Research On The Recirculation Of Leachate From Garbage Landfill

The problem of municipal waste is more and more serious in our country, the amount of municipal waste is no less than 1.46 billion tons every year. Furthermore, it is constantly increasing by 9% every year, the amount of municipal waste is 1.13 billion tons in 1998. At present, the main treatment technology of municipal waste is sanitary landfill. The technology of this method is very ripe and its disposal cost is relatively low. Therefore, this method is very proper to developing country to treat municipal waste. Leachate is the principal environmental problem of landfill. Leachate is a high-density organic waste water. The decomposition of municipal garbage and the precipitation are the principal cause that produce the leachate. At present, the treatment of leachate is still a world-wide problem because of the complex component, worse biodegradability and much fluctuation of water quality and water quantity.According to the development of the abroad treatment technology of leachate and the reality of our country, recirculation technology of leachate is a kind of promising method in our country. Recycling the collected leachate to landfill can raise the ratio of containing water of garbage, and increase the humidity of garbage, and improve the activity of microbial in garbage, and improve the rate of producing methane, accelerate the decomposition of organic and shorten the stabilization process of landfill.According to those theories and facts. We have researched the process parameter of recirculation technology, biologic decomposition mechanism and the limited factor of biologic decomposition. This paper is a cooperated project with a landfill in city of Fuzhou City. The achievement of this research will be utilized in practice.The research indicates that the removal ratio of COD is very obvious by garbage column. In summer, when hydraulic load ranges from 7ml/L-d to 60ml/L-d, the change of the water quality of water discharge is very small, and the removal ratio is over 70%. In winter, because the water temperature descend and the activity of microbial reduce. Though the maximum of removal ratio of COD can reach 71%, the removal ratio of COD of water discharge has been under 60%, when hydraulic load surpasses 48.6mg/L-d. The removal ratio ofBOD5, furthermore, there is not the start-up problem of reaction container. In summer, when hydraulic load reaches 100ml/L-d, the removal ratio of BOD5 still over 80%, the removal ratio of BOD5 also can reach 80% in winter. The removal ratio of ammonia nitrogen of leachate is very obvious by garbage column. In the early term of recirculation, removal effect can reach stabilization in short term, and the removal ratio of ammonia nitrogen stabilizes over 96%.This paper discusses some effective factors of recirculation, such as temperature, recirculation cycle, hydraulic load, organic load, and pH.