Hasna Addi, Francisco Mateo-Ramírez, Víctor Ortiz-Martínez et al.

Applied Sciences • 2018

Microbial fuel cells (MFCs) are an environmentally friendly technology that can recover electricity directly from several wastes at ambient temperatures. This work explores the use of mineral oil refinery wastewater as feedstock in single-chamber air-cathode MFC devices. A polymer inclusion membrane based on the ionic liquid methyltrioctylammonium chloride, [MTOA+][Cl−], at a concentration of 70% w/w, was used as separator, showing a good efficiency in power production and chemical oxygen demand (COD) removal. The power and the chemical oxygen demand removal reached values of 45 mW/m3 and over 80%, respectively. The evolution of other parameters of the wastewater including nitrites, phosphates and sulphates were also studied. Kjeldahl nitrogen and sulphates were significantly reduced during MFC operation. The results show that mineral oil refinery wastewater can be used as feedstock in air breathing cathode-microbial fuel cells based on polymer ionic liquid inclusion membranes. This configuration could represent a good alternative for wastewater depuration while producing energy during the process.

Ibrahim M Abu Reesh, Suraj Sevda, Zhen He

Qatar Foundation Annual Research Conference Proceedings Volume 2016 Issue 1 • 2016

Petroleum refining, not only consumes large quantities of water but also generates large quantities of wastewater. Large quantities of petroleum refinery wastewater are generated worldwide, approximately 3.5–5 m 3 of wastewater generated per ton of crude oil processed. This wastewater is considered as a major source of environmental pollution. Various chemical and biologically based technologies have been developed for the treatment of petroleum refinery wastewater such as reverse osmosis, membrane filtration, electrocoagulation, anaerobic tank, anaerobic baffled reactor, aerated filter and bio-contact oxidation. In the last decade, biological treatment methods of petroleum refinery wastewater were developed because of the high cost of chemical treatment methods and these methods are also more environmental friendly. In this study, we demonstrate for the first time that it is possible to remove salt from saltwater and generate electricity while using petroleum refinery wastewater as an anodic substrate in the three chamber microbial desalination cell (MDC). MDC insinuates a new method for treating petroleum refinery wastewater and concurrently salt removal from seawater with bioelectricity generation. MDC was developed from microbial fuel cell (MFCs) concept. In this device, desalination and wastewater treatment are conducted in one system. MDC has an enormous potential as a low-cost desalination process with wastewater treatment and other benefits. MDC is a new technique in which saltwater can be desalinated without using any external energy source. The exoelectrogenic-bacteria are used in MDC reactor to oxidize biodegradable substrate in the anodic chamber and transfer the produced electrons to the anode electrode. In this study, petroleum refinery wastewater was treated in MDC using three different initial salt concentrations of 5 g/l, 20 g/L and real seawater in desalination chamber along with two separate catholyte (phosphate buffer solution and acidified water). All the three chamber MDC operations were carried out in batch mode. The maximum % COD removals of 71 and 64 were obtained using initial salt concentration of 20 g/L with MDC operated with acidified and phosphate buffer solution as catholyte respectively. The maximum desalination efficiency of 19.9% and 19.1 % were obtained in MDC operated with real seawater using PBS and acidified water as catholyte respectively. The scanning electron microscope images investigation confirmed the presence of microbial biofilm on the anode electrode and anion exchange membrane surface. The MDC performed better with acidified water compared to PBS as catholyte. The above obtained results demonstrated the feasibility of using MDC technologies to generate bioelectricity, seawater desalination and simultaneously treat complex petroleum refinery wastewater, although further studies are required to scale up and optimize the process. The MDCs are emerged as a self-energy driven device for wastewater treatment and seawater desalination at the lab scale. But still MDCs needs further research before it can be implemented at large scale. Acknowledgements: This work was made possible by NPRP grant # 6-289-2-125 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.

Emmanuel Kweinor Tetteh, Sudesh Rathilal

CBU International Conference Proceedings • 2018

The global demand for petrochemical and petroleum industry products unavoidably generates large volumes of oil refinery wastewater (ORW). The complete treatment, reclamation and disposal of the ORW to an acceptable environmental limit is currently a challenge to most of the petroleum industries. With the current development in conventional treatment methods viz. coagulation, dissolved air flotation (DAF), and biological and membrane separation processes. DAF, which is well-established separation process, effectively employs microbubbles as a carrier phase for separation. Although, DAF is frequently used in combined water and wastewater treatment plants, its fundamental characteristics and operational parameters have not yet been fully investigated for the treatment of ORW. In this study, the correlation and effects of the parameters understudy (coagulant dosage, air saturator pressure, air-water ratio and rising rate) on chemical oxygen demand, soap oil and grease, turbidity and total suspended solids removal from ORW were examined experimentally using a laboratory DAF system. The results showed that increasing the saturator working pressure and the rising rate had less effect on the system, than increasing the air-water ratio. The agglomeration of the oil droplets was found to depend solely on the polyaluminum sulphate (PAS) dosage to destabilize the oil droplets. The DAF treatability performance showed over 80% removal of the contaminants at optimum conditions of pH of 5, PAS dosage of 10 mg/L, rising rate of 15 minutes, air saturator pressure of 300-500 kPa, and air-water ratio of 5-15%. The PAS dosage was found to be the most significant factor. Therefore, a moderate increase of the PAS dosage under these optimum conditions will increase the DAF efficiency in the treatment of ORW.

S S Jaroo, G F Jumaah, T R Abbas

IOP Conference Series: Earth and Environmental Science • 2021

Abstract This system [microbial desalination cell (MDC)] is considered an excellent sustainable process to treat wastewater by biological anaerobic oxidation of the organic material by electroactive bacteria, desalinate saltwater, and electrical power generation. In the present work, MDC was used for treating oil refinery wastewater in the anode chamber by anaerobic bacteria. Simultaneously, an air pump was used to provide the oxygen to the cathode chamber as an electron acceptor to generate bioelectricity power. The power density generated by this air cathode MDC with 1KΩ external resistance at the 1 st experiment was 71.11 μW/m 2 . It increased to a peak value of 570.86 μW/m 2 at the last experiment. The maximum chemical oxygen demand (COD) removal percent of oily wastewater was 96%. The higher salinity removal rate 150.39 ppm/h with a first salt concentration in a desalinating chamber of 35000 ppm.

Jia Wang, Jiawei Liang, Yonghong Li et al.

