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Group Assignment 1 : Landfill Leachate Treatment
CHEMICAL ENGINEERING PROGRAMME
SEMESTER I (2011/2012)
KC 41503 ADVANCE ENVIRONMENTAL ENGINEERING
Group Members MATRIX NUM
ADELINE JELUNG BK08110232
BENJAMIN KAM BK08110127
CHEOH LIEW CHUAN BK08110093
DAVID SIAW WEN CHIIN BK08110031
EWAN TAMBAKAU @ WILLIAM BK08110189
FIRDAUS AZMEE BK08110175
LIOW KAI SING BK08110077
LOWEL CHONG BK08110131
SUSYANA SAMIRAN BK08110338
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Table of Contents
1.0 Introduction ........................................................................................................ 3
1.1 Leachate ......................................................................................................... 3
1.2 Leachate Quality .............................................................................................. 3
1.3 Impact of Leachate .......................................................................................... 3
1.4 Leachate Treatment ......................................................................................... 4
2.0 Landfill Selection ................................................................................................. 5
3.0 Leachate Type and Data ...................................................................................... 7
3.1 Kayu Madang Landfill Leachate Data ................................................................. 7
3.1.1 Analysis .................................................................................................... 7
3.2 Environmental Quality (Sewage) Regulations 2009 ............................................ 11
3.3 Available Water Treatment Technology ............................................................. 12
4.0 Process Selection ............................................................................................... 13
4.1 Process Description ......................................................................................... 13
5.0 Conceptual Design and Calculation ...................................................................... 14
6.0 Discussion ......................................................................................................... 17
7.0 References ........................................................................................................ 18
Appendix A Questions Asked During Presentation ......................................................... 20
Appendix B Discharge Limit Set by Department of Environment ..................................... 22
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1.0 Introduction
1.1 Leachate
Leachate is any liquid that, in passing through matter, extracts solutes, suspended solids or
any other component of the material through which it has passed. The precipitation that
falls into a landfill, coupled with any disposed liquid waste, results in the extraction of the
water-soluble compounds and particulate matter of the waste, and the subsequent
formation of leachate. Leachate produced from municipal solid waste landfill sites is
generally heavily contaminated and consist of complex wastewater that is very difficult to
deal with. Leachate produced form these waste dumping sites is heterogeneous and exhibits
huge temporal and seasonal variations.
1.2 Leachate Quality
The composition of leachate varies widely depend on waste type and the waste age
(Christensen et al., 1994). Leachate is characterized by high concentration of organic matter
(biodegradable and non-biodegradable), ammonia nitrogen, heavy metals, and chlorinated
organic and inorganic salts. Typically, the leachate can be characterized into three major
groups. The three major groups are mainly organic matters, inorganic matters and
xenobiotic organic compounds. Leachate pollution index (LPI) provides an overall pollution
potential of a landfill site.
Table 1.1 Pollutants in leachate (Aik H. L. et al., 2010)
Group of Pollutants In Leachate Components
Organic Matters Acids, alcohols, aldehydes and others such as Chemical
Oxygen Demand (COD), Biochemical Oxygen Demand
(BOD), Dissolved Organic Carbon (DOC), Volatile fatty
acis and refractory compound include fulvic-like and
humic like compounds
Inorganic Matters Sulfate, chloride, ammonium, calcium, magnesium,sodium, potassium, hydrogen carbonate, iron and
manganese and heavy metal like lead, nickel, copper,
cadmium, chromium and zinc
Xenobiotic organic compounds Aromatic hydrocarbon, phenols, chlorinated aliphatics,
pesticides and plasticizers include PCB, Dioxin, PAH, etc.
1.3 Impact of Leachate
A poorly designed landfill with no leachate collection system would face the consequences of
groundwater pollution. A release of leachate to the groundwater may present several risks
to human health and the environment. The release of hazardous and non-hazardous
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components of leachate may render an aquifer unusable for drinking-water purposes and
other uses. Leachate impacts to groundwater may also present a danger to the environment
and to aquatic species if the leachate-contaminated groundwater plume discharges to
wetlands or streams.
