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Similar to WWQM CH-8 Treatment and disposal of leachates from landfills.pptx
WWQM CH-8 Treatment and disposal of leachates from landfills.pptx
- 1. CHAPTER EIGHT Treatment and disposalof leachates from landfills A landfill is a site for the disposal of waste materials. It is a designated site for the disposal of waste by burying it in the ground. Leachate is the liquid that percolates through landfill waste, often carrying dissolved and suspended pollutants. It is Water that has percolated through a solid and leeached out some the constituents. Landfill leachate is produced by residual water and precipitation passing through degrading waste deposits
- 8. Landfill leachates mayconstitute
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- 19. Leachate Properties AffectingTreatment Contaminant Concentration Fluctuation Some peak quickly and decline: e.g., BOD Some persist for long periods: e.g., NH3-N Daily and seasonal variations occur
- 20. Planning Treatment andDisposal Estimate leachate flow, Q ➹ Variations with site age Estimate leachate contaminant conc., C ➹ Type ➹ Variations with age Identify treatment and disposal options with discharge standards and cost Select treatment and disposal system ➹ Introduce uncertainty ➹ Maintain flexibility Q t C t
- 21. Constructed Wetland 7 Uses Polishingtreatment Complete treatment Advantages Relatively inexpensive to build/operate Associated with ‘green’ technologies Wetlands credits Disadvantages Large land requirement Cold weather Mediocre results especially for complete treatment systems
- 22. Reed Bed forEffluent Polishing 88
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- 24. Leachate Treatment 24 Off-Site ➹Removalby road tanker to sewage works ➹Removal via pipeline or sewer to disposal site ➹Most common On-Site ➹Biological ➹Physical/Chemical ➹Mixed
- 25. On-Site Treatment 25 Physical/ChemicalProcesses ➹ Coagulation/flocculation/settlement ➹ pH control and aeration/air stripping ➹ Activated carbon adsorption ➹ Reverse osmosis ➹ Oxidation with hydrogen peroxide ➹ Oxidation with hypochlorite ➹ Degassing ➹ Evaporation Biological ➹ Aerobic: trickling filter, activated sludge, aerated lagoon, rotating biological contactor, sequencing batch reactor (SBR) ➹ Anaerobic: submerged filter, upflow anaerobic sludge blanket (UASB) ➹ Anoxic: denitrification Mixed ➹ Land treatment ➹ Vegetated ditch/root zone treatment
- 26. Suspended growthsystem Completely mixed mode; batch mode with discontinuous flow Influent 2 3 1 Fill React Settle Effluent 4 Draw Idle 5 Mixing Sequencing Batch Reactor (SBR) 26
- 27. Aerated Lagoons Surface aerator Raw wastewater Effluent Suspendedgrowth system Comletely mixed mode Contact time limited to hydraulic retention time due to no recycle of sludge Limited effluent quality 27
- 28. Rotating Biological Contactor(RBC) Attached growth system Design based on specific surface area Aeration provided by rotating disks Better performance than other fixed- film systems due to lower organic loading per mass of biomass, longer detention time, and little short- circuiting 28
- 29. Anaerobic Fixed FilmReactor Sludge age: > 100 days VSS: > 20,000 mg/L Increased efficiency and rapid elution of toxic sludge Not good for wastes containing a large portion of particulates and/or carbohydrates due to clogging Possible to treat low strength waste at nominal temperatures economically Effluent recycle (sufficient alkalinity) to raise pH to 7 Possible buildup of nonbiodegradable solids in reactor Loading rate: 0.42~3.4 kg COD/m3·day at 25°C; 60~80% COD 29
- 30. Upflow Anaerobic Sludge Blanket(UASB) Reactor High sludge age at high loadings with separation of gas from the sludge solids VSS: 20,000 ~ 150,000 mg/L Sugar-beet waste: reactor size 800 m3, loading 10 kg COD/m3·day, and HRT 4 hrs treatment efficiency 80% Difficult to maintain low effluent SS levels and occasional unexplained biomass washout 30