AMB Express • 2021

Xylanases are widely used enzymes in the food, textile, and paper industries. Most efficient xylanases have been identified from lignocellulose-degrading microbiota, such as the microbiota of the cow rumen and the termite hindgut. Xylanase genes from efficient pulp and paper wastewater treatment (PPWT) microbiota have been previously recovered by metagenomics, assigning most of the xylanase genes to the GH10 family. In this study, a total of 40 GH10 family xylanase genes derived from a certain PPWT microbiota were cloned and expressed in Escherichia coli BL21 (DE3). Among these xylanase genes, 14 showed xylanase activity on beechwood substrate. Two of these, PW-xyl9 and PW-xyl37, showed high activities, and were purified to evaluate their xylanase properties. Values of optimal pH and temperature for PW-xyl9 were pH 7 and 60 ℃, respectively, while those for PW-xyl37 were pH 7 and 55 ℃, respectively; their specific xylanase activities under optimal conditions were 470.1 U/mg protein and 113.7 U/mg protein, respectively. Furthermore, the Km values of PW-xyl9 and PW-xyl37 were determined as 8.02 and 18.8 g/L, respectively. The characterization of these two xylanases paves the way for potential application in future pulp and paper production and other industries, indicating that PPWT microbiota has been an undiscovered reservoir of efficient lignocellulase genes. This study demonstrates that a metagenomic approach has the potential to screen efficient xylanases of uncultured microorganisms from lignocellulose-degrading microbiota. In a similar way, other efficient lignocellulase genes might be identified from PPWT treatment microbiota in the future.

Chenxu Zhou, Jiaming Zhang, Yuxuan Cai et al.

Separations • 2023

Rapid degradation of pulping and papermaking wastewater in a pulp and paper mill is crucial for recycling purposes yet challenging to achieve. The purpose of this research is to provide a technical guide for the ozone degradation treatment process of pulp and paper mill wastewater and to explore the reaction mechanism of dissolved and colloidal substances (DCSs). This study is vital for effectively treating pulp and paper mill wastewater through ozonation. In the catalytic ozonation process to treat pulp and paper mill wastewater, a polyurethane sponge loaded with titanium dioxide was used as a catalyst. The optimal process conditions were determined to be 8 min of treatment time, a 16 mg/L ozone concentration, pH 9, and a 7.5% catalyst filling ratio. The COD reduction under these conditions is approximately 52%. The catalytic ozonation system, according to the FI-IR and GC-MS analyses, could degrade the large-molecule volatile organic compounds in the raw wastewater into small-molecule substances. Furthermore, the relative content of common DCSs in paper wastewater, such as palmitic acid and stilbene, could be reduced. The catalytic ozonation system is more effective for treating refractory organic compounds and has a higher COD reduction than the ozonation system.

Liangliang Wang, Yuchao Fei, Chenhao Gong et al.

Water Science and Technology • 2022

Pulp and paper wastewater (PPWW) contains numerous refractory and harmful contaminants that require advanced treatment to meet the discharge criteria. This study compared the efficacy of two PPWW treatments: ultraviolet/peroxymonosulfate (UV/PMS) and ultraviolet/H2O2 (UV/H2O2) working under similar circumstances. The initial pH value, oxidant dosage, UV radiation intensity, and pseudo-first-order constant kobs were systematically studied in both systems. Optimally, the UV/PMS process produced an effluent of higher quality than the UV/H2O2, as measured by the removal efficiencies of chemical oxygen demand (COD) in 60 min, which were 48.2 and 64.3% for the respective UV/H2O2 and UV/PMS processes and corresponding kobs values of 0.0102 and 0.0159 min-1, respectively. Radical scavenging experiments demonstrated that •OH was the primary reactive oxygen species in UV/H2O2 process, and •OH and SO4-• in the UV/PMS process. Moreover, ultraviolet-visible spectroscopy and gas chromatography coupled mass spectroscopy analyses showed that deep treatment of petroleum hydrocarbons with carbon chain lengths greater than 18 and macromolecular semi-volatile organic compounds in paper wastewater is difficult, whereas the UV/PMS process can significantly improve the removal of amides, esters, phenols, and other aromatic compounds.

A. Jagaba, S. Kutty, A. Noor et al.

Journal of Hunan University Natural Sciences • 2022

Paper and pulp industrial processes lead to the discharge of wastewater that contains high pollutants concentrations into the environment, which subsequently contaminate freshwater. Thus, it necessitates a sustainable treatment approach. This study focused on the start-up of the bench-scale activated sludge system fed with pulp and paper wastewater to verify the influence of HRT, wastewater concentration, and sugarcane bagasse on COD and ammonia removal efficiencies during the treatment process. An activated sludge process was operated at a flow rate of 5 L/day, while the reactor kept running at 72 h, 48 h, and 24 h HRT, respectively. Wastewater concentrations were set at 1039, 3158, 5248 mgCOD//L and 13.74, 40.37, 67.04 mgNH4+-N/L corresponding to 10, 50 and 100% respectively. Findings revealed high removal efficiencies up to 98.11% and 92.67% for COD and ammonia, respectively. After treatment, effluent concentrations for both parameters have satisfactorily met the Standard "A" standard limits for industrial discharge at 48 hours HRT. Therefore, further testing is not required. The First order and Modified Stover-Kincannon models evaluated substrate removal rates. In the Modified Stover–Kincannon model, high correlation coefficients R2 of 0.9999 and 0.9998 were obtained for COD and ammonia, respectively. Unfortunately, the activated sludge process in the bioreactor could not be described by the first-order kinetic model. The modified Stover-Kincannon model proved to best suit the experimental data.

J. Amacosta, T. Poznyak, Sergio Siles et al.

Toxics • 2024

In this research, the decomposition of toxic organics from pulp and paper mill effluent by the sequential application of ozonation and biodegradation was studied. Ozonation, as a pre-treatment, was executed to transform the initial pollutants into less toxic compounds (such as organic acids of low molecular weights). Biodegradation was executed during three days with acclimated microorganisms that were able to complete the decomposition of the initial organic mixture (raw wastewater) and to achieve a higher degree of mineralization (85–90%). Experiments were performed under three different conditions: (a) only ozonation of the initial contaminants, (b) only biodegradation of residual water without previous treatment by ozone and (c) ozonation followed by biodegradation performed by acclimated microorganisms. In the case of 72 h of biodegradation, the mineralization efficiency reached 85% and 89% after 30 and 60 min of ozonation, respectively. The no significant difference in this parameter coincided with the calculated generalized microorganisms’ consortia specific growing rate μmax that was reduced from 2.08 × 10−3 h−1 to 6.05 × 10−4 h−1 when the ozonation time was longer. The identification of the organics composition by gas chromatography with mass detector (GC-MS) before and after treatments confirmed that the proposed combined process served as a more efficient alternative to secondary and tertiary treatments (mineralization degree between 60 and 80% in average) of the paper industry wastewater.

