937 22690
Area 24389 24339 24576 24955 23775 25689 25559
Calibration file: MEKI-CAL
Avg slope of curve: 10.70 Y-axis intercept: 0-00 Linearity: 0 . 9 3 Number of Levels: 3 SD/rel SD of CF's: 1-2/11 - 1 Y=<multi-lino r2: 1.0000
Lvl.Area/ht. Amount CF 1 174.000 18,800 9.255 2 2036.000 181 -000 I I -249 3 20682 .O00 1823 -000 1 1 - 3 4 5
Caiibration file: TOLI-CAL
O. O00 AMOUNT 1 NJ ECTED
Avg slope of curve: 17.49 Y-axis intercept: 0.00 Linearity: 0.76 Number of leveis: 3 SD/rel SD of CF's: 4 - 8 / 2 7 . 4 Y=<multi-lines r2: 1.0000
Cur ren t Previous C I Previous 174.000 O .O00 O. O00 2036-000 O .O00 O .O00 20682.000 O. 000 0 .O00
Current Previous # 1 Previous 388 .O00 0 .O00 O. 000 4116.000 0.000 O .O00 23300.000 0 .O00 o. O00
Calibration file: MEK12-CAL
hvg slope of curve: 9.89 Y-axis intercept: 0.00 Linearity: 0.91 Number of levels: 3 SD/rel SD of CF'S: 1.6/16-0 Y=<mul ti-lin@> r2: 1 .O000
AREA 1 3 :
s I # /
, / '-'
Lvl.Area/ht. Amount CF 1 150.000 18.800 7.979 2 1904.000 18L.000 10.519 3 19748.000 1823.000 10,833
! l
f 1
i i
i i i l I
1 I
Calibration file: TOL12.CAL
,
/ / * 1
l L/// i 1 i
2 I i
J
Current Previous SI Previous 150.000 0 .O00 O. 000 1904-000 0 -000 O. O00 19748 .O00 0.000 O. O00
O .O00 AMOUNT INJECTEO 1823.000
Avg slope of curve: 17.18 Y-axis intercept: 0.00 Linearity: 0.75 Number of levels: 3 SD/rel SD of CF'S: C.4/25.5 Y=<multi-line> r2: 1.0000
Lvl .Area/ht . Amount CF 1 350.000 21 -700 16.129 2 4063,000 184.000 22.082 3 24755.000 183s .O00 13 -490
Current Previous *1 Previous 350 -000 0 .O00 O. 000 4063.000 O -000 o. 000 24755 -000 O -000 O. 000
Appendix B
Sampling D a g Calibration Data
Daily Calibration Data: 20 ppmv Gas Standard
Graph
20c1 O 20C11 20c13 20c14 20C18 20C19 20C23 20C24 20C29 20C30 20C32 20C33 20C34 20C35 20C37 20C38 20C40 20C43 20C46 20C47 20C48 20C49 2ocso 2OC5 1 20CS3 20CS5 20C56 20C57 20C58 20C59 20C60 20C61 20C62
Average area STD Max Min
MEK Area 172 173 163 175 168 176 161 165 164 153 151 159 155 1 60 169 153 151 151 159 150 162 1 77 173 1 47 178 1 47 162 197 176 143 163 153 1 47
1 62 12
197 143
Area Date 387 2/10/97 411 2/10/97 309 7/10/97 390 7/10/97 340 14/10/97 377 14/10/97 393 16/10/97 333 16/10/97 415 23/10/97 340 23/10/97 402 28/10/97 305 28/10/97 332 30/10/97 41 5 30/10/97 459 4/11/97 455 4/11/97 358 6/11/97 347 13/11 /97 421 18/11/97 417 19/11/97 410 19/11/97 396 20/11/97 415 20/11/97 402 27/11 /97 398 27/11/97 349 1/12/97 347 1/12/97 429 2/12/97 421 2/12/97 335 1 1/12/97 382 11/12/97 378 18/12/97 417 18/12/97
RT= retention t h e , Tol=toluene
Daily Calibration Data: 20 ppmv Gas Standard
Graph
20C70 2OC7 1 20C72 20C73 20C74 20C75 20C77 2ûC78 20C80 20C8 1 20C82 20C83 20C85 20C86 20C87 20C88 20C89 20C90 20C9 1 20C92 20C93 20C96 20C99 20C1 O0 20C101 20C102 20C103 20C104
Average area STD Max Min
MEK RT 2.600 2.566 2.5 50 2.566 2.583 2.600 2.583 2.600 2.566 2.600 2.583 2.5 66 2.583 2.566 2.583 2.550 2.600 2.67 6 2.583 2.583 2.566 2.566 2.600 2.550 2.583 2.566 2.566 2.51 6
