Bio-electrochemical power generation from petrochemical wastewater using as substrates in microbial fuel cell

The petrochemical wastewater (PCW) from the acrylic acid plant possesses a very high chemical oxygen demand (COD) due to the presence of acrylic acid (AA) along with other organic acids. The treatment of PCW by conventional aerobic and anaerobic methods is energy-intensive. However, the treatment of PCW with concurrent power generation by employing microbial fuel cell (MFC) could be a potential alternative to solve the energy and environmental issues. The main hurdle for the treatment of PCW in MFC is to find out the suitable inoculum based on the substrate-inoculum interaction, to unravel the mechanism of electron transfer leading to the high power gen eration as well as high COD removal efficiency. The goal of the present work is to find out the suitable inoculum possessing electrogenic and fermentative properties, to elucidate the electron transfer mechanism and finally to investigate the anode charge transfer kinetics. MFCs were operated using PCW from local AA plant and anaerobic sludge (AS) as biocatalyst where AS was acclimatized to prepare effective inoculum. The predominated microbes were identified which include the electrogenic genera namely Pseudomonas aeruginosa (PA) and Bacillus cereus (BC) along with methanogenic archea Methanobacterium spp. The major constituents of the PCW, such as acrylic acid, acetic acid (ACA) and dimethyl phthalate (DMP) were used as feed for MFC to evaluate the substrate-inoculum interaction. The performance of the MFC was evaluated in terms of voltage/current generation as well as maximum power generation using polarization and power curve. Cyclic votammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to elucidate the kinetics of anode charge transfer and Nernst-Monod-ButlerVolmer model was used to validate and predict the performance of MFC. The results revealed that the mixed substrates with acclimatized AS could produce high power (0.78 W/m3) compared to AA with PA (0.24 W/m3), AA with BC (0.22 W/m3), ACA with PA (0.39 W/m3), ACA with BC (0.32 W/m3), DMP with PA (0.24 W/m3) and DMP with BC (0.21 W/m3 ) respectively. The power generation data was correlated with the microbial growth pattern which indicated the formation of substrates-inoculum based synergy in the mixed substrate-acclimatized AS system. The study was further extended to the real PCW which demonstrated that the PCW with an initial COD of 45,000 mg/L could generate power density of 850 mW/m2(at a current density of 1500 mA/m2) using acclimatized AS as biocatalyst. The COD removal efficiency and the coulombic efficiency (CE) were found to be 40% and 21%, respectively after 11 days of operation using initial COD of 45000 mg/L. CV investigations confirmed the role of pyocynin and hydroquinone as electron shuttles. While comparing the CV data of the biofilm and the inoculum free anolyte after 11 days of operation, the high redox peak current was observed for the latter case which clearly demonstrated the predominant role of indirect charge transfer mechanism for power generation using PCW and acclimatized AS. The charge transfer kinetics was elucidated using the Tafel slop. The kinetic parameters were evaluated by fitting the kinetic data in Nernst-Monod- Butler-Volmar model where the experimental COD and current density production was found to be in good agreement with the proposed model. The model can be used for optimization of the performance of the PCW-fed MFC. The results of the present study showed that the electrocatalytic activity of anaerobic sludge can be improved by acclimatization which can be effectively used for simultaneous power generation and treatment of PCW

Augmentation of microbial fuel cell and photocatalytic polishing technique for the treatment of hazardous dimethyl phthalate containing wastewater

In the present paper, the potentiality of integrating microbial fuel cells (MFCs) with a photocatalytic reactor to maximize the wastewater treatment efficiency with concurrent power generation was explored. Dimethyl phthalate (DMP) and acetic acid (AA) were the employed substrate and the co-substrate, respectively, using Pseudomonas aeruginosa as a biocatalyst. MFCs operated by single substrate showed the maximum power generation of 0.75–3.84 W m−3 whereas an addition of AA as the co-substrate yielded 3–12 fold higher power generation. Pseudomonas aeruginosa produced phenazine-1-carboxylic acid in DMP-fed MFC as the metabolite whereas AA along with DMP yielded pyocyanin which reduced the charge transfer resistance. Chemical oxygen demand (COD) removal efficiency in the MFCs was circa 62% after 11 days of operation. Thereafter, it further increased albeit with a drastic reduction in power generation. Subsequently, the MFC anolyte was treated in a photocatalytic reactor under visible light irradiation and catalyzed by CuO-gC3N4. The performance of photocatalytic reactor was evaluated, with COD and total organic carbon (TOC) removal efficiency of 88% and 86% after 200 min of light irradiation. The present work suggests that the MFC can be integrated with photocatalysis as a sustainable wastewater treatment method with concurrent power generation

Significant improvement of power generation through effective substrate-inoculum interaction mechanism in microbial fuel cell

