Combination of Electro-Coagulation and biological treatment by bioaugmentation for landfill leachate

This study examines the use of the coupling of electro-coagulation (EC) and biological treatment of mature landfill leachate from a non-hazardous waste storage characterized by a relatively low Chemical oxygen demand (COD) and a low BOD5/COD with a low biodegradability and a high level of inorganic compound such as NH4+. During electro-coagulation treatment, a decrease in the chemical oxygen demand (COD) was shown with an increase in the current density. A toal of 33 and 56% COD removal were respectively obtained with 23 and 95 A m−2. However, nothing was observed concerning the removal of ammonium. Nevertheless, biological treatment with or without addition of activated sludge (AS) has allowed the decrease in ammonium with a yield of 62% after 166 h. However, with the addition of activated sludge, the efficiency of nitrification is increased by 10%. As the bioaugmentation with AS has not improved the removal of organic matters and that the electrochemical treatment is not appropriate for removing NH4+, coupling treatment such as EC-biotreatment was envisaged. An integrated process involving electro-coagulation as pre-treatment of biological treatment to treat mature leachate appeared therefore relevant in the tested conditions at 23 A m−2 with a 15 and 98% global removal, respectively, of COD and NH4+.