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 • 0

<jats:p>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.</jats:p>

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

Applied Sciences • 0

<jats:p>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.</jats:p>

Alireza Seify, Hassan Ahmadi, Majid Peyravi et al.

Archives of Hygiene Sciences • 2023

<jats:p>Background &amp; 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. </jats:p>

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

Scientific Reports • 0

<jats:title>Abstract</jats:title> <jats:p>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<jats:sub>2</jats:sub>, and MnO<jats:sub>2</jats:sub> 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<jats:sub>2</jats:sub>/MnO<jats:sub>2</jats:sub> 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<jats:sup>’</jats:sup>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.</jats:p>

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

ECS Transactions • 2022

<jats:p>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 &lt;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<jats:sub>m</jats:sub>). Lower α and R<jats:sub>m</jats:sub> 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.</jats:p>

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

Komputika : Jurnal Sistem Komputer • 0

<jats:p>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.</jats:p>

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

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

<jats:p>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.</jats:p>

Sumit Dagar, Santosh Kumar Singh, Manoj Kumar Gupta

Frontiers in Environmental Science • 0

<jats:p>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.</jats:p>

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

TAPPI Journal • 0

<jats:p>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.</jats:p>

Abolghasem Alighardashi, Meghdad Modanlou, Shervin Jamshidi

Water Practice and Technology • 2015

<jats:p>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.</jats:p>

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

Physical Sciences Reviews • 2020

<jats:title>Abstract</jats:title><jats:p>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<jats:sup>3</jats:sup>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.</jats:p>

Matia Mainardis, Silvia Mulloni, Arianna Catenacci et al.

Sustainability • 0

<jats:p>In this work, different alternatives to conventional tertiary treatment of pulp and paper (P&amp;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.</jats:p>

AMANDA JOHANSEN MATTINGLY, PAUL WIEGAND, ROBERT SACKELLARES

TAPPI Journal • 0

<jats:p>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.</jats:p>

Vita HALYSH, Iaroslav RADOVENCHYK, Mykola GOMELYA et al.

Herald of Khmelnytskyi National University. Technical sciences • 2022

<jats:p>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.</jats:p>

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

Chemical Engineering Research Bulletin • 0

<jats:p>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</jats:p>

Anil Dhanda, Akash Tripathi, Rishabh Raj et al.

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

<jats:p>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.</jats:p>

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

Science Advances • 2022

<jats:p>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.</jats:p>

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

Advances in Materials Science and Engineering • 2024

<jats:p>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.</jats:p>

Mobolaji B. Shemfe, Siddharth Gadkari, Jhuma Sadhukhan

Sustainability • 0

<jats:p>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.</jats:p>

Lixia Zhang, Lizhen Zeng, Jingting Wang et al.

ChemPlusChem • 2024

<jats:title>Abstract</jats:title><jats:p>Carbon dioxide can be relatively easily reduced to organic matter in a bioelectrochemical system (BES). However, due to insufficient reduction force from <jats:italic>in‐situ</jats:italic> hydrogen evolution, it is difficult for nitrogen reduction. In this study, MoS<jats:sub>2</jats:sub> was firstly used as an electrocatalyst for the simultaneous reduction of CO<jats:sub>2</jats:sub> and N<jats:sub>2</jats:sub> 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<jats:sub>2</jats:sub> 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<jats:sub>2</jats:sub> biocathode. The composition of the microbial community and the relative abundance of functional enzymes revealed that MoS<jats:sub>2</jats:sub> as an electrocatalyst was beneficial for enriching <jats:italic>Xanthobacter</jats:italic> and enhancing CO<jats:sub>2</jats:sub> and N<jats:sub>2</jats:sub> reduction by electrical energy. These results demonstrated that an efficient strategy to improve MP production of BES is to use MoS<jats:sub>2</jats:sub> as an electrocatalyst to shift amino acid profile and microbial community.</jats:p>

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

Environmental Engineering Research • 0

<jats:p>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.</jats:p>

Sukrampal Yadav, Sunil A. Patil

npj Biofilms and Microbiomes • 0

<jats:title>Abstract</jats:title><jats:p>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<jats:sup>2</jats:sup> 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 <jats:italic>Geoalkalibacter</jats:italic> sp. at ~80% abundance. Further investigations on the haloalkaliphilic EABs possessing EET components with high formal potentials might offer interesting research prospects in electromicrobiology.</jats:p>

