Treatment of Mature Landfill Leachate from Vilappilsala by Combined Chemical and Biological Process
Mature leachate contains significant quantities of refractory organic materials that are impossible to treat efficiently by a biological process. In the present study, for the treatment of mature landfill leachate from Vilappilsala, Fenton process is adopted as chemical pretreatment prior to anaerobic process. After Fenton pretreatment removal of COD, BOD, turbidity, nitrate, sulphate and TSS were 92.1%, 83.5%, 94.2%, 18.86%, 11% and 96.6% respectively (optimized treatment conditions pH 3, reaction time 30min, H2O2/COD ratio 3, [H2O2]/[Fe2+] ratio 15 and 3g/L sludge recycling). Biodegradability (BOD5/COD ratio) enhanced from 0.3 to 0.65 and acute toxicity (96-hr LC50) reduced to 6.3% from 3%. Fenton treated leachate when post treated anaerobically at HRT 13 days and pH 7, COD, BOD, turbidity, nitrate, sulphate and TSS removal were 90.3%, 98.2%, 28.3%, 69.9%, 40% and 78.2% respectively and toxicity reduced to 22%.