Anaerobic Removal of COD from High Strength Fresh and Partially Stabilized Leachates and Application of Multi stage Kinetic Model

Abstract

High strength fresh leachates generated at a new disposal trench, compost plant and partially stabilized leachate of an older trench were characterized in terms of anaerobic degradation at laboratory batch scale at 35oC. Fresh leachate had extremely high COD of 66,710 – 89,501 mg/L along with low pH of 4.1-5.9 in contrast to older and therefore partially stabilized leachate with a COD of about 19,000 mg/L and higher pH of 8.4. Filtration of fresh leachate samples showed to have considerable effect on continuation of degradation as for the unfiltered samples, degradation nearly stopped after a slight reduction in COD. As a first attempt, it was shown that a considerably better fit was achieved for COD variations of filtered fresh leachate samples using first order multistage kinetic model based on which hydrolysis was found to have the smallest rate, therefore being the rate limiting stage in anaerobic degradation process.