Low power generation and low voltage output is a common problem in microbial fuel cell (MFC) run with complex wastewater. Biocatalysts are one of the major components to ensure the high performance of the MFCs. In the present study, palm oil mill effluent (POME) is treated with a combination of Saccharomyces cerevisiae, Klebsiella variicola and Pseudomonas aeruginosa to intensify the power generation and treatment efficiency of the MFC. MFCs are catalyzed by pure cultures exhibited low power generation in the range of 50–103 mW/m2 whereas the yeast-bacteria inoculum demonstrates 5–10 fold higher power generation (500 mW/m2 at 0.67 V) with ~90% COD removal efficiency. The mechanism of enhanced power generation by yeast-bacteria inoculum is unravelled which suggests that Klebsiella variicola and Pseudomonas aeruginosa play a crucial role in transferring the electrons from the bulk phase to the electrode surface through self-produced electron-shuttles and at the same time extract electrons from the yeast leading to high power generation. Moreover, substrate-inoculum synergism also offers higher wastewater treatment efficiency. The findings of the work suggest that the use of substrate-inoculum mutualistic interaction between yeast and bacteria as a profound replacement to the existing bacterial inoculum for achieving higher performance in MFCs

Pseudo-stem banana fiber as a potential low-cost adsorbent to remove methylene blue from synthetic wastewater

In this work, pseudo-stem banana (Musa acuminata) (PBF) fiber was utilized as a potential low-cost natural adsorbent to uptake methylene blue (MB) dye from synthetic wastewater by batch adsorption process. Different adsorption factors like contact time, pH, initial concentration, and adsorbent dosage were explored and found that the separation process is strongly pH dependent. Additionally, the adsorption data were fitted with various adsorption isotherms like Langmuir, Freundlich, Temkin, and Dubinin-Radhushkevich models to detect the adsorption equilibrium phenomena. Reaction kinetics was inspected using pseudo-first-order and second-order kinetic models. Mass transfer and intra-particle diffusion analyses indicate the adsorption mechanism of the system described particularly in the context. Furthermore, scanning electron spectroscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) were conducted to get the morphology and surface properties of the adsorbent, respectively. As a result, the as-prepared banana fiber can be proposed as a cheap suitable adsorbent to separate dyestuffs from industrial wastewater.Peer reviewe

Potentiality of petrochemical wastewater as substrate in microbial fuel cell

The petrochemical wastewater (PCW) from acrylic acid plant possesses very high chemical oxygen demand (COD) due to presence of acrylic acid along with other organic acids. The treatment of PCW by conventional methods is energy intensive. The treatment of PCW with concurrent power generation by employing microbial fuel cell (MFC) could be a potential alternative solving the problem of energy and environment. The goal of the present paper is to evaluate the viability of treating the wastewater using anaerobic sludge as biocatalyst in a dual- chamber MFC for simultaneous power generation and wastewater treatment. This study demonstrates that anaerobic sludge (AS) could work as a biocatalyst producing maximum power density of 0.75 W/m3at current density and open circuit voltage (OCV) of 412 mA/m2 and 0.45 V respectively using PCW with an initial COD of 45,000 mg/L. The COD removal efficiency and the columbic efficiency (CE) were found 40% and 13.11%, respectively. The mechanism of electron transfer in the anode was analyzed by cyclic voltammetry (CV) and the resistances across the electrode/biofilm/solution interface were investigated by employing impedance spectroscopy (EIS). The current work proves the capability of the MFC for the treatment of acrylic acid plant PCW using anaerobic sludge (AS) as biocatalyst

Photoelectrochemical activity of CuO-CdS heterostructured catalyst for CO2 reduction

The present study explored the efficiency of a p-n heterostructured hybrid catalyst CuO-CdS to convert CO2 selectively into methanol by photoelectrochemical (PEC) method under concurrent visible light irradiation and a bias potential -0.4 V vs. NHE. The results showed that the inclusion of CdS with CuO significantly enhanced the activity of PEC CO2 reduction to produce methanol by facilitating the separation of photogenerated electron-hole (e-/h+) pairs through the p-n heterostructured architectures. The yield of methanol, the incident photon current efficiency (IPCE) and quantum efficiency (QE) in PEC CO2 reduction were achieved 35.65 μmoleL-1cm-2, 20.24% and 24.11%, respectively. The present work bears a new understanding into the fabrication of high-performable artificial p-n type heterostructured catalyst which is capable to function as a catalyst for photocathode for the reduction of CO2 and remarkable improvement in methanol yield under visible light illumination

Performance evaluation of petrochemical wastewater fed air-cathode microbial fuel cells using yeast biocatalyst