Dian Pisceselia, S. Arita, T. Agustina

Journal of Ecological Engineering • 2023

The wastewater generated from pulp and paper production still contains pollutants and contaminants, so appropri-ate and economical materials are needed to reduce pollutants by using adsorbents from bottom ash. This study ex-amined the characteristics of bottom ash and pulp and paper wastewater, the effect of stirring time, stirring speed, and adsorbent activation temperature on decreasing the environmental parameters of wastewater. The synthesis of bottom ash as an adsorbent was carried out by heating at 100 and 200 °C for 1 hour. The wastewater treatment process with maximum yield occurs at a stirring speed of 100 rpm for 50 min. The use of bottom ash without heating as an adsorbent in the pulp and paper wastewater treatment process has reduced TSS 77.5%, COD 85.72%, chloride 26.9%, TDS 1143 ppm, and EC 2180 s/cm, which have met the environmental quality standards.

T. Javeed, Rab Nawaz, S. Al-Hussain et al.

Water • 2023

The present study was conducted in order to investigate the efficiency of different advanced oxidation processes both individually and in combination with the biological method for the removal of color and chemical oxygen demand (COD) from wastewater in the pulp and paper industry. Advanced oxidation processes include ozone, Fenton, hydrogen peroxide, and photo-Fenton. Biologically treated wastewater was successively subjected to advanced oxidation processes (AOPs). The optimum conditions for the ozone treatment of raw wastewater were found to be a contact time of 9 min and a pH of 5 at a fixed dose of ozone for a removal efficiency of 41.22% for color and 88.53% for COD. Similar optimum conditions for the ozone treatment of biologically treated wastewater showed a removal efficiency of 46.36% for color and 95.92% for COD. The photo-Fenton process also showed an efficiency comparable to the ozone treatment for both raw wastewater and biologically treated wastewater, resulting in a removal efficiency of 39.85% (color) and 90.13% (COD) for raw wastewater, and of 41.34% (color) and 94.29% (COD) for biologically treated wastewater. Each had a contact time of 12 h. The Fenton oxidation of raw wastewater showed a removal efficiency of more than 26.30% for color and 86.33% for COD. Fenton oxidation, however, showed an efficiency of 26.62% for color and 84.49% for COD removal from biologically treated wastewater. Hydrogen peroxide showed an efficiency of 28.45% for color and 85.13% for COD removal from raw wastewater, and 39.48% for color and 86.53% for COD removal from biologically treated wastewater. The results for the raw wastewater treatments indicated that higher removal efficiencies can be achieved when they are used as pre-treatments. Biological treatment is a cost-effective method but it has less efficiency for color removal. In combination with one of the AOPs, either as a pre- or post-treatment under a controlled time and dose, biological treatment increased the efficiency, making treatment feasible at larger scales.

Xiaoli Liang, Yanpeng Xu, Liang Yin et al.

Water • 2023

The pulp and paper industry plays an important role in the global economy and is inextricably linked to human life. Due to its large scale, the production process generates a large amount of wastewater, which poses a major threat to the environment. The sustainable utilization and safe treatment of pulp and paper wastewater can effectively reduce environmental pollution, improve resource utilization efficiency, protect water resources, provide economic benefits for pulp and paper enterprises, and thus promote the green and sustainable development of the pulp and paper industry. Therefore, this study discusses the pollution components of pulp and paper wastewater and their impact on the environment and human health. In this review, we aim to explore the sustainable development of pulp and paper wastewater by summarizing the characteristics of current pulp and paper wastewater, the commonly used treatment methods for pulp and paper wastewater, the application of pulp and paper wastewater recycling, and the future development direction of pulp and paper wastewater.

Amar Abhishek, A. Dwivedi, Neeraj Tandan et al.

Applied Water Science • 2017

AbstractContinuous discharge of lignin containing colored wastewater from pulp paper mill into the environment has resulted in building up their high level in various aquatic systems. In this study, the chemical texture of kraft lignin in terms of pollution parameters (COD, TOC, BOD, etc.) was quite different and approximately twofold higher as compared to model lignin at same optical density (OD 3.7 at 465 nm) and lignin content (2000 mg/L). For comparative bacterial degradation and detoxification of model and kraft lignin two bacteria Citrobacter freundii and Serratia marcescens were isolated, screened and applied in axenic and mixed condition. Bacterial mixed culture was found to decolorize 87 and 70 % model and kraft lignin (2000 mg/L), respectively; whereas, axenic culture Citrobacter freundii and Serratia marcescens decolorized 64, 60 % model and 50, 55 % kraft lignin, respectively, at optimized condition (34 °C, pH 8.2, 140 rpm). In addition, the mixed bacterial culture also showed the removal of 76, 61 % TOC; 80, 67 % COD and 87, 65 % lignin from model and kraft lignin, respectively. High pollution parameters (like TOC, COD, BOD, sulphate) and toxic chemicals slow down the degradation of kraft lignin as compared to model lignin. The comparative GC–MS analysis has suggested that the interspecies collaboration, i.e., each bacterial strain in culture medium has cumulative enhancing effect on growth, and degradation of lignin rather than inhibition. Furthermore, toxicity evaluation on human keratinocyte cell line after bacterial treatment has supported the degradation and detoxification of model and kraft lignin.

Fu Chen, Siyan Zeng, Zhanbin Luo et al.

Separation Science and Technology • 2020

ABSTRACT In this study, a system combining an anaerobic moving-bed biofilm reactor and a microbial fuel cell (MFC) was designed for simultaneous bioelectricity generation and pulp/paper wastewater (PPW) treatment. After 22 days, when hydraulic retention time (HRT) was set at 72 h, ceramsite-added MFC (C-MFC) showed better bioelectricity performance with power density of 94.5 mW/m2 and internal resistance of 35.7 Ω, as compared to the control without ceramsite (W-MFC) (56.1 mW/m2, 54.3 Ω). Chemical oxygen demand (COD) removal efficiencies of C-MFC and W-MFC were 65.6% and 51.3%, respectively. The C-MFC demonstrated its superior electrochemical performance compared to the W-MFC.