Area 155 1 63 147 153 1 47 150 151 174 126 128 157 194 178 162 152 172 147 157 158 157 152 158 135 140 139 147 159 163
154 15
194 126
Area Date 385 15/1/98 439 15/1/98 350 20/1/98 312 20/1/98 352 26/1/98 294 26/1/98 391 29/1/98 31 4 29/t /98 372 3/2/98 373 3/2/98 357 9/2/98 461 9/2/98 417 10/2/98 343 10/2/98 315 12/2/98 372 12/2/98 291 16/2/98 383 16/2/98 347 17/2/98 351 17/2/98 342 20/2/98 388 20/2/98 291 26/2/98 330 26/2/98 264 2/3/98 445 2/3/98 313 3/3/98 448 3/3/98
RT= retention t h e , Tol=tohene
Daily Calibration Data: 200 ppmv Gas Standard
Graph
200C13 200C14 200C15 200C16 200C17 200C18 200C19 200C23 200C24 200C25 200C28 200C29 2OOC3 1 200C32 2OOC3 3 200C34 200C35 200C36 200C37 200C38 200C39 200C40 200C42 200C43 200C44 200C45 200C46 200C47 200C48 200C50 200C5 1 200CS3 200C54 200C55 200C56 200CS7 200C58 200CS9
Average area STD Max Min
MEK RT 2-560 2.5 50 2.566 2.566 2.583 2.600 2.583 2.566 2.583 2.600 2.583 2.566 2.583 2.566 2.600 2.600 2.600 2.583 2.600 2.61 6 2.600 2.583 2.566 2.566 2.566 2.566 2.583 2.550 2.583 2.566 2.5 50 2.600 2.583 2.553 2,583 2.583 2.600 2.550
Area 21 02 2116 1984 2049 1987 1938 2059 1939 1898 1908 1909 1867 1958 1877 2054 2075 1786 2192 1915 2062 1919 2054 1972 2039 1929 1970 1975 1911 1917 1934 1969 7 843 1844 1889 1840 1850 1879 1869
1955 91
21 92 1786
Area Date 41 1 3 2/10/97 4052 2/10/97 4068 2/10/97 4209 2/10/97 3994 7/10/97 4125 7/10/97 4941 14/10/97 4461 14/10/97 4135 16/10/97 41 59 16/10/97 4244 23/10/97 4059 23/l OB7 4335 28/10/97 41 36 28/l O/97 4520 30/10/97 4517 30/10/97 3706 4/11/97 4605 4/11/97 4095 6/11/97 4463 6/11/97 4010 13/11/97 433 1 1 3/ 1 1 /97 441 7 18/11 /97 4296 18/11/97 4028 1 9/11 /97 4220 1 9/11 /97 4398 20/11/97 41 22 20/11/97 4080 27/11 /97 4026 27/11 /97 4286 1/12/97 4058 1 /12/97 3923 2/12/97 3898 2/12/97 3706 1 1 / l2 /97 3416 11/12/97 3668 18/12/97 3920 18/12/97
RT= retention the, Tol=toïuene
D a i l y Calibration Data: 200
Graph
200C67 200C69 200C70 200C77 200C72 200C74 200C75 200C76 200C77 200C79 200C80 200C83 200C84 200C8S 200C86 200C87 200C88 200C89 200C90 2OOC9 1 200C92 200C93 200C94 200C95 200C96 200C99 2ooc1 O0 200C1 O1 200C102 200C103 200C104
Average area STD Max Min
RT= retention the,
MEK Area 1845 1756 7 800 1800 1823 1921 1954 1 678 1908 1852 1946 1938 1934 1979 1867 1893 1836 1794 201 9 1925 1962 1788 1975 1838 1779 '1987 1994 1824 1802 1829 1809
1873 84
201 9 1678
ppmv Gas
TOI RT 5.000 4.933 4.983 4.9 3 3 5-01 6 4.983 4.983 S.000 4.983 5.000 5.000 5.01 6 4.983 4.950 5.01 6 4.983 4.9 66 4.9 66 4.9 3 3 4.983 4.983 4.983 4.966 4.9 66 4.966 4.950 4.950 4.950 4.966 4.983 4.950
Standard
Area Date 4248 15/1/98 401 2 1 5/1/98 3776 20/1/98 3910 20/1/98 4085 26/1/98 4268 26/7 /98 4461 26/1/98 3740 29/1/98 4249 29/1/98 4232 3/2/98 4266 3/2/98 4584 9/2/98 4597 9/2/98 4512 9/2/98 4135 10/2/98 4386 10/2/98 4063 12/2/98 3973 12/2/98 4413 12/2/98 4274 16/2/98 4276 16/2/98 4001 17/2/98 4394 17/2/98 4014 20/2/98 3727 20/2/98 4440 26/2/98 4464 26/2/98 4075 2/3/98 3942 2/3/98 3892 3/3/98 3842 3/3/98
