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LEACHATE MANAGEMENT AND TREATMENT

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.

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LEACHATE MANAGEMENT AND TREATMENT

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

  2. Overview • Leachate characteristics • Impacts due to leachate • Leachate sources • Leachate collection • Leachate treatment

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

  4. 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

  5. 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

  6. Leachate Impacts • Groundwater contamination • Surface water pollution • Odours • Unsightliness

  7. Leachate Generation • Precipitation • Surface water • Run-on • Water balance

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

  9. Water Balance

  10. Monitoring and Mitigation • Monitoring wells • Collection and treatment • Visual inspections • Remediation

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

  12. Groundwater and Leachate Migration

  13. Leachate Collection System

  14. Slotted Collection Pipes

  15. Collection Pipe Above Liner

  16. Leachate Management - Storage

  17. Typical Collect and Treat

  18. Leachate Treatment

  19. 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

  20. 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.

  21. 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

  22. Bio-degradability BOD/COD COD/TOC Low < 0.5 < 2 Medium 0.5 – 0.75 2 – 3 High > 0.75 > 3 Relative Biodegradability of Leachate

  23. 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

  24. Parameter Units Average Standard BOD5 mg/L 30 Total Suspended Solids mg/L 30 NH3\N (May-October) mg/L 3 NH3\N (November-April) mg/L 6 Dissolved Oxygen mg/L 4 (minimum) PH S.U. 6.0-9.0 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.

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

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

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

  28. Heavy Metals Removal

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

  30. Optional Components Chemical Addition • 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

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