- 31. On-Site Treatment 31 Anaerobic BiologicalTreatment Anaerobic Fixed Film Reactors (AFFR) Films better than digesters ➹ Biomass washout reduced ➹ Higher loading possible ➹ Kinetically better Experience ➹ Field – limited ➹ Laboratory: support medium - granular carbon, plastic film, sand,
- 32. On-Site Treatment 32 Physical/Chemical Processes Addition of simple chemicals followed by a sequence of mixing, coagulation/flocculation, and settlement Chemicals tested: ➹ Hydrated lime ➹ Quick lime ➹ Sodium hydroxide ➹ Magnesium hydroxide ➹ Alum ➹ Ferric chloride ➹ Ferric sulfate ➹ Polymeric coagulant aids
- 33. On-Site Treatment Physical/Chemical Processes- Examples Influent Lime Sludge Backwash Effluent Carbon Adsorption Granular Filtration Sedimentation Chemical Precipitation Precipitate metals Settle precipitates Clarify influent to carbon adsorption Carbon regeneration Adsorb TOC and solvents Destroy TOC and solvents 33
- 34. Proposed Leachate Treatment Chemical Sludge wasting Remove ammonia (optional) Removeorganics, ammonia, nitrite/nitrate, and toxic compounds Polish the effluent Reed bed Discharge Leachate Equalization Tank Chemical Precipitation Chemical Equalize flow Remove heavy metals and solids 34 (optional) Air Stripping SBR
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- 36. Landfill as aBioreactor 36 Measure of Success Faster landfill stabilization Increased air space Reduced leachate management costs Reduced gases and odors Reduced long-term care costs Possibly, mining to regenerate cover material - a perpetual landfill?
- 37. Leachate Recirculation 37 Canbe used during the early stages when leachate production quantities are low. Can be used in later stages to eliminate problems of off-site transport during peak production periods or during downtimes of the transport devices. Advantages Attenuation of leachate strength/quantity Increased rate of landfill stabilization Enhanced gas production rates Immobilization of metals from landfill material Improved landfill settling rates Increased compaction rates
- 38. Disadvantages Ponding/localized accumulationof leachate Severe localized subsidence/side slope stability problems Other management requirement due to excess leachate production Selective attenuation of contaminants recirculation, thus further treatment required Mass/fluid transfer limitation 38 Leachate Recirculation
- 39. Methods of Recirculation Spray irrigation Surface application Gravity well/trench Injection well/trench Infiltration ponds 39 Leachate Recirculation (3)
- 40. Spray Irrigation 40 Advantages Goodcoverage Moderate weather restrictions Subject to evapotranspiration Easily adjusted for settlement concerns Disadvantages Subject to plugging Sophisticated design and construction Subject to freezing Surface water contamination potential
- 41. Injection Needles 33 Advantages Portable Good coverage Moderate design, construction requirements Moderate weather restrictions Easily adjusted and maintained Disadvantages Potential crushing of pipes Subject to freezing Surface water contamination potential (thru pipe leaks), limited use after capping
- 42. Surface Application 42 Advantages Simpledesign Most evaporation potential Good coverage Low capital investment Least subject to plugging Easily accessed for maintenance Disadvantages Odor Weather restrictions (wind, rain) Health risk Surface water contamination risk
- 43. Vertical Wells 43 Advantages Minimalweather restrictions No odor Simple design Easily combined with horizontal distribution lines Disadvantages Poor coverage w/o horizontal distribution Susceptible to differential settlement damage Subject to plugging Subject to short circulating of leachate Difficult to maintain vertical levelness
- 44. Horizontal Wells/Trenches 44 Advantages Fairto good coverage Minimal weather restrictions Disadvantages More sophisticated design and construction required Susceptible to differential settlement damage Virtually impossible repair or maintenance
- 45. Management of Leachate Collection(Drainage layers, Pipes and Storage tanks) Treatment(Pre-Treatment, Biological Treatment and Advanced Treatment) Disposal(Discharge to Municipal Sewers, Recirculation, Evaporation and Off-site Treatment)