Conversion of ammonia to electricity applied to sidestream treatment in WWTPs: characterization and improvement of electrogenic activity

Abstract

The pressing need to expand services in the sanitation and energy sectors in Brazil represents an opportunity to implement innovative and sustainable processes to reduce the energy consumption of wastewater treatment plants (WWTP). In this sense, the recent discovery of the process of direct conversion of ammonia nitrogen into electricity through bioelectrochemical systems stands out. This process has potential application for treating the high loads of ammonia nitrogen in the sidestreams of ETEs. However, fundamental aspects of the syntrophic development of biofilm associated with the anode of microbial fuel cells oxidizing ammonia are not fully elucidated, which hinders the optimization and consequent application of the process on a full scale. Thus, this research project aims to explore the effect of regulating the resistance of the external electrical circuit (Rext) on the activity of different types of bacteria (electroactive, ammonia oxidizing and anammox), aiming to increase the ammonia conversion rate in electric current. After studying the influence of Rext, the effect of the availability of organic substrate as an electron donor will be assessed, with the aim of evaluating the potential application of the process for the treatment of anaerobic digesters centrate. The evaluation of the system includes aspects of treatment efficiency and energy generation, with extensive physical-chemical and electrochemical characterization, and study of microbial ecology based on DNA extraction and 16S gene sequencing. As a result, the study will elucidate complex phenomena, contributing to the development and future implementation of this novel bioelectrochemical process in wastewater treatment systems, with potential gains for the energy sector.