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

Microbial Biotechnology • 2019

<jats:title>Summary</jats:title><jats:p>In microbial fuel cells (<jats:styled-content style="fixed-case">MFC</jats:styled-content>s), microorganisms generate electrical current by oxidizing organic compounds. <jats:styled-content style="fixed-case">MFC</jats:styled-content>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 <jats:styled-content style="fixed-case">MFC</jats:styled-content>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 <jats:styled-content style="fixed-case">MFC</jats:styled-content>s and a 10.8 ± 3.9% reduction in the glucose‐fed <jats:styled-content style="fixed-case">MFC</jats:styled-content>s. When feed was resumed, the acetate‐fed <jats:styled-content style="fixed-case">MFC</jats:styled-content>s recovered immediately, whereas the glucose‐fed <jats:styled-content style="fixed-case">MFC</jats:styled-content>s required 1 day to recover. The acetate‐fed bioanodes were dominated by <jats:italic>Desulfuromonas</jats:italic> spp. converting acetate into electrical current. The glucose‐fed bioanodes were dominated by <jats:italic>Trichococcus</jats:italic> sp., functioning as a fermenter, and a member of <jats:italic>Desulfuromonadales</jats:italic>, using the fermentation products to generate electrical current. Suspended biomass and biofilm growing on non‐conductive regions within the <jats:styled-content style="fixed-case">MFC</jats:styled-content>s had different community composition than the bioanodes. However, null models showed that homogenizing dispersal of microorganisms within the <jats:styled-content style="fixed-case">MFC</jats:styled-content>s affected the community composition, and in the glucose‐fed <jats:styled-content style="fixed-case">MFC</jats:styled-content>s, the <jats:italic>Trichococcus</jats:italic> 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.</jats:p>

Dawid Nosek, Agnieszka Cydzik-Kwiatkowska

Energies • 0

<jats:p>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.</jats:p>

Benjamin Myers, Phil Hill, Frankie Rawson et al.

Johnson Matthey Technology Review • 2022

<jats:p>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 <jats:italic>vice versa</jats:italic> 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.</jats:p>

Benjamin Myers, Phil Hill, Frankie Rawson et al.

Johnson Matthey Technology Review • 2022

<jats:p>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 <jats:italic>vice versa</jats:italic>, 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 <jats:italic>via</jats:italic> conductive nanomaterials.</jats:p>

Si Ying Liu, Wipa Charles, Ralf Cord-Ruwisch et al.

Renewable Energy and Environmental Sustainability • 2023

<jats:p>Bioelectrochemical systems (BESs) can be integrated <jats:italic>in situ</jats:italic> into anaerobic digesters for increasing methane (CH<jats:sub>4</jats:sub>) content of biogas. Using BES <jats:italic>ex situ</jats:italic> for improving biogas quality has recently been gaining attention. However, information on the process under thermophilic conditions is very limited. In this study, we placed a BES cathode in-line at the exit gas from a thermophilic anaerobic digester to convert carbon dioxide (CO<jats:sub>2</jats:sub>) in the biogas into CH<jats:sub>4</jats:sub>. The performance of the <jats:italic>ex situ</jats:italic> BES reactor under thermophilic conditions was evaluated. When poising the cathode at −1.1 V versus Ag/AgCl in the <jats:italic>ex situ</jats:italic> BES reactor, CH<jats:sub>4</jats:sub> content increased from 50% to 85%. Of the incoming CO<jats:sub>2</jats:sub> 73% was biologically converted to CH<jats:sub>4</jats:sub> and 23% absorbed by alkalinity generated in the cathode. The energy output as additional CH<jats:sub>4</jats:sub> as a percentage of the energy input to operate the BES was calculated at 56%. The biocathode of the BES reactor was dominated by <jats:italic>Methanothermobacter</jats:italic> spp., which are thermophilic hydrogen consuming methanogens. This study confirms that thermophilic BES can be used as an <jats:italic>ex situ</jats:italic> treatment process for enriching the CH<jats:sub>4</jats:sub> content of biogas. However, energy efficiency of the process was found to be limited by the lack of an energetically efficient anodic reaction. For industrial applications, optimisation of energy efficiency is an area for further research.</jats:p>

Michele Morgante, Nick Vlachopoulos, Anders Hagfeldt et al.

