Effect of HRT and temperature on the acidogenesis of municipal primary sludge and industrial wastewater

Two bench-scale completely mixed reactors were used to study the effect of hydraulic retention time (HRT), temperature and wastewater composition on the acid-phase anaerobic digestion process. One reactor was fed with a 1:1 mixture of starch-rich industrial wastewater and municipal primary sludge, while the other was fed with primary sludge alone. Results show that net volatile fatty acid (VFA) production and chemical oxygen demand (COD) solubilization increase significantly with the addition of the industrial wastewater and also with increase in HRT from 18 to 30 hours. In general, increase in temperature led to reduction of the net production due to poor performance of the clarifiers. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.