Degradation of 2-mercaptobenzothizaole in microbial electrolysis cells: Intermediates, toxicity, and microbial communities

Degradation of sulfamethazine by microbial electrolysis cell with nickel-cobalt co-modified biocathode

In this study, nickel-cobalt co-modified stainless steel mesh (Ni-Co@SSM) was prepared and used as the biocathode in microbial electrolysis cell (MEC) for sulfamethazine (SMT) degradation. The optimal electrochemical performance of the Ni-Co@SSM was obtained at the electrodeposition time of 600 s, electrodeposition current density of 20 mA cm-2, and nickel-cobalt molar ratio of 1:2. The removal of SMT in MEC with the Ni-Co@SSM biocathode (MEC-Ni-Co@SSM) was 82%, which increased by 30% compared with the conventional anaerobic reactor. Thirteen intermediates were identified and the potential degradation pathways of SMT were proposed. Proteobacteria, Firmicutes, Patescibacteria, Chloroflexi, Bacteroidetes, and Euryarchaeota are the dominant bacteria at the phylum level in the MEC-Ni-Co@SSM, which are responsible for SMT metabolism. Due to the electrical stimulation, there was an increase in the abundance of the metabolic function and the genetic information processing. This work provides valuable insight into utilizing MECs for effective treatment of antibiotic-containing wastewater.

Environmental biotechnology and the involving biological process using graphene-based biocompatible material

Biotechnology is a promising approach to environmental remediation but requires improvement in efficiency and convenience. The improvement of biotechnology has been illustrated with the help of biocompatible materials as biocarrier for environmental remediations. Recently, graphene-based materials (GBMs) have become promising materials in environmental biotechnology. To better illustrate the principle and mechanisms of GBM application in biotechnology, the comprehension of the biological response of microorganisms and enzymes when facing the GBMs is needed. The review illustrated distinct GBM-microbe/enzyme composites by providing the GBM-microbe/enzyme interaction and the determining factors. There are diverse GBM modifications for distinct biotechnology applications. Each of these methods and applications depends on the physicochemical properties of GBMs. The applications of these composites were mainly categorized as pollutant adsorption, anaerobic digestion, microbial fuel cells, and organics degradation. Where information was available, the strategies and mechanisms of GBMs in improving application efficacies were also demonstrated. In addition, the biological response, from microbial community changes, extracellular polymeric substances changes to biological pathway alteration, may become important in the application of these composites. Furthermore, we also discuss challenges facing the environmental application of GBMs, considering their fate and toxicity in the ecosystem, and offer potential solutions. This research significantly enhances our comprehension of the fundamental principles, underlying mechanisms, and biological pathways for the in-situ utilization of GBMs.

Carbon Fibers for Bioelectrochemical: Precursors, Bioelectrochemical System, and Biosensors

Abstract

Carbon fibers (CFs) demonstrate a range of excellent properties including (but not limited to) microscale diameter, high hardness, high strength, light weight, high chemical resistance, and high temperature resistance. Therefore, it is necessary to summarize the application market of CFs. CFs with good physical and chemical properties stand out among many materials. It is believed that highly fibrotic CFs will play a crucial role. This review first introduces the precursors of CFs, such as polyacrylonitrile, bitumen, and lignin. Then this review introduces CFs used in BESs, such as electrode materials and modification strategies of MFC, MEC, MDC, and other cells in a large space. Then, CFs in biosensors including enzyme sensor, DNA sensor, immune sensor and implantable sensor are summarized. Finally, we discuss briefly the challenges and research directions of CFs application in BESs, biosensors and more fields.

Highlights

CF is a new-generation reinforced fiber with high hardness and strength.Summary precursors from different sources of CFs and their preparation processes.Introduction of the application and modification methods of CFs in BESs and biosensor.Suggest the challenges in the application of CFs in the field of bio-electrochemistry.Propose the prospective research directions for CFs.

Graphical abstract

Integration of microbial electrochemical systems and photocatalysis for sustainable treatment of organic recalcitrant wastewaters: Main mechanisms, recent advances, and present prospects

In recent years, microbial electrochemical systems (MESs) have demonstrated to be an environmentally friendly technology for wastewater treatment and simultaneous production of value-added products or energy. However, practical applications of MESs for the treatment of recalcitrant wastewater are limited by their low power output and slow rates of pollutant biodegradation. As a novel technology, hybrid MESs integrating biodegradation and photocatalysis have shown great potential to accelerate the degradation of bio-recalcitrant pollutants and increase the system output. In this review, we summarize recent advances of photo-assisted MESs for enhanced removal of recalcitrant pollutants, and present further discussion about the synergistic effect of biodegradation and photocatalysis. In addition, we analyse in detail different set-up configurations, discuss mechanisms of photo-enhanced extracellular electron transfer, and briefly present ongoing research cases. Finally, we highlight the current limitations and corresponding research gaps, and propose insights for future research.