Anju Malik, Shaveta Kakkar, Sanjeev Gupta

Journal of Applied and Natural Science • 2018

The study aims to explore the beneficial use of fly ash and its effectiveness as low cost adsorbent for wastewater treatment of Pulp and paper industry. A comparative study was also carried out for the better colour reduction of industrial effluent using fly ash and commercial activated carbon. Batch mode adsorption experiments were carried out to optimize the different experimental conditions like adsorbent dose, contact time, rotation per minute (RPM) and pH. The treatment showed that the removal efficiency of colour increased to 86 % with the increase in adsorbent dose (0.5 – 10 g), time (30–240 min), RPM (50 - 150) and pH (4–12) of pulp and paper industry wastewater. The removal efficiency of activated carbon was found to be 100 % using 1 g adsorbent dose of commercial grade activated carbon. The Scan Electron Microscope (SEM) results of the fly ash showed that the particles looked like somewhat spherical large particles. It was concluded that though the activated carbon was very efficient adsorbent in comparison to fly ash, the better solution for disposal of solid waste such as fly ash can be good a substitute as the adsorbent for the colour reduction of the paper mill wastewater.

Josivaldo Sátiro, André Cunha, Ana P. Gomes et al.

Applied Sciences • 2022

The microalgae–bacteria consortium is a promising and sustainable alternative for industrial wastewater treatment, since it may allow good removal of organic matter and nutrients, as well as the possibility of producing products with added value from the algae biomass. This research investigated the best bacterial and microalgae inoculation ratio for system start-up and evaluation of removing organic matter (as chemical oxygen demand (COD)), ammoniacal nitrogen (NH4+–N), nitrite nitrogen (NO2−–N), nitrate nitrogen (NO3−–N), phosphate phosphorus (PO43−–P) and biomass formation parameters in six photobioreactors with a total volume of 1000 mL. Reactors were operated for 14 days with the following ratios of pulp mill biomass aerobic (BA) and Scenedesmus sp. microalgae (MA): 0:1 (PBR1), 1:0 (PBR2), 1:1 (PBR3), 3:1 (PBR4), 5:1 (PBR5), and 1:3 (PBR6). Results show that COD removal was observed in just two days of operation in PBR4, PBR5, and PBR6, whereas for the other reactors (with a lower rate of initial inoculation) it took five days. The PBR5 and PBR6 performed better in terms of NH4+–N removal, with 86.81% and 77.11%, respectively, which can be attributed to assimilation by microalgae and nitrification by bacteria. PBR6, with the highest concentration of microalgae, had the higher PO43−–P removal (86%), showing the advantage of algae in consortium with bacteria for phosphorus uptake. PBR4 and PBR5, with the highest BA, led to a better biomass production and sedimentability on the second day of operation, with flocculation efficiencies values over 90%. Regarding the formation of extracellular polymeric substances (EPS), protein production was substantially higher in PBR4 and PBR5, with more BA, with average concentrations of 49.90 mg/L and 49.05 mg/L, respectively. The presence of cyanobacteria and Chlorophyceae was identified in all reactors except PBR1 (only MA), which may indicate a good formation and structuring of the microalgae–bacteria consortium. Scanning electron microscopy (SEM) analysis revealed that filamentous microalgae were employed as a foundation for the fixation of bacteria and other algae colonies.

Alireza Seify, Hassan Ahmadi, Majid Peyravi et al.

Archives of Hygiene Sciences • 2023

Background & Aims: The membrane adsorption bioreactor (MABR) process is the integration of biological treatment and membrane technology. Accordingly, in this study, an MABR was employed for the pulp and paper industry wastewater treatment. Materials and Methods: The purchased powdered activated carbon (PAC) was added to the system as an adsorbent which improved the flux of the membrane. Results: Based on the obtained results, the organic compounds were successfully removed by the average removal of 62% and 86% without and with an adsorbent, respectively. Moreover, the activated sludge was prepared from the Babol-Toyoor Slaughterhouse wastewater treatment, and adding the PAC to the activated sludge led to the better performance of the MABR system by providing a proper condition for microorganism growth. Monitoring the mixed liquid suspended solids during the process demonstrated that increasing mixed liquor suspended solids (MLSS) increased the contaminant removal rate. Conclusion: Overall, the presence of PAC could prevent microorganisms from accumulating on the membrane surface.

Sahar A. Mousa, Heba Abdallah, S. A. Khairy

Scientific Reports • 2025

Abstract The pulp and paper manufacturing wastewater is as complicated as any other industrial effluent. A promising approach to treating water is to combine photocatalysis and membrane processes. This paper demonstrates a novel photocatalytic membrane technique for solar-powered water filtration. The method is based on creating green-prepared TiO 2 , and MnO 2 nanoparticles (NPs) using Pomegranate peels and Seder leaf extracts and incorporation into polyvinylidene chloride to produce a novel water purification system that combines semiconductor photocatalysis with membrane filtration. The prepared heterostructure of the TiO 2 /MnO 2 nanocomposite membrane provides photogenerated charge separation. To ensure chemical bonding at the membrane surface, Raman and Fourier transform infrared spectroscopy (FT-IR) were employed. The modified membrane’s hydrophilicity and roughness increased significantly. Additionally, the modified nanocomposite membrane ’ s porosity was measured. The integrated process demonstrated much higher removal of humic acid and high efficiency of wastewater treatment for pulp and paper. In sunlight, humic acid removal was 98% from synthetic wastewater. While using the produced membrane on pulp and paper effluent, these studies indicate that: in the dark, the removal was 50%, while in the sunlight, the removal increased to 70%, with a reduction in the COD from 1500 mg/L to 247 mg/L. Additionally, the TDS decreased from 1630 to 452 ppt in the sunlight. This research sheds light on how solar energy can clean wastewater from the pulp and paper industry while improving membrane separation. Also, an alternative source to sunlight was used to manufacture a photocatalytic membrane with high efficiency for wastewater treatment and an inexpensive price.

Hanumanthappa Srikantha, Ashwini D Guruswamy, Shivaswamy Mahesh et al.

ECS Transactions • 2022

SS and Cu electrodes were used in the electrochemical coagulation to treat pulp and paper mill wastewater using 4SS and 3SS 1Cu electrodes by applying cell voltages 12 – 24 V. Optimal cell voltage 18V showed COD removal of 89.64% for 4SS electrode and 84.74% for 3SS 1Cu electrode with simultaneous color removal of 99% and 90%. Other control factors used for optimal operation are sludge volume index (SVI), filterability, etc. SVI values were <100 mL/g for 4SS electrodes. The filtration characteristics of the ECC-treated sludge were established to determine the specific cake resistance (α) and the resistance of the filter medium (R m ). Lower α and R m values for 4SS and 3SS-1Cu electrodes were found at 60 min ET. Proximate and ultimate analyses showed that 4SS and 3SS-1Cu sludge could be used as additive as well as adsorbent material for treating low strength wastewater.

