Temperature Effects in Anaerobic Digestion Modeling

Abstract

Temperature effects on kinetic coefficients for the biochemical processes particle disintegration, hydrolysis and substrate uptake reactions were included in the anaerobic digestion model 1 (ADM1). It was evaluated on data from a pilot experiments in a 220 liter AD sludge bed reactor treating diary manure for 4 months of varying loads and temperatures; 25, 30 and 35 °C. Implementing individual temperature effects for each biochemical reaction gave the best fit for both biogas production and intermediate products. Simulated overall soluble and particulate organic carbon removal, pH and acetate are close to measured values while propionate is underestimated. Temperature has a moderate influence on steady state biogas production in sludge bed AD (1.6 % per degree at 30 - 35 °C and 3.4 % per degree at 25 - 30 °C), implying the net energy gain can peak at T < 35 °C in some cases.