Journal of Physics: Energy • 2021

<jats:title>Abstract</jats:title> <jats:p>In recent years, one of the most important challenges of the 21st century is to satisfy the ever-increasing world’s energy demand. Many efforts are being undertaken to find alternative renewable energy sources, which ideally should outcompete fossil fuel use in all its aspects. In this respect, photo-assisted microbial bioelectrochemical cells (MBECs) in which the reduction of water to hydrogen takes place have been of considerable interest in recent years. Two categories of such systems have been investigated: MBECs with a semiconductor photocathode or photoanode, and hybrid systems, in which an MBEC cell with dark electrodes is coupled to an electrochemical photovoltaic cell. A common denominator of all these systems is the need of microorganisms at the anode, the action of which results in the generation of an electron flow by organic matter oxidation. The aim of this review is to describe the general working principles, with respect to both biochemical and electrochemical aspects, and the performance of various categories of hydrogen-generating photo-assisted MBECs.</jats:p>

Kiran Kuruvinashetti, Hemanth Kumar Tanneru, Pragasen Pillay et al.

Energy Technology • 2021

<jats:sec><jats:label/><jats:p>Biophotoelectrochemical cells are gaining prominence in recent years due to the necessity of sustainable power generation at both micro‐ and macroscale. Toward this direction, microphotosynthetic power cells (μ‐PSC) play a vital role in generating clean energy. The μ‐PSC generates sustainable power under light and in the dark through the photosynthesis and respiration of photosynthetic microorganisms or cells, such as cyanobacteria and green algae. Herein, particulars on μ‐PSCs from fundamentals to real‐time applications are provided. The state of the art of μ‐PSCs, in terms of the principle of operation, design, and materials is presented. μ‐PSCs reported to date are classified based on design, operating parameters, and photosynthetic organisms. In addition, details on the metrics and factors influencing the performance of μ‐PSCs are also discussed. The need for the development of mathematical and electrical equivalent models of μ‐PSCs and the progress in these areas are briefed. Current challenges for μ‐PSCs’ commercialization are identified as high cost and low power densities, and the factors that are leading to low power density and high cost are explored and are also discussed. In addition, the potential solutions to overcome these challenges are investigated.</jats:p></jats:sec>

Anna Espinoza-Tofalos, Matteo Daghio, Enza Palma et al.

Water • 0

<jats:p>Bioelectrochemical systems (BESs) exploit the interaction between microbes and electrodes. A field of application thereof is bioelectrochemical remediation, an effective strategy in environments where the absence of suitable electron acceptors limits classic bioremediation approaches. Understanding the microbial community structure and genetic potential of anode biofilms is of great interest to interpret the mechanisms occurring in BESs. In this study, by using a whole metagenome sequencing approach, taxonomic and functional diversity patterns in the inoculum and on the anodes of three continuous-flow BES for the removal of phenol, toluene, and BTEX were obtained. The genus Geobacter was highly enriched on the anodes and two reconstructed genomes were taxonomically related to the Geobacteraceae family. To functionally characterize the microbial community, the genes coding for the anaerobic degradation of toluene, ethylbenzene, and phenol were selected as genetic markers for the anaerobic degradation of the pollutants. The genes related with direct extracellular electron transfer (EET) were also analyzed. The inoculum carried the genetic baggage for the degradation of aromatics but lacked the capacity of EET while anodic bacterial communities were able to pursue both processes. The metagenomic approach provided useful insights into the ecology and complex functions within hydrocarbon-degrading electrogenic biofilms.</jats:p>

Stefano Freguia, Maddalena Logrieco, Juliette Monetti et al.