Once leachate is formed and is released to the groundwater environment, it will migrate
downward through the unsaturated zone until it eventually reaches the saturated zone.
Leachate then will follow the hydraulic gradient of the groundwater system and eventually
pollute the groundwater. It is therefore important to collect and treat the leachate formed in
the landfill.
1.4 Leachate Treatment
A number of ways may be applied to treat the leachate, these usually resulting in changes
of chemistry and a general reduction of strength from the original release. These treatment
are either physical (filtration, sorption, advection, and dispersion), chemical (oxidation-
reduction, precipitation-dissolution, adsorption, hydrolysis, and ion exchange), and biological
(microbial degradation).
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2.0 Landfill Selection
Overall there are more than 200 landfills in Malaysia serving the need of the city to remove
solid waste. Our group has chosen the landfill in Kayu Madang which is located in Kota
Kinabalu.
Location (GPS 6 o 06' 25.9" N; 116o 10' 29.1" E)
The site is located at Kg. Lapasan, Telipok within the Kota Kinabalu Industrial Park, 18 km
northeast of Kota Kinabalu City, see Figure 5.9. The waste disposal site covers an area of
8.9 hectares (22 acres).
History
Disposal of waste at this site started in 1997 and is expected to last until 2015. It has a
capacity of 15,333 cubic metres. The following picture shows the layout of the landfill.
Figure 1.1 Layout plan of Kayu Madang Landfill (Christianus, 2005)
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Waste collection coverage and amount of waste received
This site receives all types of waste except scheduled and hazardous waste from the rating
areas of Kota Kinabalu City, Penampang, Tuaran and Kota Belud. It receives an estimated
total of 9,000 tonnes of waste per month.
Site characteristics
The site is located in a gently sloping northeast-southwest trending valley with sloping hills
at the northeast and southwest. The valley floor is underlain by alluvium while sandstone
and shale underlie the hills. The surface runoff at the north western part of the valley flows
northwest into the Salut Bay. The immediate surrounding has not been developed and is
covered with secondary forest.
Design
Kayu Madang landfill is a Level IV sanitary landfill. It has a bottom liner but it is only in the
middle part; the liner comprises clay (1 m), sand (2 inches) and aggregate (5 inches). The
area is fenced with a gate and guard. Leachate is collected and pumped to the oxidation
pond. Groundwater wells have been installed. There is also weigh bridge and wheel wash.
Figure 1.2 Schematic diagram of Kayu Madang Landfill (Christianus, 2005)
Existing Leachate Treatment
It is to be noted that there is existing treatment for the leachate produced in the landfill.
The existing treatment plant, however, is inefficient in treating the leachate. The raw
leachate is pumped into a facultative pond before channeled into two maturation ponds.
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3.0 Leachate Type and Data
The selection of water treatment technology should be based on the type of influent
received by the water treatment facility. A water treatment facility for a palm oil mill might
be different from the water treatment facility for paper mill; this is true for landfill leachate
as well. By knowing the content of the effluent that needs to be treated, we can select
appropriate method that would best treat the effluent.
In this paper, we will evaluate the composition of leachate produced by Kayu
Madang landfill and select a suitable water treatment technology in comply with the
standard set by the Malaysian Government which can be referred in the Environmental
Quality (Sewage) Regulations 2009.
3.1 Kayu Madang Landfill Leachate Data
The selection of process presented in this paper will rely mostly on the data gathered from
journals and internet. Below is the leachate composition for the landfill site in Kayu Madang.
