Comparative Study on the Treatment of Landfill Leachate by Coagulation and Electrocoagulation Processes

Landfill leachate is a complex mixture of organic and inorganic compounds and their concentration level highly depends on the type of waste dumped, age of the landfill, etc. Last few decades, the researchers are exploring the feasibility of treating landfill leachate using physicochemical, biological, advanced processes and combination of these methods. The current study focused on the comparison of two commonly adopted technologies for landfill leachate treatment, chemical coagulation/flocculation and electrocoagulation process. The leachate samples were collected from two different places and examined for the following parameters: pH, turbidity, chemical oxygen demand, chlorides, alkalinity, hardness, solids and nutrients. The current study focused on studying the effect of different inorganic coagulants (alum and ferric chloride), coagulant dosages, different electrode material (titanium coated with platinum/stainless steel and aluminium/stainless steel), electrolysis time and current intensity on the removal of pollutants from leachate and reuse for non-potable applications. The raw leachates collected from the two sites were found to be significantly different in their characteristics due to the age of landfill and physiognomies of wastes dumped. The batch treatment studies showed that both the treatment systems are nearly displaying a similar kind of removal efficiency (more than 74%). Amongst that, the coagulation/flocculation process showed a better removal efficiency and cost effectiveness compared to electrocoagulation process. Additionally, the treated water was found to be not meeting the Indian Standard for inland disposal. Therefore, an additional post treatment like reed bed process or sand filtration will be a viable option for non-potable applications.