Mathematical analysis of bioelectrochemical systems

Lead Research Organisation: University of Surrey
Department Name: Chemical Engineering

Abstract

Significant amount of energy and billions of pounds are spent every year in UK to treat the industrial/domestic/municipal wastewater. However, this wastewater which typically contains a lot of organic compounds can actually be used as a valuable resource in devices known as bioelectrochemical systems (BESs). BES are like any other electrochemical cell (e.g. battery) and consist of an anode, cathode and a separating membrane (optional), but the difference lies in how the electrochemical reaction is catalysed. In BES, at least one or both of the electrode reactions are catalysed with the help of microorganisms. By combining living biological systems with electrochemistry, BES makes it possible to utilize the chemical energy from wastewater and generate electricity (microbial fuel cells, MFCs), hydrogen (microbial electrolysis cells, MECs) or value-added chemicals (microbial electrosynthesis, MES).
Among different BESs, a microbial electrosynthesis (MES) system in which both electrodes are biocatalysed, makes it possible to convert wastewater (fed at the bio-anode) and waste CO2 (fed at the bio-cathode) into useful multi-carbon compounds that are precursors to commodity chemicals and transportation fuels. Such MES systems are thus of particular interest in the context of both wastewater treatment as well as CO2 capture and utilization. The electrochemical reaction in MES is however non-spontaneous and requires external energy. Renewable energy sources (solar, wind) can be used to supply the required power. Thus MES also offers a novel way to store the renewable electrical energy in the chemical bonds of organic compounds that can be stored and transported more easily.
MES system performance depends on a number of biological, physical-chemical and electrochemical parameters. Following the first experimental demonstration in 2009-2010, a variety of studies have been conducted to investigate the effect of operational parameters on MES performance. These investigations have helped in improving the product yields however further improvements in performance require a deeper understanding of the mechanisms governing the process.
Past research on MES has extensively focused on experimental studies, while mathematical modelling has remain neglected. The development of mathematical models will be critical to the optimization and scaling of MES systems in future. At present, there are no mathematical models available to predict the overall performance of the MES process. In this project I propose to develop comprehensive mathematical models that can not only provide insight on the governing mechanisms of MES but also on how MES systems will affect the environment. Such numerical models will compliment experiments and help to develop this technology towards commercialisation at a reduced cost and time.
Development of efficient MES systems that use low-grade substrates such as wastewater and waste CO2 for chemical production provide a new technology platform for sustainable bioproduction and wastewater treatment. Such systems can help tackle environment and energy challenges in an integrated approach. Bioproduction of chemicals by consuming CO2 will also reduce the dependency on fossil fuel based carbon sources currently used in chemical industries and can assist the UK in achieving its climate targets. Thus in addition to the economic and ecological benefits, research on MES is also of major societal importance.
Though the proposed research is focused on MES systems, the insight obtained from these models will also be applicable for analogous bioelectrochemical systems such as microbial fuel cells and microbial electrolysis cells. Thus the research outcomes will contribute directly towards popularizing such sustainable technologies for bioproduction of wide range of chemicals (MES, MEC) as well as generation of renewable electricity (MFC) from wastewater.
 
Description A microbial fuel cell (MFC) is a biological fuel cell that helps convert chemical energy of wastewater into electricity with the help of bacteria. I have developed a fast converging dynamic model for MFCs which is easy to implement and is computationally inexpensive, and can thus serve as a good starting point to determine the operating conditions for fairly optimum system performance, before more comprehensive experimental/numerical studies are performed. (DOI: 10.1016/j.ijhydene.2019.04.065)
I have developed a simple correlation to calculate power density of microbial fuel cells. This correlation accounts for eight important system variables and provides an expression for dimensionless power density as a function of dimensionless external resistance, COD concentration, solution conductivity and projected surface area of anode. It captures the functional dependencies between power density and the important system parameters. (https://doi.org/10.1038/s41598-020-65375-5)

