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ECOTOXICOLOGICAL IMPACTS OF LANDFILL
LEACHATE AND ITS TREATMENT USING GREEN
COAGULANTSAGAMUTHU PARIATAMBY, KEE YANG LING, NURUL ASYIKIN BT AHAZAR
CENTER FOR RESE ARC H IN WAS TE MAN AGEMEN T
I N S T I T U TE O F B I O L O GI C AL S C I E N C E S , U N I V E R S I T Y O F M AL AYA, 5 0 6 0 3 , K U AL A L U M P U R , M ALAY S I A
What Is A Landfill?
Landfill ImpactsA large number of impacts may occur from landfill operations. These impacts can include:
Injuries to wildlife
Pollution of the local environment
Harbouring of disease vectors (such as rats/flies)
Methane is generated (by decaying organic wastes)
Fatal accidents (such as scavengers buried under waste piles)
Landfill Leachate During landfill site operation, a liquid known as leachate is produced. 3-4 million L/d in Malaysia.
It is a mixture of organic degradation products, liquid waste and rain water.
It has high organic carbon content and high concentrations of nitrogen
This liquid is highly toxic and can pollute the land, ground water and water ways
Landfill Toxins Many materials that end up as waste contain toxic substances.
Over time, these toxins leach into our soil and groundwater, and become environmental hazards for years.
Electronic waste is a good example.
Waste such as televisions, computers and other electronic appliances contain a long list of hazardous substances, including mercury, arsenic, cadmium, PVC, solvents, acids and lead.
Landfill Leachate Leachate contain compounds such as alkenes, ketones, esters, alcohols, polycyclic aromatic hydrocarbons (PAHs), phthalates, phenols, nitrogen compounds, carboxylic acids, amines, amides, aldehydes and carbohydrates (Dorian et al., 2013).
Persistent Organic Pollutants (POPs) are major concern in leachate due to their toxicity, persistence, long distance travel and bioaccumulation in animals.
More than 1000 chemicals were identified in contaminated groundwater at landfill site.
POPs are organic compounds that resist chemical, biological and photolytic degradation due to their inherent characteristics.
Categories of POPs The intentionally produced POPs include: - pesticides and industrial chemicals that may be traded between countries.
The unintentionally produced POPs which are by-products of industrial or other processes involving combustion which are not products in commerce.
Long range transportability
(Source: Tang, 2013)
POPs are organic compounds with long half-lives that can persist for a very longtime in the environment (Revathi and Jennifer, 2006).
More than 800 compounds appear likely to meet the criteria for the classification asPOPs (Brown and Wania, 2008).
At least 120 of these chemicals are produced in high volumes (1000 tonnes per year)(Brown and Wania, 2008).
Stockholm Convention on POPs came into force in 2004 and aim to protect humansand environment from POPs (Xu et al., 2013).
POPs listed in Stockholm Convention amendment (Xu et al., 2013)
2001 amendment 2009 amendment 2011 amendment
Aldrin Chlordecone (Kepone) Endosulfan
Endrin - HCH
Chlordane - HCH
HCB Tetra-BDE and penta-BDE
Mirex Hexa-BDE and hepta-BDE
Toxaphene PFOs and its salts
PCDDs and PCDFs
Chemical Structures of POPs
Chemical Structures of POPs
Aldrin Registration expired in 1994
Chlordane Registration expired in 1997
Dieldrin Registration expired in 1994
DDT Registration expired in 1999
Endrin Never registered
Hexachlorobenzene Never registered
Mirex Never registered
Toxaphene Never registered
Status of POPs in Malaysia
(Source: Consumers Association of Penang, 2005; Revathi and Jennifer, 2006)
Maximum concentration limit in Class IIA standard for pesticide levels in Malaysian river water suitable as water supply
Lindane 2 gl-1
Heptachlor 50 ngl-1
Endosulfan 10 gl-1
Total DDTs 100 ngl-1
Dieldrin 20 ngl-1
(Source: Leong et al., 2007)
Overview of POPs dispersion in the environment of air, water and biosphere
(Source: Langenbach, 2013)
Mechanism of POPs Degradation
Mechanism of POPs Degradation
Chemical stability: DDT degrades to DDE
DDE is less toxic than DDT but more resilient in the environment
Sources of POPsSources of POPs
Effects of POPs on wildlife/ humans
Dysfunctional immune, development and reproductive systems
Challenges in POPs ManagementOver the last decades, organochlorine pesticides were found extensively in used
About 253,989 kg of DDT had been applied as insecticide residual spray between
1991 to 1998 in Malaysia (Sani, 2007).
The total volume of leachate generated from landfills in Malaysia is estimated at
approximately 3.0 million liters per day (Agamuthu,2001).
In Malaysia, non-pesticide source of POPs are not well monitored (Roland et al.,
Methods such as coagulation, precipitation, and reverse osmosis have been
found to be limited for POPs removal (Rashed, 2013).
Challenges in POPs ManagementVery slow progress with the destruction of POPs pesticides and polychlorinated biphenyl (PCB) stockpiles
Exports of POPs in waste and products from industrial countries
Most remediation undertaken to date involves containment rather than the destruction or irreversible transformation
Leaves pollutants for future generations to manage and is not consistent with sustainable development
Continued use of POPs such as DDT can therefore be of lowest financial cost to the original consumer
Characteristics of Leachate Samples from Selected Landfills in Malaysia
JSL- Jeram Sanitary
PBSL- Pulau Burung
BTSL- Bukit Tagar
Leachate Treatment Methods
Aerobic Treatment Suspended Growth Systems
Activated Sludge Processes
Sequencing Batch Reactors
Attached Growth Systems
Moving Bed Biofilm Reactors
Anaerobic TreatmentSuspended Growth Systems Attached Growth Systems
Digesters (UASB, EGSB,DSF) Anaerobic Filter
Hybrid Bed Filter
Aluminum sulfate, Ferrous sulfate, Ferric chloride and Ferric chloro-sulfate are commonly used coagulants.
Effective for organic compounds and heavy metals.
Consistent sludge volume is produces
Increase in concentration of Aluminum or Iron, in the liquid phase, ,may be observed
High pH has to be maintained
Design and operating adsorption columns are easy
Availability materials which can be used as adsorbents(coconut shells, charcoal, zeolite, incinerator ash)
High removal efficiency of > 90% COD
Constant regeneration of activated carbon
Disposal of used carbon
Cost of GAC & PAC
Disadvantages in using Alum
Aluminium sulphate (alum) is a commonly used inorganic salt for treating wastewater.
Alum is chosen for treating POPs due to
- Low cost
- Easily available (Renault et al., 2009)
However, alum is not environmental friendly as it produces large amount of sludge and possible to be toxic.
The effectiveness of alum is highly dependent on pH and the flocs are not very mechanically resistant when formed in cold water (Renault et al., 2009).
What is Green Coagulant? Green coagulant is natural coagulant that is commonly used in water treatment due to its relatively cost-effective compared to chemical coagulants, can be easily processed in usable form and biodegradable.
Example of Green Coagulants Source
Guar gum Seed of the guar plant (Cyamopsis
Xanthan gum Strain of bacteria used during the
fermentation process, Xanthomonas
Locust bean gum Seed of the carob tree
Role of Green Technology
Natural coagulants are better options as compared to chemical coagulants in treating POPs due to
- Minimal coagulant dosage requirement
- Efficiency at low temperature
- Produce sma