Sustainable Solutions for Environmental Pollution. Группа авторов

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Название Sustainable Solutions for Environmental Pollution
Автор произведения Группа авторов
Жанр Биология
Серия
Издательство Биология
Год выпуска 0
isbn 9781119785415



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and engineering disciplines to reach all other disciplines including economics, politics and other social sciences. Thus, it is time for engineers, scientists, medical doctors, economists, politicians, military officers and specialists, etc., to join forces in multidisciplinary research and development projects to achieve sustainability for better, stable, peaceful, non-sectarian, prosperous and more clean and sustainable societies.

       Nour Sh. El-Gendy

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      An Overview of Electro-Fermentation as a Platform for Future Biorefineries

       Tae Hyun Chung and Bipro Ranjan Dhar*

       Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada

       Abstract

      Many countries have set up policies to decrease fossil fuel dependency and petro-based synthesis of commodity chemicals. Fermentative biofuels and bioresource recovery processes are expected to assist considerably in this context of sustainable transition to a bio-based economy. The utilization of renewable resources such as waste biomass is often considered an attractive feature of fermentative bioprocesses. However, limitations regarding the robustness of process and selectivity of target products are often considered bottlenecks to their sustainable commercialization. Particularly, in conventional fermentation processes, microorganisms produce undesired by-products to attain intracellular redox balance, which leads to a low yield of target products. Recently, electro-fermentation has emerged as an innovative approach for changing metabolic pathways of fermentative microorganisms towards target products with higher yields and productivities by changing intracellular redox potential. Lab-scale EF studies have successfully demonstrated superior performance over conventional fermentation to produce a wide variety of biofuels and commodity chemicals. This book chapter provides an overview of fundamental and applied aspects of various value-added products synthesis with the EF process and identifies research gaps for future development.

      Keywords: Electro-fermentation, electro-selective fermentation, fermentation, value-added products, biofuel, biorefinery

      Microbial electrochemical cell (MXC) is a unique type of bioreactor, which integrates biological processes (e.g., utilizing electroactive bacteria as biocatalyst) with electrochemistry (e.g., introducing electrodes, potentials) to convert the chemical energy in organic matter into bioenergy. To differentiate the various types of MXCs, different names have been assigned based on the products or their provided services. Over the decades, the MXCs were largely focused to generate bio-electricity in microbial fuel cells (MFCs) (Logan, 2008). More recently, MXCs were engineered to produce various biogas, such as bio-hydrogen in microbial electrolysis cell (MEC) (Logan et al., 2008; Wagner et al., 2009) and bio-methane in microbial electrolysis cell assisted anaerobic digester (MEC-AD) (Huang et al., 2020; Zakaria and Dhar, 2019). Nonetheless, the MXCs were also implemented for many other applications, such as water desalination in microbial desalination cell (MDC) (Al-Mamun et al., 2018; Jafary et al., 2020), nutrient recovery (Barua et al., 2019; Qin et al., 2016; Zou et al., 2017), CO2-reduction-to-value-added-products in microbial electrosynthesis (MES) (Lovley and Nevin, 2013; Rabaey and Rozendal, 2010; Zhang and Angelidaki, 2014) and production of chemicals, such as hydrogen peroxide in microbial peroxide producing cells (MPPCs) (Chung et al., 2020b; Rozendal et al., 2009). Due to the extensive studies since the early 2000s, several studies have been dedicated to scaling-up the MXCs (Dhar et al., 2016; Heidrich et al., 2014; Hiegemann et al., 2016; Liang et al., 2018; Sim et al., 2018). However, the main bottleneck of the aforementioned MXC applications was the requirement of high energy input or output, whether the electrons are the main driving force in MECs, MDCs, MES, and MPPCs, or they are the desired product (e.g., in MFCs). Often, challenges in achieving high current density from MXCs was the main argument against further development and scaling-up (Feng et al., 2014; Heidrich et al., 2014; Sim et al., 2018; Zakaria and Dhar, 2019). On the other hand, the MXCs have gained interest for further development when utilized as a biosensor, where they mainly focus on changes in electrical energy (e.g., signal output), not necessarily required to produce high electrical energy output (Chung et al., 2020a; Do et al., 2020; Jiang et al., 2018). Hence, proposing a new application of MXC focusing on using low energy input can also be a novel means.