Research On The Recirculation Of Leachate From Municipal Refuse Landfill

At present, almost 90% of the municipal refuse in our country was treated with the technology of landfill. The principal environmental problem of landfill is leachate of which the water quality is complex, with high COD_Cr and high heavy metal ion concentration as well as high NH3-N concentration. The soil and groundwater will be polluted if the leachate entering into environment.Under the completely natural condition, The paper adopts the pattern which landfilling, collects the leachate and studies the leachate recirculation method processing effect.The recirculation experiment is mainly anaerobic recirculation, according to the research goal and the content, the experiment divides into three phases. The first phase mainly studies the quality of leachate change situation as well as the subsidence of speed rate change of landfilling body in the initial landfilling period. The second phase main studies the influence form leachate recirculation to landfill body stabilizing advancement. The third phase main studies the influence form different hydraulic load to the recirculation processing craft effect.Through above three phases experimental study, draws following main conclusion:(1) In landfilling initial 30 days, the leachate CODcr, NH₃-N content achieves the maximum accumulation in the 20th day.(2) In temperature range which carries on in the experiment, landfill body average subsidence speed (y) is linear correlation to the total time of landfill body (x), its relationship is:y = -0.0203x+1.225 correlation coefficient R2 = 0.9917, linear relevance well.(3) Owing to recirculation, time of the anaerobic metabolism phases can be reduced, and also, decomposition of the organic substance can be accelerated. Thus, finally stabilization of the refuse is speed up.(4) When Hydraulic load is about 5.02mL/L·d, the organic load is 76.3 mL/L·d ,it may achieve best CODcr disposal effect, the disposal rate is 48.46%.(5) Changing hydraulic load is not obviously to the NH₃-N disposal. Comparatively, the leachate recirculation is best to the NH₃-N disposal effect, disposal rate reaches to the maximum 37.2%.(6) Hydraulic load oversized is not advantageous to SS disposal. When the hydraulic load is 4.24 mL/L·d, SS disposal rate reaches to the maximum 39.19%.