Similar to a microbial fuel cell, a microbial electrosynthesis system helps convert chemical energy of wastewater into electricity with the help of bacteria, but in this system, additional energy is provided to help reduce carbon dioxide to useful commodity chemical such as formic acid, acetic acid, etc. I have developed a mathematical model for MES which has helped in understanding the complex interdependence of operating parameters in MES. This model when compared with real experimental data showed excellent agreement. (DOI: 10.1039/C9CP01288E)
Exploitation Route The models can be used for effective multi-objective optimization of the different operating parameters of BES to achieve optimum performance based on the targeted end use.
Integration of the dynamic simulation results with techno-economic and life cycle analysis can provide a holistic understanding of the overall sustainability of different bioelectrochemical systems (BESs) such as MFC and MES.
Sectors Chemicals,Digital/Communication/Information Technologies (including Software),Education,Energy,Environment,Manufacturing, including Industrial Biotechology

URL https://tesarrec.web.app/
 
Description My research findings have been used to develop TESSAREC, a web based toolbox for techno-economic and sustainability analysis of resource recovery technologies for Circular economy. The toolbox is available online at https://tesarrec.web.app/
First Year Of Impact 2020
Sector Digital/Communication/Information Technologies (including Software),Education,Energy,Environment
Impact Types Policy & public services

 
Description MFC work with Newcastle University 
Organisation Newcastle University
Department School of Chemical Engineering and Advanced Materials
Country United Kingdom 
Sector Academic/University 
PI Contribution Dynamic simulation models of MFC which will be validated using the experimental results from Newcastle University.
Collaborator Contribution After an initial visit to the research lab of Dr. Eileen Yu at Newcastle University, we are actively collaborating on Microbial fuel cell studies. Jean-Marie, Research fellow from Dr. Eileen Yu's lab is running the experiments on MFC
Impact The collaboration combines the strength of the research groups in the two universities.. At Surrey we are mainly focused on development of theoretical models, while Newcastle is involved in experimentation on Microbial fuel cells. This collaboration has led to 1 publication so far: Influence of temperature and other system parameters on microbial fuel cell performance: numerical and experimental investigation S Gadkari, JM Fontmorin, E Yu, J Sadhukhan Chemical Engineering Journal 388, 124176
Start Year 2018
 
Title TESARREC 
Description TESARREC™ (Tool for techno-economic and sustainability analysis of resource recovery technologies for Circular economy) developed as an offshoot of our ongoing projects helps to address the challenges of sustainable development of technical systems at the human-environment interface for a circular economy. 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted 2018
Licensed No
Impact Our team has received sub-contract from a US organisation to study the sustainability of their chemical plant using TESARREC™.
 
Title TESARREC 
Description TESARREC™ (Tool for techno-economic and sustainability analysis of resource recovery technologies for Circular economy) evaluates sustainability of bioelectrochemical systems (BESs) using environmental: life cycle analysis, life cycle costing (LCC) and social life cycle assessment (SLCA),criteria, in accordance with the ISO 14040, 14041, 14044 and 26000 methodologies. 
Type Of Technology Software 
Year Produced 2019 
Impact TESARREC™ developed at University of Surrey offers robust cutting edge Life Cycle Sustainability Assessment (LCSA) methodologies with a user friendly interface for sustainable Resource Recovery from waste (RRfW) for circular economy. The tool with deep routed insights into Industrial Ecology and LCSA in accordance with the ISO 14040, 14041, 14044 and 26000 methodologies appeals to professionals that want to become a specialist in the field and hold a key decision making position in industry, non-governmental organisations (NGO) and governmental organisations or simply to understand reports in the field. 
URL https://tesarrec.web.app/
 
Description International Society for Microbial Electrochemistry and Technology (ISMET)-EU Conference (Newcastle) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact This involved a poster and oral presentation. I was able to showcase and discuss my research with over 100 academics working on microbial electrochemical technologies.
Year(s) Of Engagement Activity 2018
 
Description Waste to Wealth workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I co-organised the UKRI funded Waste to Wealth (W2W) workshops held on 11 March in Swindon and 15th March in London. The workshop was conducted in an interactive manner to engage researchers and relevant industry professionals to map out the market size and needs for resource recovery from waste (RRfW) systems.

The output from the workshop is being synthesised into policy and strategy papers to present to industries and inform policy makers.
We are also currently drafting a manuscript on sustainable reuse of food waste and a grant proposal with attendees from this workshop.
Year(s) Of Engagement Activity 2019