This paper presents the performance of air-cathode microbial fuel cell (AC-MFC) treating the petrochemical wastewater (PCW) from acrylic acid plant. The wastewater which is typically incinerated and possesses very high chemical oxygen demand (COD) due to presence of acrylic acid along with other organic acids. The goal of the present study is to evaluate the viability of treating the wastewater using yeast (Saccharomyces cerevisiae) as biocatalyst in AC-MFC for simultaneous treatment of wastewater and electricity generation. This study demonstrates that Saccharomyces cerevisiae could function as a good biocatalyst producing high power density of 0.24 W/m3 using PCW with an initial COD of 26,000 mg/L. The COD removal efficiency and the columbic efficiency (CE) were found as 38% and 23.6% respectively. The electron transfer process across the electrode/biofilm/solution interface was analyzed by electrochemical impedance spectroscopy (EIS). The present work demonstrates the potential of MFC for the treatment of acrylic acid plant PCW using Saccharomyces cerevisiae as biocatalyst

Peformance evaluation of petrochemical wastewater fed air-cathode microbial fuel cells using yeast biocatalyst

This paper presents the performance of air-cathode microbial fuel cell (AC-MFC) treating the petrochemical wastewater (PCW) from acrylic acid plant. The wastewater which is typically incinerated and possesses very high chemical oxygen demand (COD) due to presence of acrylic acid along with other organic acids. The goal of the present study is to evaluate the viability of treating the wastewater using yeast (Saccharomyces cerevisiae) as biocatalyst in AC-MFC for simultaneous treatment of wastewater and electricity generation. This study demonstrates that Saccharomyces cerevisiae could function as a good biocatalyst producing high power density of 0.24 W/m3 using PCW with an initial COD of 26,000 mg/L. The COD removal efficiency and the columbic efficiency (CE) were found as 38% and 23.6% respectively. The electron transfer process across the electrode/biofilm/solution interface was analyzed by electrochemical impedance spectroscopy (EIS). The present work demonstrates the potential of MFC for the treatment of acrylic acid plant PCW using Saccharomyces cerevisiae as biocatalyst

Bio-electrochemical power generation in petrochemical wastewater fed microbial fuel cell

The petrochemical wastewater (PCW) from acrylic acid plants possesses a very high chemical oxygen demand (COD) due to the presence of acrylic acid along with other organic acids. The treatment of PCW by conventional aerobic and anaerobic methods is energy intensive. Therefore, the treatment of PCW with concurrent power generation by employing microbial fuel cell (MFC) could be a potential alternative to solve the energy and environmental issues. This study demonstrates the potentiality of PCW from acrylic acid plant with an initial COD of 45,000 mg L−1 generating maximum power density of 850 mW m−2 at a current density of 1500 mA m−2 using acclimatized anaerobic sludge (AS) as biocatalyst. The predominant microbes present in acclimatized AS were identified using Biolog GEN III analysis, which include the electrogenic genera namely Pseudomonas spp. and Bacillus spp. along with methanogenic archea Methanobacterium spp. The mechanism of electron transfer was elucidated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) which clearly demonstrated the natural metabolite-based electron transfer across the electrode/biofilm/solution interface. The abundance of the electron shuttle metabolites was increased with the microbial growth in the bulk solution as well as in the biofilm leading to a high power generation. The COD removal efficiency and the coulombic efficiency (CE) were found to be 40% and 21%, respectively after 11 days of operation using initial COD of 45,000 mg L−1. The low COD removal efficiency could drastically be increased to 82% when the initial COD of PCW was 5000 mg L−1 generating a power density of 150 mW m−2. The current work proves the feasibility of the MFC for the treatment of acrylic acid plant PCW using acclimatized anaerobic sludge (AS) as a biocatalyst

Catalytic performance and antimicrobial activity of Mg(OH)2/MgO colloidal nanoparticles in alkyd resin nanocomposite derived from palm oil

Colloidal Mg(OH)2/MgO nanoparticles were successfully produced in glycerol medium in the presence of hydrazine and subsequently was characterized by XRD. The as-prepared colloidal suspension in glycerol was used for the glycerolysis reaction with palm oil succeeded by polyesterification reaction with phthalic anhydride to prepare the palm oil-based alkyd resin nanocomposite where the Mg(OH)2/MgO nanoparticles catalysed the reactions. The well-dispersion of Mg(OH)2/MgO nanoparticles in the reaction mixture formed a stable suspension which effectively elevated the rate of reaction of both alcoholysis and polyesterification as compared to conventional NaOH catalysed reactions. The optimum reaction condition of the catalysts was observed at 0.04 wt% of Mg(OH)2/MgO. Alkyd resin nanocomposite formation was verified through FTIR, 13C NMR and 1H NMR. The presence of the Mg(OH)2/MgO nanoparticles in the resin matrix significantly improved the antimicrobial activity as evidenced by Kirby–Bauer Method. Thereby, the formulation of Mg(OH)2/MgO nanoparticles in glycerol medium was proved to be an effective route as compared to traditional NaOH homogeneous base catalyzed system