Daily Calibration Data: 2000 ppmv Gas Standard
Graph
2000C6 2000C7 2000C9 2000C10 2000C1 1 2000C14 2000C1 5 2000C16 2000C17 2000C18 2000C21 2000c22 2000C24 2000C25 2000C26 2000C27 2000C28 2000C29 2000C30 2000C3 1 2000C32 2OOOC3 3 2000C34 2000C35 2000C36 2000C37 2000C38 2000C39 2000C41 2000C42 2000C43 2000C44 2000C45 2000C46 2000C47 2000C48 2000C49 2000C50 2OOOCS 1 2000CS2
Average area Sm Max Min
MEK RT 2.583
2.55 2 .S 66 2.583 2.600 2.583 2.566 2.566 2.566 2.550 2.600 2.600 2.600 2.600 2.583 2.600 2.583 2.600 2.633 2.600 2.600 2.600 2.583 2.583 2.566 2.583 2.5 66 2.5 3 3 2.566 2.566 2.566 2.533 2.61 6 2.600 2.583 2.550 2.566 2.586 2,583 2.583
A rea 21 154 21 245 18658 19061 20868 19676 2081 5 20500 19853 21 O89 18831 2089 1 19289 20742 21 041 21 728 18645 21 388 19596 2 1 844 19418 21 247 '18660 20981 19928 21651 21409 21 778 19245 21 334 22485 191 76 21 290 21 784 21 21 O 22223 18400 20794 18582 21 020
20488 1164
22485 18400
Area Date 24458 2/10/97 24062 2/ 1 0/97 22790 7/ l O/97 22937 7/ l O/97 22690 7/ l O/97 24013 14/10/97 23882 1 4/ 10/97 23512 74/10/97 23477 1 6/10/97 23851 16/10/97 23226 23/10/97 24337 2Wl O/97 23331 28/10/97 23662 28/10/97 24507 3O/ 1 0/97 24027 3O/ 1 0/97 23966 4/11 /97 24976 4/11 /97 24454 6/11 /97 25850 6/11 /97 24387 13/11/97 24794 13/11/97 25173 18/11/97 24278 1 8/ 1 1 /97 24942 1 9/11 /97 25437 19/11/97 25148 20/11/97 24795 20/11/97 23245 27/ l l /97 23952 27/71/97 25477 27/ 1 1 /97 24244 1 / 1 2/97 25871 1 /12/97 25612 1/12/97 25288 2/12/97 25845 2/12/97 24445 11/12/97 23671 11/12/97 24552 1 8/12/97 25368 l8/12/97
RT= retention the, Tol=toluene
Daily Calibrat ion D a t a : 2000
Graph
2000C61 2000C62 2000C63 2000C64 2000C65 2000C66 2000C67 2000C68 2000C69 2000C7 1 2000C72 2000C73 2000C74 2000C75 2000C76 2000C77 2000C78 2000C79 2000C80 ZOOOC8 1 2000C82 2000C83 2000C84 2000C85 2000C86 2000C87 2000C88
Average area STD Max Min
MEK RT 2.600 2.533 2.566 2.5 66 2.566 2.5 50 2.550 2.5 3 3 2.566 2.583 2.583 2.583 2.583 2.566 2.550 2.583 2.583 2.566 2.600 2.583 2.5 66 2.566 2.5 66 2.583 2.550 2.583 2.533
ppmv Gas Standard
Area 20540 16497 19966 18487 19135 18899 20564 17504 20806 19960 20685 207 14 20558 19707 19557 20805 19930 19200 20647 19653 21110 19946 21414 17824 21 738 19798 21 656
19900 1255
21 738 16497
Area Date 25398 1 5/1/98 22759 1 5/1/98 24702 20/1/98 23310 20/1/98 24600 26/1/98 24258 29/1/98 25329 29/1/98 24558 3/2/98 24875 3/2/98 24441 9/2/98 24605 9/2/98 25421 1 0/2/98 25737 1 O/2/98 251 90 1 2/2/98 24951 1 6/2/98 2431 4 1 6/2/98 24787 17/2/98 24444 20/2/98 24786 20/2/98 24857 23/2/98 25462 23/2/98 25632 26/2/98 26777 26/2/98 23228 2/3/98 25878 2/3/98 24460 3/3/98 25807 3/3/98
RT= retention time, Tol=toluene