Table 3.1 physico-chemical of leachate in Kayu Madang (Christianus, 2005)
Parameter Range Average
BOD 22 208 mg/L 80 mg/L
COD 46 829 mg/L 313.4 mg/L
Suspended Solid 18 346 mg/L 121 mg/L
pH 6.61 7.61 7.184
Ammoniacal N 10.28 277 mg/L 168.256 mg/L
Nitrogen 35.18 296 mg/L 210.23 mg/L
Phosphate 0.5 mg/L 0.5 mg/L
Cadmium 0.01 mg/L 0.01 mg/L
Plumbum (Lead) 0.06 mg/L 0.06 mg/L
Chromium 0.05 mg/L 0.05 mg/L
Copper 0.03 mg/L 0.03 mg/LManganese 0.05 1.3 mg/L 0.49 mg/L
Nickel 0.04 mg/L 0.04 mg/L
Zinc 0.05 0.06 mg/L 0.055 mg/L
Iron 2.4 7.7 mg/L 4.67 mg/L
3.1.1 Analysis
The data in the table was acquired from the year 1997 to year 1999, with the landfill built
and began operation in 20 September 1997 (Christianus, 2005). The landfill is now 14 years
old, we expect some variation in the content of leachate as it age. Regrettably, the most
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recent data regarding the physico-chemical of the leachate is not available. In order to
select an appropriate water treatment process, we need to know the composition of the
leachate for the landfill. In this paper, we will attempt to compare the composition of Kayu
Madang Landfill Leachate with other data from other researches that are based in Malaysia
and other tropical countries.
As stated by Tchobanoglous et al. (1993) in his research, the composition of the
leachate will change as the landfill age. According to the data he collected, the magnitude of
pollutant in the leachate will depreciate overtime; this finding is in accordance with the
research done by Robinson & Luo (1991).
The selection of data will focus on the old landfill especially those in Malaysia and our
neighbouring countries and other tropical countries. The table below shows the place of
landfill, location, its corresponding age and the source of the data:
Table 3.2 Various Landfill in Malaysia and other tropical countries
Landfill Location Country Year Operated Reference
Pulau Burung Penang Malaysia 1991 Aziz H.A et al. (2003)
Kulim Penang Malaysia 1996 Aziz S.Q. et al. (2010)Nonthaburi Bangkok Thailand 1982 Theepharaksapan S. (2010)
Table 3.3 Comparison of values of leachate composition
Parameter Unit Pulau Burung Kulim Nonthaburi Kayu Madang
BOD mg/L 48 -105 135 476 400 22 208
COD mg/L 1533 2580 630 2860 2700 46 829
Suspended Solid mg/L 159 233 232 1374 290 18 346
pH - 7.5 9.4 6.93 8.26 8.44 6.61 7.61
Ammoniaca-N mg/L 360 730 130 1309 112 10.28 277
Nitrate-N mg/L 900 3200 400 2600 - 35.18 296
Phosphate mg/L 10 43 8.0 40 - 0.5
Cadmium mg/L - - 0.05 0.01
Plumbum (Lead) mg/L - - - 0.06
Chromium mg/L - - 0.17 0.05
Copper mg/L 4.60 - 0.50 0.03
Manganese mg/L 15.5 - - 0.05 1.3
Nickel mg/L - - 0.32 0.04
Zinc mg/L 0.10 0 1 - 0.05 0.06Iron mg/L 4.1 -19.5 0.6 11.4 2.95 2.4 7.7
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Both Tchobanoglous et al. (1993) and Kostova (2006) did a research and published their
findings regarding the variation of leachate composition over time. The findings can be
found in the table below:
Table 3.4 Concentration of some leachate characteristic at different phases (Kostova, 2006)
Leachate Transition
phase
Acid-formation
phase
Methane fermentation
phase
Final maturation
phase
Constituents (0 5 years) (5 10 years) (10 20 years) (> 20 years)
BOD 100 11000 1000 57000 100 3500 4 120
COD 500 22000 1500 71000 150 10000 30 900
TOC 100 3000 500 28000 50 2200 70 260
Ammonia 0 190 30 3000 6 430 6 430
NO2-N 0.1 500 0.1 20 0.1 1.5 0.5 0.6TDS 2500 - 14000 4000 - 55000 1100 - 6400 1460 4640
Table 3.5 leachate characteristic for new and mature landfills (Tchobanoglous et al., 1993)
Value, mg/L
New landfill (less than 2 years) Mature landfill
(greater than 10
years)Constituent Range Typical
BOD 2000 30000 10000 100 200
TOC 1500 20000 6000 80 160
COD 3000 60000 18000 100 500
Suspended Solid 200 2000 500 100 400
Organic Nitrogen 10 800 200 80 120
Ammonia nitrogen 10 800 200 20 40
Nitrate 5 40 25 5 10
Total Phosphorus 5 100 30 5 10
Ortho Phosphorus 4 80 20 4 8
Alkalinity (CaCO3) 1000 10000 3000 200 1000
pH (no units) 4.5 7.5 6 6.6 7.5
Calcium 200 3000 1000 100 400Magnesium 50 1500 250 50 200
Potassium 200 1000 300 20 400
Sodium 200 2500 500 100 200
Chloride 200 3000 500 100 400
Sulphate 50 1000 300 20 50
Total Iron 50 1200 60 20 200
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By looking at the tabulated data by both Tchobanoglous et al. (1993) and Kostova (2006),
we can make the following assumption:
