Treatment of Rendering Wastewater in Microbial Fuel Cells with Nitrogen Recovery and Peroxide Production
Date: September 10, 2018
Principal Investigators: Sudeep C. Popat, Clemson University
Keywords: Wastewater, Microbial Fuel Cells
Summary:
This project sought to develop and evaluate the applicability of microbial fuel cells (MFCs) for the secondary treatment of rendering wastewater. MFCs represent an upcoming wastewater treatment technology wherein the energy embedded in the chemical oxygen demand (COD) content of the wastewater is recovered as electrical energy or as value-added products. MFCs are potentially well-suited for high-strength wastewater, such as rendering wastewater. Through the work conducted, we evaluated whether high rates and efficiencies of COD removal, concomitant with the electrical current generation, can be achieved. An additional advantage of MFCs is the separation of ammonium (NH4 +) ions produced from hydrolysis and fermentation of proteins and subsequent recovery. Although this was a goal of the project, the rendering wastewater used in this project was low on protein concentrations, and thus the prospect of nitrogen recovery was not specifically evaluated. The electrical current produced in the MFCs can be used to produce hydrogen peroxide, an important chemical for rendering plants, which can be used on-site for cleaning, disinfection, and/or odor control. Factors that affect the rate and efficiency of peroxide production were thus also evaluated. Finally, a prototype modular MFC was constructed to serve as a model for scaling up to an L-scale for a follow-up project. The future goals of work on MFCs for rendering wastewater treatment beyond those to be conducted through the next project would include exploring other co-products, as well as building a pilot-scale unit for conducting further studies.
Objectives:
The overall objective of the proposed research was to develop MFCs for secondary treatment of rendering wastewater. The specific research objectives were:
1) Demonstrate COD removal from rendering wastewater with electrical current production in the anode of MFCs, following primary treatment.
2) Optimize the rendering wastewater HRT in the anode of MFCs to achieve high rates of NH4 + transport to the cathode. This objective had to be omitted since the rendering wastewater used in the project was found to have very low protein concentrations.
3) Determine the potential peroxide production in the cathode of MFCs fed with rendering wastewater at the anode through studying different cathode parameters that affect peroxide concentrations and production efficiencies.
4) Design a modular prototype system for rendering wastewater treatment that combines the optimum anode and cathode configurations determined through Objectives 1-3.