Arif Sasongko, Marcellino Agung Christyo, Alexander Marcelino Krismono et al.

Komputika : Jurnal Sistem Komputer • 2022

As one of the largest wastewater producers in the world, the pulp and paper industry need to monitor the waste that they generated. To carry out this monitoring process, the majority of the pulp and paper industry still uses conventional offline methods to measure parameters in their wastewater treatment plants. The monitoring procedure is carried out by taking samples from the factory wastewater treatment plant and testing these samples in the laboratory. This procedure is very prone to errors caused by human. This method also cannot detect any violation, problem, or disturbance of the wastewater parameters in real time. In addition, in 2018, the Indonesian Ministry of Environment and Forestry issued a regulation requiring the pulp and paper industry to use a real-time online monitoring system for its wastewater treatment plant. This paper presents an implementation of the system. There are several parameters that must be measured, two of them are pH and TSS (Total Suspended Solids). To measure these parameters, the regulation states that the online measurement system is carried out using the relevant electric probe sensor. Then the measurement results are displayed online on a specified platform hence that users can observe the results. This implementation uses a pH sensor to measure pH and a conductivity sensor to measure TSS. A conductivity sensor is used as a substitute due to the high cost of TSS sensor. This article analyses also the accuracy of the measurement.

Vishnuprasad Selvaraj, Prasanna Kumar S. Mural, Abdul Rehman et al.

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

The rapid growth of industrialization has heightened the demand for energy, leading to increased pressure on finite petroleum resources. Consequently, research efforts have intensified to explore renewable and sustainable energy sources. Microbial fuel cell (MFC) technology has emerged as a promising bioelectrochemical platform, capable of generating bioelectricity while utilizing microorganisms to degrade organic contaminants found in wastewater. However, the successful scaling-up of MFCs remains a significant technical challenge, hindering their practical application. This chapter delves into the power generation potential of MFCs using various industrial wastewater substrates. It underscores the influence of crucial factors on cell performance, including substrate type, quantity, pH levels, and temperature regulation within the chambers. Despite its numerous advantages, this technology also presents certain challenges and potential outcomes, particularly concerning energy recovery from the effluents processed within MFCs.

Sumit Dagar, Santosh Kumar Singh, Manoj Kumar Gupta

Frontiers in Environmental Science • 2022

Paper mills generate large quantities of wastewater and sludge waste depending on the type of paper making processes employed. This poses several problems regarding wastewater treatment, discharge, and sludge disposal. Whenever wastewater is generated, it should be treated in wastewater treatment plants prior to being released to the environment since it can be polluting and dangerous. A study was conducted at Star Paper Mills Ltd. Saharanpur, UP to demonstrate the existing and advanced technologies for wastewater treatment. The mill uses woody raw materials such as eucalyptus, poplar, and veener chips to manufacture a wide range of industrial and cultural grade papers, such as absorbent kraft, maplitho, azure lay, and copier. We observed that the most common excess back water is from paper machines, bleach plant effluent, floor cleaning, and other sources of wastewater. High chemical oxygen demand (COD), biochemical oxygen demand (BOD), and low biodegradability are all characteristics of pulp and paper wastewater. Approximately 85–90% of the fresh water utilized is wasted. We examined the wastewater collected and evaluated from the paper mill by Central Pulp and Paper Research Institute (CPPRI). The Effluent treatment plant (ETP) at Star Paper Mills Ltd. is sufficient to facilitate satisfactory removal of suspended matter in clarifiers and oxidation of biodegradable organic matter in aeration tank. As a matter of fact, if the ETP is operated under optimal conditions, the aeration capacity is sufficient to effectively treat even higher BOD loads than the existing load.

J. PALUMBO, P. CYR, R. SACKELLARES et al.

TAPPI Journal • 2015

Secondary wastewater treatment aeration systems are an integral part of many mills’ pollution control operations. Several factors can drive the need for aeration system performance upgrades, including changing mill production regimes, increased environmental compliance requirements, and equipment deterioration. However, optimal upgrade designs can be difficult to achieve because of the many interrelated and site-specific factors that influence secondary treatment performance. This article is intended as an introductory resource to understanding and addressing the complexities often associated with achieving an optimal aeration system upgrade. Relevant aeration and mixing science fundamentals and commonly employed aeration technologies are summarized and reviewed. The application of wastewater treatment computer models is examined as it pertains to aeration system design and operation. Recommendations for aeration system upgrade projects include specific information needs, potential resource requirements, general model selection guidance, and discussion of potential model application methodologies.

Abolghasem Alighardashi, Meghdad Modanlou, Shervin Jamshidi

Water Practice and Technology • 2015

This essay outlines the use of an anaerobic baffled reactor (ABR) treating pulp and paper wastewater during its start-up period. For this purpose, a pilot with four chambers and overall volume of 45 liters was fed continuously through the equalization tank of Mazandaran wood and paper wastewater treatment plant, in the north of Iran. The influent was classified as low strength slowly biodegradable wastewater. The average soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD) of the influent were about 1,130 and 320 mg/L, respectively. Results show that the start-up was accomplished in 90 days in which the ABR reached its maximum SCOD removal of 60%. This was achieved at the controlled mesophilic temperature (37 °C) and optimum hydraulic retention time (HRT) of 24 hours. In spite of the influent characteristics, the performance of ABR has not been inhibited and mostly influenced by HRT. The gradual hydrolysis and acidogenesis were observed within the ABR. The majority of chemical oxygen demand (COD) removal takes place in the first chamber. In addition, the concentrations of readily biodegradable organics (BOD to COD ratio) have been increased and doubled through the reactor. Moreover, the total values of pH, volatile fatty acids and alkalinity remained constant. Consequently, this system can be approved for application as a pretreatment unit for paper mill industrial wastewater treatment plants.

Chhotu Ram, Pushpa Rani, Kibrom Alebel Gebru et al.