1. BOD, TOC, COD, Suspended Solid reduce dramatically when the landfill is over 10years old.
2. The leachate becomes more alkaline over the time but not more than 7.5.3. Ammonia and nitrate content varies from time to time but is not significantly larger
than the first few years.
4. The metal content of leachate reduced by more than 50% after 10 years comparedto the first year.
Observing from the table, we noticed that there is a hike in concentration of composition of
leachate between year 5 and year 10. The concentration of the composition of leachate
declines steadily upon after 10 years. Since the leachate of Kayu Madang is more than 10
years. We have come up with the following values for the expected current leachate
composition by drawing values from other available leachate composition (Table 2.2) that is
within the scope of values is table 2.3 and table 2.4.
Table 3.6 Estimated physico-chemical of leachate in Kayu Madang in year 2011
Parameter Average
BOD 400 mg/L
COD 630 mg/L
Suspended Solid 159 mg/L
pH 8.3
Ammoniacal N 112 mg/L
Nitrogen 400 mg/L
Phosphate 10 mg/L
Cadmium 0.01 mg/L
Plumbum (Lead) 0.03 mg/L
Chromium 0.025 mg/LCopper 0.015 mg/L
Manganese 0.25 mg/L
Nickel 0.02 mg/L
Zinc 0.025 mg/L
Iron 2.30 mg/L
The data in the table above will be used in the analysis of the type of water treatment
process used in this paper.
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3.2 Environmental Quality (Sewage) Regulations 2009
In December 2009, the Department of Environment (D.O.E) Malaysia has revised the
Environmental Quality (Sewage) Regulation 2009. All the sewage discharge from the
domestic sewage treatment plant is typically subjected to the local, state and federal
regulations and standards. Under the regulation, the acceptable conditions for discharge of
leachate have been amended and can be referred in the appendix B.
The new standard of discharge limit with comparison to the projected composition of
leachate for the need for the treatment is summarized in the table below:
Table 3.7 Projected effluent and discharge limit with required action
Parameter Discharge Limit Projected Effluent Action required
BOD 20 mg/L 400 mg/L Yes
COD 400 mg/L 630 mg/L Yes
Suspended Solid 50 mg/L 159 mg/L Yes
pH 6.0 9.0 8.3 No
Ammoniacal N 5 mg/L 112 mg/L Yes
Nitrate N - 400 mg/L NoPhosphate -
10 mg/L No
Cadmium 0.01 mg/L 0.01 mg/L No
Lead (Pb) 0.10 mg/L 0.03 mg/L No
Chromium 0.20 mg/L 0.025 mg/L No
Copper 0.20 mg/L 0.015 mg/L No
Manganese 0.20 mg/L 0.15 mg/L No
Nickel 0.20 mg/L 0.02 mg/L No
Zinc 2.0 mg/L 0.025 mg/L No
Iron (Fe) 5.0 mg/L 2.30 mg/L No
In accordance with the law gazetted by the government, we come to a conclusion that only
BOD, COD, Suspended Solid and Ammoniacal Nitrogen need to be treated before it is being
discharged into the streams.
