Study On Treatment Of Leachate By Integrated Biological And Physicochemical

Sanitary landfill is widely used in waste disposal over the world，about90.5%of the municiple wastein China is disposed through landfill. Methods of landfill leachate treatment include physical-chemicalmethod, biological method and earth disposal method, physical-chemical method and earth disposalmethod are usually used as pretreatment to remove or reduce restrictive factors for biochemical reactionand to adjust influent quality; biological method is usually used as secondary treatment.Base on the characteristics of landfill leachate, leachate recirculation （one earth disposal method） isused to reduce COD in leachate and Magnesium Ammonium Phosphate（MPA） method is used to reducedNH₃-N.Through the two pretreatment methods, the influent of biological process can be adjusted. In thispaper, the treatment effect of the two pretreatment methods is studied and the effluent effect of biologicalprocess.In this paper, studies of leachate recirculation in monomer garbage column shows that: under naturalconditions, the effect is obvious,after90days recirculation experiment, COD removal efficiency is54.3%,the ammonia removal efficiency is20.04%, and the TP removal efficiency is up to85.67%. The effect ofMAP for removing ammonia is improved with Mg²⁺and PO3-4increasing in chemicals added, when NH+4：Mg²⁺：PO₄^3-reduced from1:0.9:0.9to1:0.4:0.4,the effluent ammonia will rise from629.88mg/L to1062.79mg/L, the effluent phosphorous is reduced from675.97mg/L to75.53mg/L. The COD removalefficiency is not much effected by the adding ratio NH₄⁺：Mg²⁺：PO₄^3-.Leachate recirculation method can improve the water quality of leachate. After the system stablizing,the nutrient element C、N、P in recirculating leachate can meet the needs for subsequent biochemicaltreatment. SBR bioreactor operates stably with COD, ammonia and TP removal efficiency about71%,80%and80%without extra carbon source.When he adding ratio NH+²⁺3-4：Mg：PO4is controlled at1:0.4:0.4, the effect of MAP retreatment+SBR treatment is the best by adjusting C: N: P. With stable operation of system, the effluent CODefficiency, ammonia efficiency and TP removal efficiency from SBR reactor is about75%,90%and70%.