A MODEL FOR EVALUATION OF ANAEROBIC DEGRADATION CHARACTERISTICS OF ORGANIC WASTE - FOCUSING ON KINETICS, RATE-LIMITING STEP

Abstract

A kinetic study for an anaerobic batch reactor was performed to evaluate quantitatively the effect of substrate characteristics on the anaerobic degradation of organic waste. The kinetic behavior of anaerobic degradation was described as a first order series reaction that is a consecutive reaction of acidogenic- and methanogenic-fermentation. DR (Determinant of Rate limiting step) that is based on balancing between the rates of the reaction steps was defined, that is the logarithmic difference between maximum acidification rate and maximum methanation rate. Anaerobic degradation characteristics, such as the kinetic and rate limiting step, could be evaluated by the value of DR. DR depended on PR (Pivotal Ratio) that is a ratio of ultimate methane yield to maximum methane production rate. PR could be obtained easily by using a first order kinetic analysis for overall anaerobic degradation, and it was considered as a useful parameter to estimate approximately the characteristics of anaerobic degradation for organic waste. This simple evaluation method for the degradation characteristics of organic waste might be used for the optimization of performance, staler operation, as well as better control and design of anaerobic digestion system.