Physical Sciences Reviews • 2020

Abstract Pulp and paper industry is coming under one of the most water polluting industries, and generated wastewater is highly toxic in nature. The paper mill requires huge quantity (~50–60 m 3 of water to produce one ton of paper) of water, and accordingly huge quantity of chemical contaminated wastewater is discharged. The paper mill effluents have identified 240–250 chemicals in different stages of paper making. Various chemical constituents such as high chemical oxygen demand, biochemical oxygen demand, AOX, chlorinated compounds, color, suspended materials, lignin and their derivatives are released in the wastewater. The present review study is focused on the paper mill processes, wastewater generation and its effective treatment by microorganisms. The biological treatment has been identified as cost-effective and eco-friendly methods for the degradation of xenobiotic compounds for paper mill wastewater. Various studies have been performed so far to investigate the complex nature of wastewater by the application of bacteria, fungi and their enzymes at industrial scale. Therefore, the article discussed the importance of biological method as an effective technique for the degradation of paper mill wastewater.

Matia Mainardis, Silvia Mulloni, Arianna Catenacci et al.

Sustainability • 2022

In this work, different alternatives to conventional tertiary treatment of pulp and paper (P&P) wastewater (WW), i.e., physicochemical coagulation-flocculation, were investigated to enhance the environmental and economic sustainability of industrial wastewater treatment. In particular, following a preliminary characterization of secondary effluents, cloth filtration and adsorption were studied, the former by pilot-scale tests, while the latter at laboratory scale. An economic analysis was finally accomplished to verify the full-scale applicability of the most promising technologies. Cloth filtration showed excellent total suspended solids (TSS) removal efficiency (mean 81% removal) but a very limited influence on chemical oxygen demand (COD) (mean 10% removal) due to the prevalence of soluble COD on particulate COD. Adsorption, instead, led to a good COD removal efficiency (50% abatement at powdered activated carbon—PAC—dosage of 400 mg/L). The economic analysis proved that adsorption would be convenient only if a local low-cost (100 €/ton) adsorbent supply chain was established. Ultrafiltration was considered as well as a potential alternative: its huge capital cost (19 M€) could be recovered in a relatively short timeframe (pay-back time of 4.7 years) if the ultrafiltrated effluent could be sold to local industries.

AMANDA JOHANSEN MATTINGLY, PAUL WIEGAND, ROBERT SACKELLARES

TAPPI Journal • 2022

Many pulp and paper mills are, at least periodically, faced with the release of odors that can migrate offsite and be considered a nuisance by nearby residents. At chemical pulp mills, perceptible odors associated with reduced sulfur compounds (RSCs) are common, many of which are highly perceptible owing to their low odor thresholds. As releases of RSCs and other odorous substances from production processes are progressively controlled, the proportional contribution from wastewater treatment systems to areal odors can increase. This review paper summarizes important fundamentals of odor generation, source identification, and control. Common odorous substances are identified, and mechanisms for their generation are summarized. Approaches for measuring odorous substances are detailed to enable more effective management, and various odor control strategies are discussed.

Vita HALYSH, Iaroslav RADOVENCHYK, Mykola GOMELYA et al.

Herald of Khmelnytskyi National University. Technical sciences • 2022

Nowadays, more than 80% of cardboard and paper products of Ukrainian mills are made from waste paper – secondary fibers that differ in their chemical and physical properties from primary cellulosic fibers. Characteristic feature of secondary fibers is the presence of a large number of small fibers, which negatively affects the quality of finished products, mass retention on the grid during the formation of paper or cardboard, which leads to pollution of wastewaters. Despite its environmental friendliness and economy, waste paper is also characterized by the presence of various pollutants, the formation of which is associated with the process of paper formation, storage of finished products, and their use. As a result of the preparation of the mass from secondary fibers, there is a transition of pollutants from the waste paper to the wastewater in the form of colloidally dispersed and soluble substances, which lead to the pollution of circulating water. Purification of water and its reuse in technological processes is an important task of paper industry mills. The results show that more than 90% of the secondary fibers have a length that does not exceed 1 mm, while in the primary cellulose fiber from coniferous wood about 53% of the fibers have a length of more than 1 mm. The high content of short fibers in the paper mass affects the processes of paper formation, worsening them, and a decrease in the retention of the fiber on the grid of the paper or cardboard machine is observed, causing the pollution of wastewater. The results of the study of coagulation of industrial wastewater with the content of suspended solids 1520 and 3200 mg/dm3 from the production of cardboard from recycling paper show that the best coagulants are A1(OH)C12 and A12(OH)5C1. The maximum efficiency of water purification of only 92.5% was achieved at the suspended solids content of 1520 mg/dm3, while for wastewater with a suspended solids concentration of 3200 mg/dm3 98.0% was obtained. To develop a scheme for deep purification of wastewaters, it is important to understand which components are removed from water more easily and which are more difficult during coagulation. For this purpose, studies on coagulation of model suspensions of starches, bentonite and kaolin using inorganic coagulants were conducted. It was established that coagulation of native corn starch suspension with inorganic coagulants is effective. However, in the case of using modified starches, the removal of cationic starches is reduced. The efficiency of water purification in the removal of bentonite by sedimentation-filtration with the use of coagulants is quite high. The degree of purification reaches 80.8-98.1%. The filtering stage allows the degree of purification to be further increased. Research on the processes of purification of model kaolin suspensions shows that mechanical and physico-chemical methods are ineffective in removing this mineral filler.

Farial Orion, Most Ismo Ara Labony, Sadman Sakib Ornob et al.

Chemical Engineering Research Bulletin • 2023

The unregulated discharge of textile wastewater has a detrimental effect on soil, air, and water, releasing hazardous contaminants such as dyes, heavy metals, and organic materials into the ecosystem. This study investigated the practical application of solar microbial electrolysis using Aspen Plus. It is an effective method of understanding pilot-scale biohydrogen production. The simulation environment highlights the promise and versatility of solar microbial electrolysis cells. Utilizing 2000 kg of textile wastewater as a substrate, 33.56 kg was produced; this comprehension model also included a hydrogen separation and storage section. The hydrogen storage conditions are optimized at 150 bar and 40°C. This simulation also quantifies the changes in enthalpy and entropy in different stages of the SMEC plant. Maximum enthalpy was observed in the final product of the simulation. Chemical Engineering Research Bulletin 23 (2023): 11-16

Anil Dhanda, Akash Tripathi, Rishabh Raj et al.