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3.3 Available Water Treatment Technology
Many leachate treatment methods have been proposed and can be found in the journal. The
table below is the summary of the processes and technology its effectiveness in treating
leachate.
Table 3.8 Comparison based on efficiency, installation and operation cost (Renou S. et
al., 2008; Madu J.I., 2008)
ProcessAverage Removal (%) Installation
& operationSkilled
personnelBOD COD TKN SS
Transfer
Recycling >90 60 80 - - Less No
Lagooning 80 40 95 >80 30 40 Less No
Physico/ChemicalCoagulation/flocculation - 40 - 60 80 Less No
Chemical precipitation - 80 60 90 >80 60 80 Less NoAnaerobic Processes >80 60 80 >80 60 80 Less NoPre-Anoxic Detrification >90 >90 >80 >75 Less NoMembrane Bioreactor >80 >85 >80 >99 Expensive No
Membrane FiltrationUltrafiltration - 50 60 80 >99 Expensive YesNanofiltration 80 60 80 60 80 >99 Expensive YesReverse Osmosis >90 >90 >90 >99 Expensive Yes
*Installation & operation cost and the need for skilled labour varies for Aerobic Process and
Anaerobic Processes. Biological aerated filter, Anaerobic filter are examples of processes
needing expensive installation & operation cost as well as skilled labour.
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4.0 Process Selection
A conventional activated sludge system will not be able to meet the new standard imposed
by the government as proven by Kutty S.R.M. et al. (2011). Thus, a more detailed process
with emphasis on the removal of nitrogen needs to be selected. In this case, our group has
chosen the Pre-Anoxic Detrification with activated sludge Process.
4.1 Process Description
The process of Pre-Anoxic Detrification with activated sludge can be best explained from the
diagram below:
Figure 4.1 Process flow of Pre-Anoxic Detrification with activated sludge (Gunasekara,
2011)
The Pre-Anoxic Detrification with activated sludge consists of an anoxic tank followed
by the aeration tank where nitrification occurs. Dissolved nitrogen in the form of ammonium
will be converted into nitrite ions and then to nitrate ions in the presence of oxygen by
nitrifying microorganism.
Nitrate produced in the aeration tank is recycled back to the anoxic tank where
denitrification will occur with the end product as Nitrogen. This overall process will not only
treat BOD, COD, Suspended Solid but also the ammoniacal-Nitrogen contained in the
leachate.
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5.0 Conceptual Design and Calculation
The core principle of the design was to have a complete mix activated sludge process
together with anoxic tank.
The leachate pumped up from the flow to the facultative pond first, then to the maturation
pond. After final maturation pond treatment, effluent discharge to the sea through Salut
river. The new system proposed (see Figure 5.1) is to further reduce BOD, COD to meet the
Environmental Quality (Sewage) Regulation 2009.
Figure 5.1: Proposed further treatment system
Existing plant effluent characteristic:
BOD5 = 400mg/L
Let,
Flow, Q= 0.150M3/s
Use Value of growth constants (source: Metcalf & Eddy, 2003 and Shahriari et al., 2006)
Ks = 100mg/L BOD5; m=2.5d-1; kd=0.050; Y=0.50mg VSS/mg BOD5 removed.
Assuming that the secondary clarifier can produce an effluent with only 30.0mg/L SS. We
can extimate the allowable soluble BOD5 in the effluent using the 63-percent assumption.
S = BOD5 allowed BOD5 in suspended solids
S = 30.0 (0.630)(30.0) = 7.4mg/L
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The volume of the aeration tank is then estimated using equation below:
The volume of the anoxic tank is estimated by setting the hydraulic retention time of the
tank roughly 25% of aeration tank as done by a group research team from Universiti
Teknologi PETRONAS in their pilot plant (Kutty S.R.M. et al, 2011)
) )
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6.0 Discussion
Many of the values in the table especially the current Kayu Madang landfill leachate might
not be accurate. The values are projected by referring from the other samples from other
landfills and the finding of journals. In order to get a better and more accurate data to
design a suitable waste water treatment facility, a most recent sample collection and
analysis is required.