Sample Calculation for R e m o v a l Efficiency and E l i m i n a t i o n Capacity
Typical Waste Gas Stream Data: Biofilter MEK and Toluene I n l e t and outlet
Concentration L e v e l s
B i o f i l t e r R e m o v a l Efficiencv
Concentration Concentration
Removal ( % ) =
entering b i o f i l t e r ( i n l e t ) = leaving b i o f i l t e r (outlet) =
238 ppmv 30 ppmv
Elimination Canacitv
El imina t ion Capacity
G = gas f low rate
G = 5.1 m3/h Biof i l t e r bed volume = 0.144 Biof i l t e r i n l e t concentration = 238ppmv = 0.70 g/m3 Biofilter o u t l e t concentration = 30 ppmv = 0.09 g/m3
Samples of the Typical D a t a Collect from the B i o f i l t e r
Oct 7/97 Sample Data
Graph
lnlet Conc. OCT7A 1 23 1 OCT7A2 258 OCT7A3 242 OCT7A4 21 9 OCT7A5 233 OCT7A6 242
AVE. 238
Outlet Conc. OC-nD 1 28 OCT7D2 34 0 m ~ 3 30 0 ~ ~ 7 ~ 4 30 OCnD5 29 OCT7D6 28
AVE. 30 % removal 87
Nov 13/97 Sample Data
Graph MEK1 ( P P ~ )
lnlet Conc. Novl3Al 139 Nov13A2 141 Nov13A3 139 Nov13A4 1 48 Nov13A5 142
AVE. 142
Outlet Conc. Novl3D1 30 NOVI 3D2 30 Nov13D3 . 34 Novl3D4 31 NOVI 3DS 30
AVE. 31 % removal 78
267 242 225 '189 194 207
221
66 64 51 48 48 45
54 76
TOLl ( P P ~ )
'1 33 7 23 I l 7 I l 7 '124
123
44 47 46 43 43
45 64
NOVI 9/97 Sample Data
Graph
lnlet Conc. Novl 9 A l Novl 9A2 NOVI 9A3
AVE.
Top Bed Outlet Conc. NOVI 961 NOVI 982 Nov1963
AVE, Oh Removal
Mid Bed Outlet Conc. Novl SC1 Nov19C2 Novf 9C3
Ave. % Removal
Outlet Conc. Novl9D1 Nov19D2 Nov19D3
Ave. % Removal
MEK 1 ( P P ~ )
193 183 184
187
53 59 58
57 70
60 58 59
59 68
38 40 40
39 79
Feb26/98 Sample Data
Graph
lnlet Conc. Feb26A1 Feb26A2 Feb26A3 Ave
Outlet Conc. Feb26D1 Feb26D2 Feb26D3
AVE. % removal
Appendix D
T - t e s t on the M e a n Removal Efficiencies for MEK and T o l u e n e Before and After
the Il-day Shut-down
T-test to Compare the mean Removal Eff ic iency for MEK and toluene before and after t h e Il-day shut-down
Bef ore 11 day shut dom Day of % R e m v a l Operation MEK
Statistical Tab le
Bef ore
A f t e r Il day shut down Day of % Removal Operat ion MEK
X2 3481 7569 6561 7056 3721 5041 5929 6084 5329 6084 5625 6241 6084 4761 6561 7569 Mean 5184 Sum 4096
102976
6 9
72487 T 0.05 = 2.042(1 for two-tailed test and 30 degrees of freedam
Toluene :
Bef ore 11 day shut dom D a y of % Removal Operation Tol
X 2 56 7 76 14 69 16 71 2 3 2 7 2 8 41 3 O 50 35 54 3 7 50 44 6 3 4 9 6 2 50 66 51 6 7 58 51 62 50 6 3 6 3 7 2 5 2 79 37
Mean 56 S m 1005
S t a t i s t i c a l Table
Bef ore N 18 Sum X 1005 *an 56
Sum x2 58841
A f t e r II day shut down Day of % RemovaL ûperation Tol
X2 X 3136 107 29 5776 112 4 8 4761 118 31 5041 121 30
729 126 2 9 1681 132 4 2 2500 13 3 3 9 2916 135 4 6 2500 139 3 4 3969 140 41 3844 143 4 0 4356 146 44 4489 149 51 2601 15 3 4 6 2500 15 4 4 9 3969 Mean 4 O 2704 Sum 599 1369
mer 15 variance~114
599 t= 4.28 40
24739 T 0.05 = 2.042 [3 for -tailed test and 30 degrees of Ereedom