Résumé
In most countries, sanitary landfilling is the common way to dispose municipal solid wastes. In the operations, leachate treatment is a difficult and expensive process. Although, leachate can be treated by biological processes, COD removal efficiency is usually low due to high ammonium ion content and the presence of toxic compounds such as metal ions. This experimental study was conducted to investigate the effect of coagulation-flocculation process on the Hamadan landfill leachate treatment in the city of Hamedan. Also the effects of different coagulants with various dosages and pH values in the removal of chemical oxygen demand [COD] and total suspended solids were studied. Results showed that the efficiency for COD removal by Poly Aluminum Chloride at pH=12 and 2500 mg/L of coagulant, by alum at pH=12 and 1000 mg/L of coagulant dose and by ferrous sulfate at pH=12 and 1500 mg/L of ferrous sulfate dose were 60%, 62.33% and 70.66%, respectively. Also results showed that, the efficiency for Total Suspended Solids removal by Poly Aluminum Chloride that was obtained at pH=12 and 2500mg/L concentration of Poly Aluminum Chloride, by alum at pH=2 and 1500 mg/L concentration of alum and by ferrous sulfate at pH=7 and 2500mg/L of ferrous sulfate, were 39.14%, 58.37% and 35.58%, respectively. Based on results of this study, the best coagulant for COD removal was ferrous sulfate and the physico-chemical process may be used as an effective pretreatment process, especially for young leachate, prior to post-treatment [polishing] for partially stabilized leachate
Résumé
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