There might be some slight variation in the calculation made as some of the
parameter constant (growth constant for microbes) are taken from journals and researches
from western countries. Very little research on the microbes activities in the tropical country
are observed and hence the limitation on the data during calculation.
While the landfill does not accept scheduled and hazardous waste which could
potentially lower the amount of metal in the leachate, the varying amount of BOD, COD and
TSS should be taken note of. Sabah has a very unique feature of unpredictable rainfall
which could potentially increase the amount of effluent, this could overload the water
treatment system. The equalizer installed at the head of the treatment plant should act as a
medium for concentration and flow equalizer.
The anoxic tank and anaerobic aeration tank could be combined for space efficiency,
such combination commonly dubbed as aeration/anoxic reactor. In this type of system, an
overall oxygen deficit condition is hard to be established across the entire contents of the
reactor and, unlike what is found with the reactors-in-series mode, there is no oxygen
uptake rate gradient to establish an initial oxygen deficit environment. Hence, this system is
generally not preferable.
Due to the stringent enforcement of the effluent limit set by the government, a
special treatment needed to be carried out. The Pre-Anoxic Detrification with activated
sludge process is one of the process modifications where non-conventional method is
applied. To maximize the denitrification performance in anoxic tank, oxygen delivery in the
anoxic tank should be 50% to 70% of the demand.
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7.0 References
Aik H. L., Hamid N. & Yung T. H. 2010. Influence of Waste Age on Landfill Leachate Quality.International Journal of Environmental Science and Development. 1(4): 258-264.
Aziz H.A., Yusoff M.S., Adlan M.N., Adnan N.H., and Alias S. 2003. Physico-Chemical
Removal of Iron From Semi0aerobic Landfill Leachate by Limestone Filter. WasteManagement. 24: 353-358.
Aziz S.Q., Aziz H.A., Yusoff M.S., Bashir M.J.K., and Umar M. 2010. LeachateCharacterization in Semi-aerobic and Anaerobic Sanitary Landfills: A Comparative Study.Journal of Environmental Management. 91: 2608-2614.
Barlaz, M., Baun, A., Christensen, T., Kjeldsen, P., Ledin, A. and, Rooker A.. 2002.Presentand Long-Term Composition of MSW Landfill Leachate : A Review. Critical Reviews inEnvironmental Science and Technology. 32(4): 364-371.
Chang, K.C., Chain. E.S.K., Dertien, J.T., Harper, S.R. & Pohland, F.G. 1985. Leachate
generation and control at landfill disposal sites. Water Pollution Resources Journal Canada.20(3): 10-24.
Christensen T.H., Kjeldsen P., Albrechtsen H.J., Heron G., Nielson P.H., Bjerg P.L., and HolmP.E. 1994. Attenuation of Landfill Leachate Pollutants in Aquifers. Critical Reviews inEnvironment Science and Technology. 24: 119-202.
Christianus P. 2005. Leachate Management in Kayu Madang Landfill, Telipok. Thesis.Universiti Teknologi Malaysia.
Gunasekara S.N. 2011. Improvements on Municipal Wastewater Treatment by: ChemicalPre-Precipitation with Ca2+ & Mg2+ and Acid Hydrolysis of Toilet Paper. Master Thesis. Royal
Insitute of Technology.
Ifeanyichukwu M.J. 2008. New Leachate Treatment Methods. Master Thesis. Lund University.
Kostova I. 2006. Leachate from Sanitary Landfills-Origin, Characteristics, Treatment.Borovetz: University of Architecture, Civil Engineering and Geodesy.
Kutty S.R.M., Isa M.H., Leong L.C. 2011. Removal of Ammonia-Nitrogen (NH3-N) and Nitrate(NO3
-) by Modified Conventional Activated-Sludge System to Meet New D.O.E Regulations.Perak: Universiti Teknologi PETRONAS.
Laugesen C.H., Lim P.S. & Mohd Iskandar M.A. Solid waste disposal in Sabah. Environmental
Conservation Department, Sabah Survey Report August 2002.
