The bio(electrochemical) production and consumption of hydrogen peroxide at a wastewater treatment plant.
Abstract: Microbial electrochemical technologies (METs) have been proposed for several approaches within the wastewater treatment arena. These technologies are possible through the activity of electroactive producing electrical current from the complete oxidation of simple organic compounds. In this talk, I will first focus on approaches in which an MET is used to produce hydrogen peroxide (H2O2) through the oxidation of primary sludge and the cathodic reduction of oxygen. Dual-chamber systems were used to collect H2O2 produced at the cathode at concentrations of up to 3.1 g/L and efficiencies of up to 80%. Single chamber MET systems allow the H2O2 produced to serve as an oxidant for primary sludge treatment, accelerating its treatment. The high efficiency of H2O2 production led to various studies on how to consume it in wastewater settings. Single-chamber systems allow the H2O2 produced to serve as an oxidant for primary sludge treatment, accelerating its treatment. At a 6-d HRT, 52% of VSS were removed and 1.2 x 105 most probable number per gram solids (dry-weight basis) of fecal coliforms were obtained, values below regulatory limits required for Class B biosolids production. On the other hand, collected H2O2 was evaluated for its capacity to provide aeration for organic oxidation in secondary treatment. The H2O2 is degraded through the activity of catalases, producing high concentrations of O2 (>20 mg/L) in the wastewater. As such, organic removal was demonstrated within 24 hours in bath reactors. This approach is currently being evaluated as an alternative to aeration of activated sludge in order to decrease emissions at wastewater treatment plants.
Bio: Dr. César I. Torres is a Professor of Chemical Engineering at Arizona State University (ASU). He is also the Associate Director of the Swette Center for Environmental Biotechnology and a member of the Center for Bioenergy and Photosynthesis, and the Center for Bio-mediated & Bio-inspired Geotechnics. His main research is bioenergy, microbial electrochemistry, and wastewater treatment; he has published over 80 articles in peer-reviewed journals on these topics. César combines biofilm modeling, electrochemical, microscopic, -omic, and analytical techniques, to characterize microbial and electrochemical kinetics and thermodynamics of microbial electrochemical technologies.
