Use of combined coagulation-adsorption process as pretreatment of landfill leachate

Landfill leachate is an important pollution factor resulting from municipal landfill sites. physical and chemicalprocesses are the better option for pretreatment or full treatment of landfill leachate. this article presents acombination of pre-treatment method (coagulation and adsorption) for leachate collected from municipal solidwaste open dumping site. physico chemical characteristics of stabilized and fresh leachate were examined.coagulation process was examined by using alum and ferric chloride. a low cost adsorbent, fly ash was used foradsorption studies. coagulation studies were carried out for fresh and stabilized leachate. adsorption studies havebeen conducted for alum pre-treated stabilized leachate. effect of coagulant dose, adsorbent dose, ph and contacttime were carried out. the effective optimum coagulant dosages were 0.6 g/l and 0.7 g/l for alum and ferricchloride respectively for stabilized leachate and incase of fresh leachate 0.8 g/l and 0.6 g/l for alum and ferricchloride respectively. for the alum pretreated stabilized leachate, the maximum cod removal is 28% using fly ashadsorbent with equilibrium time of 210 min and optimum dose of 6 g/l. overall cod removal efficiency of 82%was obtained by coagulation using alum and adsorption using fly ash for stabilized leachate. the results obtainedshowed that combined coagulation and adsorption process can be used effectively for stabilized leachatetreatment.