Comparative Analysis of Conventional Anaerobic Digestion and Bio-Electrochemical Systems in Waste Organics Utilization

Abstract

Anaerobic digestion is often used as an approach to deal with high COD waste streams. Compared to the aeration systems it allows better energy management due to the biogas production but also has several limitations including inlet waste streams quality and the additional equipment required for energy harvesting. In recent years, the bio-electrochemical systems (BES) and processes are intensively studied as a method for organic waste utilization, including wastewater. They potentially could bring several benefits to the wastewater treatment, mainly due to avoiding aeration (and aeration cost) and direct energy recovering in the form of electricity. Besides their anaerobic nature, the biological processes in BES are respiration-like contrary to the fermentative degradation typical for conventional anaerobic digestion which eventually will provide better mineralization and higher efficiency in terms of COD and BOD removal in such reactors. This study is a direct comparison between conventional anaerobic digestion and Microbial Fuel Cell (as a typical BES reactor) during utilization of wastewater from industrial production of ethanol by fermentation. COD removal rates and dynamics, energy recovery properties and parameters such as secondary sludge production are investigated in order to characterize the feasibility and technological readiness of BES as a step towards their commercialization.