[Comparison of diffrent coagulants efficiency for treatment of Hamedan landfills leachate site]

ABSTRACT

In Iran, indicated that the municipal landfill leachate has been one of the major problem for environment. In the operations, leachate treatment is a very difficult and expensive process. Although, young leachate can be treated easily by biological treatment, COD removal efficiency are usually low due to high ammonium ion content and the presence of toxic compounds such as metal ions. Treatment of leachate is necessary.The aim of this study is reduction of Chemical Oxygen Demond [COD] and Total Suspended Solids [TSS] from hamedan city sanitary landfill leachate by three coagulants alum, PAC and ferrous sulfate. This experimental study was conducted to investigate the effect of treatment of landfill leachate by a coagulation-flocculation process. The effects of different amounts of coagulant and different pH values on the coagulation processes were compared. result of this survey show that the high efficiency for COD removal by PAC in pH=12 and 2500[mg/l] concentration of PAC was 62.66%, by alum in pH=12 and 1000 [mg/l] concentration of alum was 60%, by ferrous sulfate in pH=2 and 1000 [mg/l] concentration of ferrous sulfate was 70.62%. Also result shown the high efficiency for TSS removal by PAC in pH=12 and 2500[mg/l] concentration of PAC was 58.37%, with alum in pH=2 and 1500 [mg/l] concentration of alum was39.14%, by ferrous sulfate in pH=7 and 2500[mg/l] concentration of ferrous sulfate was 35.58%. The best coagulant for COD removal is ferrous sulfate.The physico-chemical process may be used as a useful pretreatment step, especially for fresh leachates, prior to post-treatment [polishing] step for partially stabilized leachates