Regulations 2009. Environmental Quality (Control of Pollution From Solid Waste TransferStation and Landfill) Regulations 2009 (Regulation 13). Kuala Lumpur: International LawBook Service.
Renou S., Givaudan J.G., Poulain S., Dirassouyan F., Moulin P. 2007. Landfill LeachateTreatment: Review and Opportunity. Journal of Hazardous Materials. 150: 468-493.
Robinson H. and Luo M. 1991. Characterisation and Treatment of Leachates From HongKong Landfill Site. Journal of the Institution of Water and Environmental Management. 5(6):326-335.
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Shahriari H., Eskicioglu C. and Droste R. L. 2006. Simulating Activated Sludge Systems bySimple-to-Advanced Models. Journal of Environmental Engineering. ASCE 132(1): 42-50.
Tchobanoglous G., Theisen H., and Vigil S. 1993. Integrated Solid Waste ManagementEngineering Principles and Management Issues. Singapore: McGraw-Hill, Inc.
Theepharaksapan S., Chiemchaisri C., Chiemchaisri W., and Yamamoto K. 2011. Removal ofPollutants and Reduction of Bio-toxicity in a Full Scale Chemical Coagulation and ReverseOsmosis Leachate Treatment System. Bioresource Technology. 102: 5381-5388.
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Appendix A Questions and Answer During Presentation
1. What is the capacity of the landfill?A: The Kayu Madang landfill have a capacity of 15,333 cubic metres.
2. Please cite the reference for the schematic diagram of landfill.A: Christianus P. 2005. Leachate Management in Kayu Madang Landfill, Telipok. Thesis.
Universiti Teknologi Malaysia.
3. Why you did not choose tropical work and data (calculation part)?A: Very little research on the microbes activities in the tropical country are observed and
hence the limitation on the data during calculation.
4. For the process proposed in UTP thesis (Kutty S.R.M. et al.), criticize the method.Nothing is perfect.
A: They uses a pilot plant where the leachate is made up of lab chemicals and not real
leachate, hence the possibility of inaccuracy. In the process, steady state flow were used for
the pilot plant, real life situation may differ from the pilot plant. The calculation for tank size
were BOD based and not Ammoniacal-Nitrogen. It is optimized for BOD and not
Ammoniacal-Nitrogen.
5. How do you achieve constant flow?A: By using equalizer tank, we can achieve constant flow
6. How do you measure the flow rate of leachate?A: Any flow measuring device such as rotameter can be used to measure the flow.
7. Where the waste comes from?A: This site receives all types of waste except scheduled and hazardous waste from the
rating areas of Kota Kinabalu City, Penampang, Tuaran and Kota Belud.
8. How do you maximize the performance of denitrification? What is the parameterinvolved?
A: Nitrification largely depended on the food/mass ratio and the deficiency of oxygen in the
liquid. The retention time also affect the performance. By increase the food/mass ratio,
adjusting the oxygen of 50-70% of the demand and lengthen the rentention time.
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9. Why use anoxic tank instead of other tank? Think of a simultaneous treatment withanoxic and anaerobic.
A: Anoxic tank is used for its denitrification process which is good in eliminating the
ammoniacal-nitrate. The anoxic tank and anaerobic aeration tank could be combined for
space efficiency, such combination commonly dubbed as aeration/anoxic reactor. In this
type of system, an overall oxygen deficit condition is hard to be established across the entire
contents of the reactor and, unlike what is found with the reactors-in-series mode, there is
no oxygen uptake rate gradient to establish an initial oxygen deficit environment. Hence,
this system is generally not preferable.
10.How much sludge come out? How do you measure?A: The amount of sludge coming out has yet to be ascertain as not enough data is available
for calculation at the moment. Sludge can be treated as viscous liquid and can be measure
same as liquid.
11.If during heavy rainfall, how do you prevent it from overflow?A: Equalizer would be able to contain the rainfall and adjust the flowrate to prevent overflow
of the tank.
12.How to maximize performance of nitrification, is the aeration control important, how doyou control it?
A: Similar to question number 8.
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Appendix B Discharge Limit Set by Department of Environment