LEACHATE MANAGEMENT AND TREATMENT Ahmed A.M. Abu Foul Environmental Department Islamic University of Gaza

Overview Leachate characteristics Impacts due to leachate Leachate sources Leachate collection Leachate treatment

Leachate Properties Leachate is liquid that percolates through the layers of the landfill and transports organic and inorganic compounds.

Typical Leachate BOD = 10,000 mg/l COD = 18,000 mg/l pH = 6 Total hardness = 3,500 mg/l Chloride (Cl) = 500+ mg/l Sulphate (SO4) = 300 mg/l Iron (Fe) = 60 mg/l

Factors Affecting Leachate Quality and Quantity Particle size Compaction Waste composition Site Hydrology Cover Design Waste age Landfill design/operation Sampling procedures Interaction of leachate with environment

Leachate Impacts Groundwater contamination Surface water pollution Odours Unsightliness

Leachate Generation Precipitation Surface water Run-on Water balance

Control of Liquids Run-off and run-on Precipitation Evapotration Water balance Water in waste

Water Balance

Monitoring and Mitigation Monitoring wells Collection and treatment Visual inspections Remediation

Leachate To Groundwater Most serious problem Expensive to correct Movement varies/hard to predict Depends on geology and soils

Groundwater and Leachate Migration

Leachate Collection System

Slotted Collection Pipes

Collection Pipe Above Liner

Leachate Management - Storage

Typical Collect and Treat

Leachate Treatment

Leachate Treatment Systems Recirculation Evaporation Biological treatment Natural Systems (Land application, Lagoons and wetlands) Conventional Systems (Activated Sludge, Sequencing Batch Reactor(SBR) Chemical treatments (Precipitation, Coagulation and Flocculation, oxidation) Physical treatments (Air Stripping, Filtration, Adsorption) Combination of Physical-chemical and biological treatments

Determine best alternative for treatment Designed on-site treatment system using current leachate data. Determined cost of treatment options. Compared on-site and off-site treatment.

FACTORS AFFECTING ON LEACHATE TREATMENT A- BOD/COD Ratio Relative biodegradability of leachate Present for as long as 100 years Tends to decline following onset of methane formation

Relative Biodegradability of Leachate BOD/COD COD/TOC Low < 0.5 < 2 Medium 0.5 – 0.75 2 – 3 High > 0.75 > 3

B- PH Influence chemical and biological processes of precipitation, redox, sorption, methanogenesis Controlled by volatile acids during acid phase After methanogenesis begins, controlled by carbonates and ammonia Major factor in controlling metal solubility

C- Effluent Limitations & Permitting Process Case-by-case basis based on: Type of receiving water body Aquatic life present in receiving water body Concentration of toxic chemicals based on pH, hardness, temperature, etc. Parameter Units Average Standard BOD5 mg/L 30 Total Suspended Solids NH3\N (May-October) 3 NH3\N (November-April) 6 Dissolved Oxygen 4 (minimum) PH S.U. 6.0-9.0

Example for Leachate Treatment Equalization Tanks Remove heavy metals and solids (optional) Remove biodegradable organics, ammonia, nitrite/nitrate, some heavy metals, and toxic compounds Air diffuser UV disinfection to remove pathogens Sludge wasting Lined reed bed for polishing treatment Discharge to local sewer system 2 SBRs with 24 hr cycle; 365000 gal. capacity NaOH to increase pH H3PO4 to bring pH down and add phosphate Air stripping tower to remove ammonia (optional) Na3PO4 to add phosphorous without changing pH

Sequencing Batch Reactor(SBR) A variation of the activated sludge process which incorporates equalization, aeration, and clarification.

Reed Bed Removal of heavy metals, BOD, TSS, Nitrogen, & Phosphorus

Heavy Metals Removal

Ultraviolet radiation (UV) Disinfection Removes pathogens Contact time only 5 seconds No disinfection by-products O&M Costs Low Simple Operation

Optional Components Chemical Addition Processes Phosphorus Addition Achieve optimum BOD:N:P ratio of 100:5:1 pH Adjustment Control pH levels to optimize performance Processes Metals Precipitation When metals concentration gets too high to meet effluent standards Ammonia Stripping When concentration of Ammonia is over 1000 mg/L