Sustainability • 0

<jats:p>Nutrient recovery from source-separated human urine has been identified by many as a viable avenue towards the circular economy of nutrients. Moreover, untreated (and partially treated) urine is the main anthropogenic route of environmental discharge of nutrients, most concerning for nitrogen, whose release has exceeded the planet’s own self-healing capacity. Urine contains all key macronutrients (N, P, and K) and micronutrients (S, Ca, Mg, and trace metals) needed for plant growth and is, therefore, an excellent fertilizer. However, direct reuse is not recommended in modern society due to the presence of active organic molecules and heavy metals in urine. Many systems have been proposed and tested for nutrient recovery from urine, but none so far has reached technological maturity due to usually high power or chemical requirements or the need for advanced process controls. This work is the proof of concept for the world’s first nutrient recovery system that powers itself and does not require any chemicals or process controls. This is a variation of the previously proposed microbial electrochemical Ugold process, where a novel air cathode catalyst active in urine conditions (pH 9, high ammonia) enables in situ generation of electricity in a microbial fuel cell setup, and the simultaneous harvesting of such electricity for the electrodialytic concentration of ionic nutrients into a product stream, which is free of heavy metals. The system was able to sustain electrical current densities around 3 A m–2 for over two months while simultaneously upconcentrating N and K by a factor of 1.5–1.7.</jats:p>

Eole Fukawa, Keisei Sowa, Yuki Kitazumi et al.

ECS Meeting Abstracts • 2024

<jats:p> The interest in the use of redox enzymes for the construction of efficient biodevices has grown to achieve an environmentally friendly society. “Bioelectrocatalysis,” in which enzymatic reaction and electrode reactions are coupled, is a fundamental technology for various electrochemical biomimetics (e.g., biosensors, biofuel cells, and bioreactors). In particular, the reaction in which an enzyme directly shuttles electrons to an electrode without any external electron mediators is called a direct electron transfer (DET)-type reaction. Thanks to its mediator-less configuration, DET-type reaction is advantageous in biocompatibility and design freedom, enabling us to develop ideal bio-devices. However, the number of enzymes performing DET-type reactions (DET-type enzyme) is very limited, which is one of the major problems for developing the aforementioned biodevices. Thus, there has been considerable interest in studies for creating new DET-type enzymes using existing enzymes as templates. To tackle the issue, fundamental research on their catalytic reaction mechanisms is essential.</jats:p> <jats:p>D-Fructose dehydrogenase (FDH) from <jats:italic>Gluconobacter japonicus</jats:italic> NBRC3260, a membrane-bound heterotrimeric flavohemoprotein capable of intense DET-type bioelectrocatalysis, has been widely investigated. FDH forms heterotrimetric structures composed of the catalytic large subunit, the chaperonic small subunit, and the membrane-bound cytochrome <jats:italic>c</jats:italic> subunit. Although the catalytic center is flavin adenine dinucleotide (FAD), the details for substrate oxidation remain unclear. Thanks to its extremely high DET-type activity and its covalently-bound cofactors, FDH is regarded as the model DET-type enzyme. Several researchers have already revealed the enzyme properties, focusing on DET from the viewpoints of enzyme engineering and electrochemistry. In addition, the three-dimensional (3D) structure of FDH was first revealed in 2022 with cryo-electron microscopy (cryo-EM) analysis, enabling us to discuss the enzyme from the perspective of structural biology and bioinformatics. In this study, we intend to understand the catalytic mechanism of FDH, such as substrate recognition or catalysis.</jats:p> <jats:p>First, we performed enzyme-substrate docking simulation and homology search to estimate critical amino acid residues in the catalytic reaction. These results indicated that three amino acid residues around FAD (N1146, H1147, and N1190) were the critical residues. Site-directed FDH variants focused on the residues (Namely, N1146A, N1146Q, H1147A, and N1190A) were expressed, purified, and evaluated.</jats:p> <jats:p>Next, the electrochemical properties of variants were evaluated with enzyme-modified rotating disk electrodes at 2000 rpm, pH 4.5, and 25 °C. From the cyclic voltammogram, we found that the mutations to H1147 or N1190 brought remarkable declines in DET-type activities, implying the importance of the two residues for the catalytic reaction. Substrate concentration dependence of the variants on the catalytic currents (Michaelis-Menten plot) revealed that the mutation into N1146 or H1147 resulted in increases in Michaelis constants, which indicates that the two residues seemed to have roles in fructose recognition. Because the two N1146 variants (N1146A or N1146Q) maintained sufficient activities, we examined substrate characteristics for various sugars and confirmed that the relative activity of N1146Q with D-tagatose, the C4 epimer of D-fructose, was improved over that of recombinant FDH.</jats:p> <jats:p>Finally, we also discuss the properties of variants from structural biology. The structures of the variants were successfully analyzed with cryo-EM analysis, and the N1146A, N1146Q, H1147A, and N1190A resolutions were 2.4, 3.1, 2.8, and 3.0 Å, respectively. The overall quaternary structures remained almost unchanged, indicating that each point mutation did not disrupt the protein structure. The direction and position of the amino acid residues of each variant differed slightly around the mutation sites. When using their structure for enzyme-substrate docking simulation, a good relationship between docking scores and Michaelis constants of the variants was observed. This means that the decline in the affinity between the variants and the substrate can be explained in structural biology. In the simulation, on the other hand, we obtained different results when using <jats:italic>in-silico</jats:italic> variants (computationally constructed), implying room for improvement in the current protein structure prediction methods.</jats:p> <jats:p>In summary, we investigated the mechanisms underlying the catalytic activity of FDH using enzyme engineering, electrochemistry, structural biology, and bioinformatics. H1147 and N1190 are particularly important for catalytic activity, with H1147 mainly functioning as a basic catalyst. N1146, H1147, and N1190 contribute to the recognition of the fructose molecules. In the future, our understanding of the fundamental reaction mechanism is expected to lead to the computational design and creation of various DET-type enzymes with FDH as a template. </jats:p>