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

The increasing demand for potable water and the negative impacts of industrial wastewaters on freshwater sources have necessitated the development of new technologies for holistic wastewater treatment. Constructed wetland–microbial fuel cell (CW–MFC) is an innovative and sustainable technology that combines the benefits of both CW and MFC. The wetland component provides conducive habitat for microbial growth, while the fuel cell generates electricity from microbial activity while treating wastewater. The same approach can potentially remove a wide range of recalcitrant pollutants from industrial effluents in addition to organic matter, nitrogen, and phosphorus. This technology consumes less energy, has low operating/maintenance costs and simultaneously produces renewable energy from waste streams, which makes it superior to traditional wastewater treatment technologies. The current chapter explores different types of CW–MFC systems evolved for wastewater application, emphasizing the fundamental principles, design considerations, and operation mechanisms of these systems. Further, the efficacy of CW–MFC for the treatment of a variety of industrial wastewaters, such as dairy, brewery, and pharmaceutical wastewater, is also elucidated. The chapter also highlights the challenges and limitations of the CW–MFC-based technologies and the measures required to improve their performance and scalability aspects.

Joshua M. Lawrence, Yutong Yin, Paolo Bombelli et al.

Science Advances • 2022

Synthetic biology research and its industrial applications rely on deterministic spatiotemporal control of gene expression. Recently, electrochemical control of gene expression has been demonstrated in electrogenetic systems (redox-responsive promoters used alongside redox inducers and electrodes), allowing for the direct integration of electronics with biological processes. However, the use of electrogenetic systems is limited by poor activity, tunability, and standardization. In this work, we developed a strong, unidirectional, redox-responsive promoter before deriving a mutant promoter library with a spectrum of strengths. We constructed genetic circuits with these parts and demonstrated their activation by multiple classes of redox molecules. Last, we demonstrated electrochemical activation of gene expression under aerobic conditions using a novel, modular bioelectrochemical device. These genetic and electrochemical tools facilitate the design and improve the performance of electrogenetic systems. Furthermore, the genetic design strategies used can be applied to other redox-responsive promoters to further expand the available tools for electrogenetics.

Shamima Mehrin, Nilufer Yesmin Tanisa, Rabiul Awal et al.

Advances in Materials Science and Engineering • 2024

The present study investigates an environmentally conscious method for synthesizing silver nanoparticles (AgNPs) by employing extracts from pomegranate peel (PgP) and pineapple peel (PnP). This green synthesis approach offers a sustainable alternative to traditional chemical methods, thereby reducing the ecological footprint associated with nanoparticle production. The PgP and PnP extracts serve as both reducing and capping agents during the synthesis process, enhancing the biocompatibility of the resultant AgNPs. Various characterization techniques, including UV-Vis spectroscopy, Raman analysis, X-ray diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared (FTIR), and transmission electron microscopy (TEM), were utilized to analyze the synthesized AgNPs. UV-Vis spectroscopy confirmed the formation of AgNPs through characteristic surface plasmon resonance peaks, while FTIR examined the interaction between biomaterial components and the oxidation and coating of silver nanoparticles. Raman analysis elucidated the functional groups responsible for reducing and stabilizing AgNPs, while XRD provided insights into their crystalline structure. TEM images revealed the size and morphology of the nanoparticles, while DLS characterized their average size and morphology. In addition, the synthesized AgNPs were utilized in a bioelectrochemical cell to leverage their unique properties for enhanced electrochemical performance, showcasing their potential application in energy storage and conversion systems. Overall, this study demonstrates the feasibility of utilizing agricultural waste products such as PgP and PnP for sustainable AgNP synthesis, offering promising prospects for environmentally friendly nanotechnology advancement.

Mobolaji B. Shemfe, Siddharth Gadkari, Jhuma Sadhukhan

Sustainability • 2018

Bioelectrochemical systems (BESs) have been catalogued as a technological solution to three pressing global challenges: environmental pollution, resource scarcity, and freshwater scarcity. This study explores the social risks along the supply chain of requisite components of BESs for two functionalities: (i) copper recovery from spent lees and (ii) formic acid production via CO2 reduction, based on the UK’s trade policy. The methodology employed in this study is based on the UNEP/SETAC guidelines for social life-cycle assessment (S-LCA) of products. Relevant trade data from UN COMTRADE database and generic social data from New Earth’s social hotspot database were compiled for the S-LCA. The results revealed that about 75% of the components are imported from the European Union. However, the social risks were found to vary regardless of the magnitude or country of imports. “Labour and Decent Work” was identified as the most critical impact category across all countries of imports, while the import of copper showed relatively higher risk than other components. The study concludes that BESs are a promising sustainable technology for resource recovery from wastewater. Nevertheless, it is recommended that further research efforts should concentrate on stakeholder engagement in order to fully grasp the potential social risks.

Lixia Zhang, Lizhen Zeng, Jingting Wang et al.

ChemPlusChem • 2024

Abstract Carbon dioxide can be relatively easily reduced to organic matter in a bioelectrochemical system (BES). However, due to insufficient reduction force from in‐situ hydrogen evolution, it is difficult for nitrogen reduction. In this study, MoS 2 was firstly used as an electrocatalyst for the simultaneous reduction of CO 2 and N 2 to produce microbial protein (MP) in a BES. Cell dry weight (CDW) could reach 0.81±0.04 g/L after 14 d operation at −0.7 V (vs. RHE), which was 108±3 % higher than that from non‐catalyst control group (0.39±0.01 g/L). The produced protein had a better amino acid profile in the BES than that in a direct hydrogen system (DHS), particularly for proline (Pro). Besides, MoS 2 promoted the growth of bacterial cell on an electrode and improved the biofilm extracellular electron transfer (EET) by microscopic observation and electrochemical characterization of MoS 2 biocathode. The composition of the microbial community and the relative abundance of functional enzymes revealed that MoS 2 as an electrocatalyst was beneficial for enriching Xanthobacter and enhancing CO 2 and N 2 reduction by electrical energy. These results demonstrated that an efficient strategy to improve MP production of BES is to use MoS 2 as an electrocatalyst to shift amino acid profile and microbial community.

Mahdi Hassan, Guangcan Zhu, Yong-ze LU et al.

