Municipal Solid Waste Landfill Leachate Recirculation Process

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.Simulate to the process of landfilling, the municipal refuse was classified before filling, and then, the characteristic of the leachate was analyzed in this thesis. Meanwhile, research of the recirculation technology was carried out in order to find out the disposal effectiveness of leachate's quantity, PH, COD_cr, NH₃-N concentration and chroma as a result of recirculation. This experiment was under the anaerobic circumstance.It was found that the simulated leachate took the characteristic such as complex water quality, high COD_cr, high heavy metal ion concentration ,high NH₃-N concentration as well as the large variation range of the contamination based on the research. Thus, the leachate could simulate the actual leachate.According to air temperature, the experiment could be divided into three phases: the average air temperature of the first low temperature phase was 10～-6℃, the recirculation was operated by 79days; the average air temperature of the second and third phases which belonged to intermediate temperature phases were 15℃ and 22℃. After comparing with the leachate non-recirculation and analyzing the variable rules of the water quality, the conclusions were got as follow:(1) 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.(2) During the recirculation, quantity of the leachate is influenced greatly by the air temperature. Under the three phases with different air temperature, average decrement daily of the leachate linear correlation to the air temperature, with the relational expression as follow:y=11.046x+ 83.422...