Study On Co-treatment Of Landfill Leachate And Municipal Sewage

According to the results predicted by the current trend of urbanization, the proportion of urban population in China will reach to 60% and 76% in 2030 and 2050.In the next 50 years, there will be a fastigium of the population and urbanization. The growing population means that the quantity of municipal refuse will be more and more. In "12th Five-Year plan", there will be a number of garbage harmless treatment facilities built. To 2015, the municipal refuse harmless processing rate should reach more than 80 percent .Every county in our country is required to build one garbage harmless treatment facility at least. The increase of garbage harmless treatment facilities will protect the environment and optimize the human settlement undoubtedly. However, the secondary pollution brought by harmless treatment will become more prominent, which should be think highly of. The most important way of urban garbage disposal in our country is sanitary landfill, in which landfill leachate occurs. Landfill leachate is an organic wastewater of complex concentration generated by the landfill process, because of fermentation, precipitation and water soak, which contains a huge number of refractory organics and toxic substances. If not treat properly,the pollution will do huge harm to the environment. According to literature, the leachate has already become one of the most important pollution source. The habits of our residents and garbage sorting have led to a result that landfill leachate in our country is 20% higher than that in foreign country. Therefore, landfill leachate treatment in our country is facing more pressure. By comparison, the investment and operating costs of leachate which is treated separately are higher, so consider using the co-treatment of landfill leachate and municipal water, which is much cheaper.Take the mixture of landfill leachate and municipal sewage from Baoding as a research object, using A~2O process and rotating biological contactor process respectively. Analyze kinds of problems that occur in the experiment and solve key questions as follows: (1) To determine the best hydraulic retention time, internal recycle ratio, return sludge ratio, sludge age, concentration of dissolved oxygen, water temperature and other process parameters of A~2O process. (2) To determine the best hydraulic retention time, rotary speed and disc immersion percentage and other optimum parameters of rotating biological contactor process. (3) To determine the optimum proportion of landfill leachate and municipal sewage under the optimum working conditions using two different process. (4) To make feasibility study at economic and technical feasibility analysis level. The study shows that, through dilution ,buffer, and nutrition of the municipal sewage ,under the condition of no surplus landfill leachate admission ,wastewater treatment plant can discharge satisfactorily .This not only can save the investment of landfill separate processing system, but also can reduce the running, simplify management costs, which has high economic and social benefits. Ideas and results of the study have certain reference to the combined treatment of landfill leachate.