Environmental Engineering Research • 2020

In this review, antibiotics are considered an emerging pollutant that has drawn worldwide attention in recent years. Therefore, the effective removal of antibiotic contaminants has become a hot issue in the field of environmental research. Most antibiotics applied to humans eventually enter municipal Wastewater Treatment Plants (WWTPs), because there are no appropriate commercially available pretreatment techniques. However, increasing anthropogenic activities, the high demand for animal-protein in developing countries as a nutritional alternative, and the extensive usage of antibiotics are mainly responsible for the persistence of antibiotic pollutants. One of the serious concerns regarding the presence of antibiotics in water and their potential role in exacerbating the emergence of antibiotics-resistance bacteria (ARB) and antibiotics-resistance genes (ARGs). In recent years, bioelectrochemical technologies are found promising for suppressing antibiotic contaminants through microbial metabolism and electrochemical redox reactions. Therefore, this review provides up-to-date insight research on bioelectrochemical systems (BESs), which improves the removal of the antibiotic in an efficient way. The focus of this review has been on the environmental sources of antibiotics, their health effects and possible degradation pathways, bacterial-antibiotics resistance mechanisms, and treatment of antibiotic-contained water using BES technology.

Sukrampal Yadav, Sunil A. Patil

npj Biofilms and Microbiomes • 2020

Abstract Understanding of the extreme microorganisms that possess extracellular electron transfer (EET) capabilities is pivotal to advance electromicrobiology discipline and to develop niche-specific microbial electrochemistry-driven biotechnologies. Here, we report on the microbial electroactive biofilms (EABs) possessing the outward EET capabilities from a haloalkaline environment of the Lonar lake. We used the electrochemical cultivation approach to enrich haloalkaliphilic EABs under 9.5 pH and 20 g/L salinity conditions. The electrodes controlled at 0.2 V vs. Ag/AgCl yielded the best-performing biofilms in terms of maximum bioelectrocatalytic current densities of 548 ± 23 and 437 ± 17 µA/cm 2 with acetate and lactate substrates, respectively. Electrochemical characterization of biofilms revealed the presence of two putative redox-active moieties with the mean formal potentials of 0.183 and 0.333 V vs. Ag/AgCl, which represent the highest values reported to date for the EABs. 16S-rRNA amplicon sequencing of EABs revealed the dominance of unknown Geoalkalibacter sp. at ~80% abundance. Further investigations on the haloalkaliphilic EABs possessing EET components with high formal potentials might offer interesting research prospects in electromicrobiology.

Soroush Saheb‐Alam, Frank Persson, Britt‐Marie Wilén et al.

Microbial Biotechnology • 2019

Summary In microbial fuel cells ( MFC s), microorganisms generate electrical current by oxidizing organic compounds. MFC s operated with different electron donors harbour different microbial communities, and it is unknown how that affects their response to starvation. We analysed the microbial communities in acetate‐ and glucose‐fed MFC s and compared their responses to 10 days starvation periods. Each starvation period resulted in a 4.2 ± 1.4% reduction in electrical current in the acetate‐fed MFC s and a 10.8 ± 3.9% reduction in the glucose‐fed MFC s. When feed was resumed, the acetate‐fed MFC s recovered immediately, whereas the glucose‐fed MFC s required 1 day to recover. The acetate‐fed bioanodes were dominated by Desulfuromonas spp. converting acetate into electrical current. The glucose‐fed bioanodes were dominated by Trichococcus sp., functioning as a fermenter, and a member of Desulfuromonadales , using the fermentation products to generate electrical current. Suspended biomass and biofilm growing on non‐conductive regions within the MFC s had different community composition than the bioanodes. However, null models showed that homogenizing dispersal of microorganisms within the MFC s affected the community composition, and in the glucose‐fed MFC s, the Trichococcus sp. was abundant in all locations. The different responses to starvation can be explained by the more complex pathway requiring microbial interactions to convert glucose into electrical current.

Dawid Nosek, Agnieszka Cydzik-Kwiatkowska

Energies • 2020

Development of economical and environment-friendly Microbial Fuel Cells (MFCs) technology should be associated with waste management. However, current knowledge regarding microbiological bases of electricity production from complex waste substrates is insufficient. In the following study, microbial composition and electricity generation were investigated in MFCs powered with waste volatile fatty acids (VFAs) from anaerobic digestion of primary sludge. Two anode sizes were tested, resulting in organic loading rates (OLRs) of 69.12 and 36.21 mg chemical oxygen demand (COD)/(g MLSS∙d) in MFC1 and MFC2, respectively. Time of MFC operation affected the microbial structure and the use of waste VFAs promoted microbial diversity. High abundance of Deftia sp. and Methanobacterium sp. characterized start-up period in MFCs. During stable operation, higher OLR in MFC1 favored growth of exoelectrogens from Rhodopseudomonas sp. (13.2%) resulting in a higher and more stable electricity production in comparison with MFC2. At a lower OLR in MFC2, the percentage of exoelectrogens in biomass decreased, while the abundance of genera Leucobacter, Frigoribacterium and Phenylobacterium increased. In turn, this efficiently decomposed complex organic substances, favoring high and stable COD removal (over 85%). Independent of the anode size, Clostridium sp. and exoelectrogens belonging to genera Desulfobulbus and Acinetobacter were abundant in MFCs powered with waste VFAs.

Benjamin Myers, Phil Hill, Frankie Rawson et al.

Johnson Matthey Technology Review • 2022

It is imperative to develop novel processes that rely on cheap, sustainable and abundant resources whilst providing carbon circularity. Microbial electrochemical technologies (MET) offer unique opportunities to facilitate the conversion of chemicals to electrical energy or vice versa by harnessing the metabolic processes of bacteria to valorise a range of waste products including greenhouse gases (GHGs). Part I () introduced the EET pathways, their limitations and applications. Here in Part II, we outline the strategies researchers have used to modulate microbial electron transfer, through synthetic biology and biohybrid approaches and present the conclusions and future directions.

Benjamin Myers, Phil Hill, Frankie Rawson et al.

Johnson Matthey Technology Review • 2022

Traditional microbial synthesis of chemicals and fuels often rely on energy-rich feedstocks such as glucose, raising ethical concerns as they are directly competing with the food supply. Therefore, it is imperative to develop novel processes that rely on cheap, sustainable and abundant resources whilst providing carbon circularity. Microbial electrochemical technologies (MET) offer unique opportunities to facilitate the conversion of chemicals to electrical energy or vice versa , by harnessing the metabolic processes of bacteria to valorise a range of waste products, including greenhouse gases (GHGs). However, the strict growth and nutrient requirements of industrially relevant bacteria, combined with low efficiencies of native extracellular electron transfer (EET) mechanisms, reduce the potential for industrial scalability. In this two-part work, we review the most significant advancements in techniques aimed at improving and modulating the efficiency of microbial EET, giving an objective and balanced view of current controversies surrounding the physiology of microbial electron transfer, alongside the methods used to wire microbial redox centres with the electrodes of bioelectrochemical systems via conductive nanomaterials.