Dynamic Model for Anaerobic Digestion of Sewage Sludge Considering Haldane Kinetics and Wall Growth Factor

Simulation studies using dynamic model equations based on Haldane kinetics were performed to predict the optimized process parameters for anaerobic digestion of sewage sludge. Stability analysis of digester under high loading rate conditions was carried out considering wall growth factor (WGF). Initial and optimized process conditions for microbial concentration and inhibition constant were taken from batch studies. Simulation was performed by varying the values of at four constant values of . Poor process performance in terms of COD removal has been observed at lower values of , even at higher values of inhibition constant for continuous process. Maximum COD removal efficiency was observed by operating the digester at and . COD removal efficiency increased from 12% to 48% at higher loading rate of and retention time of 15 day when WGF was included in the model equation. Under similar conditions COD removal efficiency decreased from 40% to 6.6% when the loading rate was increased from 40g/L to 45 g/L, however, increase in retention time up to 20 day resulted in re-stabilized process conditions.