Landfill Leachate Treatment By Coagulation As Pre-treatment Technologies

Garbage sanitary landfill is widely applied in China and other countries as a city garbage treatment method. During the landfill of city garbage, the pollutants in garbage could be dissolved out with water and form landfill leachate with rain fall and runoff due to the compacting and microbe resolving effect. The nature and composition of the landfill leachate is very complicated and changed with the age of landfill field. At present the biological treatment is applied as main process, and physical-chemical method as pre-treatment process, land method as after treatment process in the treatment of percolate in general.Using ordinary biological method in the treatment of percolate with an elder age and poor biological degradability, the output water usually fails reaching emission standards directly or indirectly. This research is made with the landfill leachate in Tianjin Shuangkou Landfill as main object, with coagulation method as pre-treatment process. It determines the optimal coagulation agent and condition through observing the factors that affect coagulation effects. In this research condition test has been made on above factors such as dosage, mixing method, temperature, pH value, etc., and the optimal coagulation condition in the treatment of above landfill leachate has been determined by orthogonal test,The test results show that the optimal coagulation agent in above landfill leachate treatment is PFS (Polymeric Ferric Sulfate), and the optimal coagulation condition is as following: a dosage of 0.375g/L, a pH value of 7, with a mixing method 250r/min 1min 50 r/min 10min,and 40 min sediment time. In such optimal coagulation condition the CODCr removal rate can reach 40%, and SS removal rate 80%.In addition, comparison test with various coagulation agents used under same coagulation condition has also made in this research, with the changes in CODCr removal rate, SS removal rate, sludge production, total phosphorous removal rate, pH value after coagulation, and electric conductivity being observed. It is concluded that the PFS (Polymeric Ferric Sulfate) has an optimal treatment effect on the basis of all indexes.