A. Carucci, G. Erby, G. Puggioni et al.

Water Science and Technology • 2022

<jats:title>Abstract</jats:title> <jats:p>Growing food and biomass production at the global scale has determined a corresponding increase in the demand for and use of nutrients. In this study, the possibility of recovering nitrogen from agro-industrial digestate using bioelectrochemical systems was investigated: two microbial electrolysis cells (MECs) were fed with synthetic and real digestate (2.5 gNH4+-N L−1). Carbon felt and granular graphite were used as anodes in MEC-1 and MEC-2, respectively. As to synthetic wastewater, the optimal nitrogen load (NL) for MEC-1 and -2 was 1.25 and 0.75 gNH4+-N d−1, respectively. MEC-1 showed better performance in terms of NH4+-N removal efficiency (39 ± 2.5%) and recovery rate (up to 70 gNH4+-N m−2d−1), compared to MEC-2 (33 ± 4.7% and up to 30 gN m−2d−1, respectively). At the optimal hydraulic retention time, lower NH4+-N removal efficiencies and recovery rates were observed when real digestate was fed to MEC-1 (29 ± 6.6% and 60 ± 13 gNH4+-N m−2d−1, respectively) and MEC-2 (21 ± 7.9% and 10 ± 3.6 gNH4+-N m−2d−1, respectively), likely due to the higher complexity of the influent. The average energy requirements were 3.6–3.7 kWh kgNremoved−1, comparable with values previously reported in the literature and lower than conventional ammonia recovery processes. Results are promising and may reduce the need for costly and polluting processes for nitrogen synthesis.</jats:p>

Marco Zeppilli, Edoardo Dell’Armi, Lorenzo Cristiani et al.

Water • 0

<jats:p>An innovative bioelectrochemical reductive/oxidative sequential process was developed and tested on a laboratory scale to obtain the complete mineralization of perchloroethylene (PCE) in a synthetic medium. The sequential bioelectrochemical process consisted of two separate tubular bioelectrochemical reactors that adopted a novel reactor configuration, avoiding the use of an ion exchange membrane to separate the anodic and cathodic chamber and reducing the cost of the reactor. In the reductive reactor, a dechlorinating mixed inoculum received reducing power to perform the reductive dechlorination of perchloroethylene (PCE) through a cathode chamber, while the less chlorinated daughter products were removed in the oxidative reactor, which supported an aerobic dechlorinating culture through in situ electrochemical oxygen evolution. Preliminary fluid dynamics and electrochemical tests were performed to characterize both the reductive and oxidative reactors, which were electrically independent of each other, with each having its own counterelectrode. The first continuous-flow potentiostatic run with the reductive reactor (polarized at −450 mV vs SHE) resulted in obtaining 100% ± 1% removal efficiency of the influent PCE, while the oxidative reactor (polarized at +1.4 V vs SHE) oxidized the vinyl chloride and ethylene from the reductive reactor, with removal efficiencies of 100% ± 2% and 92% ± 1%, respectively.</jats:p>

Miriam Edel, Laura-Alina Philipp, Jonas Lapp et al.

