BIOWINTM Modeling of the Startup of an Anaerobic Digester Used in Wastewater Treatment Plants

Abstract

Anaerobic digestion involves biochemical and physiochemical processes. It is an effective process for sludge stabilization and methane gas production. However, the digester capacity decreases with time due to the buildup of solid deposits at the bottom of the digester. Therefore, routine shutdown and cleanup are commonly practiced at Wastewater Treatment Plants (WWTPs). Currently, WWTP operators face the challenge of starting up an anaerobic digester in a timely, cost-effective manner with effective methane gas production. This challenge can be addressed by computer modeling and simulations of different operating conditions, which is a cost-effective solution in comparison to experimentation. In this research, the commercially available BioWinTM software was used to build an Anaerobic Digestion Model (BioWinTM model) for the simulation of the startup of an anaerobic digester. BioWinTM dynamic simulations were conducted under different operating conditions to determine optimal seed sludge volume, sludge feed rate, and bicarbonate concentration to be used during the digester startup. Strategies for a timely and cost-effective startup using the minimum amount of available seed sludge and primary sludge feed were developed, based on the results of dynamic simulations conducted using field data gathered from the Regina WWTP. The result of this research was to decrease digester startup time and operational costs while increasing methane gas production. This will provide significant economic and environmental benefits, especially for WWTPs currently facing digester startup challenges, limited sludge treatment capacities, and low methane gas production.