Extremophiles • 2022

<jats:title>Abstract</jats:title><jats:p>The interaction of bacteria and archaea with electrodes is a relatively new research field which spans from fundamental to applied research and influences interdisciplinary research in the fields of microbiology, biochemistry, biotechnology as well as process engineering. Although a substantial understanding of electron transfer processes between microbes and anodes and between microbes and cathodes has been achieved in mesophilic organisms, the mechanisms used by microbes under extremophilic conditions are still in the early stages of discovery. Here, we review our current knowledge on the biochemical solutions that evolved for the interaction of extremophilic organisms with electrodes. To this end, the available knowledge on pure cultures of extremophilic microorganisms has been compiled and the study has been extended with the help of bioinformatic analyses on the potential distribution of different electron transfer mechanisms in extremophilic microorganisms.</jats:p>

Jungho Jang, Byoung Wook Jeon, Yong Hwan Kim

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>The conversion of carbon dioxide to formate is a fundamental step for building C1 chemical platforms. <jats:italic>Methylobacterium extorquens</jats:italic> AM1 was reported to show remarkable activity converting carbon dioxide into formate. Formate dehydrogenase 1 from <jats:italic>M. extorquens</jats:italic> AM1 (MeFDH1) was verified as the key responsible enzyme for the conversion of carbon dioxide to formate in this study. Using a 2% methanol concentration for induction, microbial harboring the recombinant MeFDH1 expressing plasmid produced the highest concentration of formate (26.6 mM within 21 hours) in electrochemical reactor. 60 μM of sodium tungstate in the culture medium was optimal for the expression of recombinant MeFDH1 and production of formate (25.7 mM within 21 hours). The recombinant MeFDH1 expressing cells showed maximum formate productivity of 2.53 mM/g-wet cell/hr, which was 2.5 times greater than that of wild type. Thus, <jats:italic>M. extorquens</jats:italic> AM1 was successfully engineered by expressing MeFDH1 as recombinant enzyme to elevate the production of formate from CO<jats:sub>2</jats:sub> after elucidating key responsible enzyme for the conversion of CO<jats:sub>2</jats:sub> to formate.</jats:p>

Nhlanganiso Ivan Madondo, Emmanuel Kweinor Tetteh, Sudesh Rathilal et al.

Bioengineering • 0

<jats:p>Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.</jats:p>

Daniele Cecconet, Silvia Bolognesi, Luca Piacentini et al.

Water • 0

<jats:p>Greywater normally represents the largest fraction of wastewater generated in buildings and may be suitable for non-potable reuse after on-site treatment. Conventional technologies for greywater treatment include sequencing batch reactors, membrane filtration, and membrane biological reactors. Even though these can be very effective, they are highly energy consuming and may negatively impact the energy balance of the building where they are installed. Microbial fuel cells (MFCs) have emerged as a sustainable technology for contaminant removal and energy production from a variety of substrates. In this study, the application of MFCs for greywater treatment is reported, with a particular focus on the analysis of energy losses, in view of non-potable reuse. MFCs were fed with different types of greywater, characterized by either high or low conductivity, because greywater’s conductivity may greatly differ based on its origin; in either case, organic matter (chemical oxygen demand; COD) removal was higher than 85% and not influenced by the influent conductivity, coupled with a maximum power production of 0.46 mW L−1 and 0.38 mW L−1. Electrolyte overpotentials were dramatically higher in the case of low conductivity greywater (20% vs. 10%, compared to high conductivity influent); these overpotentials are related to the conductivity of the influent, showing that low conductivity hindered energy generation, but not COD removal. Polarization and power curves showed higher internal resistance in the case of low conductivity, confirming the overpotentials’ analysis. Results showed the feasibility of the use of MFCs in greywater treatment, with potential to reduce the energy demand connected to its reuse compared to conventional technologies; coupling with a disinfection stage would be necessary to fully comply with most non-potable reuse regulations.</jats:p>