Efficient degradation of various emerging pollutants by wild type and evolved fungal DyP4 peroxidases

The accumulation of emerging pollutants in the environment remains a major concern as evidenced by the increasing number of reports citing their potential risk on environment and health. Hence, removal strategies of such pollutants remain an active area of investigation. One way through which emerging pollutants can be eliminated from the environment is by enzyme-mediated bioremediation. Enzyme-based degradation can be further enhanced via advanced protein engineering approaches. In the present study a sensitive and robust bioanalytical liquid chromatography-tandem mass spectrometry (LCMSMS)-based approach was used to investigate the ability of a fungal dye decolorizing peroxidase 4 (DyP4) and two of its evolved variants—that were previously shown to be H₂O₂ tolerant—to degrade a panel of 15 different emerging pollutants. Additionally, the role of a redox mediator was examined in these enzymatic degradation reactions. Our results show that three emerging pollutants (2-mercaptobenzothiazole (MBT), paracetamol, and furosemide) were efficiently degraded by DyP4. Addition of the redox mediator had a synergistic effect as it enabled complete degradation of three more emerging pollutants (methyl paraben, sulfamethoxazole and salicylic acid) and dramatically reduced the time needed for the complete degradation of MBT, paracetamol, and furosemide. Further investigation was carried out using pure MBT to study its degradation by DyP4. Five potential transformation products were generated during the enzymatic degradation of MBT, which were previously reported to be produced during different bioremediation approaches. The current study provides the first instance of the application of fungal DyP4 peroxidases in bioremediation of emerging pollutants.

A review of recent advances in electrode materials for emerging bioelectrochemical systems: From biofilm-bearing anodes to specialized cathodes

Bioelectrochemical systems (BES), mainly microbial fuel cells (MEC) and microbial electrolysis cells (MFC), are unique biosystems that use electroactive bacteria (EAB) to produce electrons in the form of electric energy for different applications. BES have attracted increasing attention as a sustainable, low-cost, and neutral-carbon option for energy production, wastewater treatment, and biosynthesis. Complex interactions between EAB and the electrode materials play a crucial role in system performance and scalability. The electron transfer processes from the EAB to the anode surface or from the cathode surface to the EAB have been the object of numerous investigations in BES, and the development of new materials to maximize energy production and overall performance has been a hot topic in the last years. The present review paper discusses the advances on innovative electrode materials for emerging BES, which include MEC coupled to anaerobic digestion (MEC-AD), Microbial Desalination Cells (MDC), plant-MFC (P-MFC), constructed wetlands-MFC (CW-MFC), and microbial electro-Fenton (BEF). Detailed insights on innovative electrode modification strategies to improve the electrode transfer kinetics on each emerging BES are provided. The effect of materials on microbial population is also discussed in this review. Furthermore, the challenges and opportunities for materials scientists and engineers working in BES are presented at the end of this work aiming at scaling up and industrialization of such versatile systems.

Role of bioelectrochemical systems for the remediation of emerging contaminants from wastewater: A review

Bioelectrochemical systems (BESs) are a unique group of wastewater remediating technology that possesses the added advantage of valuable recovery with concomitant wastewater treatment. Moreover, due to the application of robust microbial biocatalysts in BESs, effective removal of emerging contaminants (ECs) can be accomplished in these BESs. Thus, this review emphasizes the recent demonstrations pertaining to the removal of complex organic pollutants of emerging concern present in wastewater through BES. Owing to the recalcitrant nature of these pollutants, they are not effectively removed through conventional wastewater treatment systems and thereby are discharged into the environment without proper treatment. Application of BES in terms of ECs removal and degradation mechanism along with valuables that can be recovered are discussed. Moreover, the factors affecting the performance of BES, like biocatalyst, substrate, salinity, and applied potential are also summarized. In addition, the present review also elucidates the occurrence and toxic nature of ECs as well as future recommendations pertaining to the commercialization of this BES technology for the removal of ECs from wastewater. Therefore, the present review intends to aid the researchers in developing more efficient BESs for the removal of ECs from wastewater.

Efficient Degradation of 2-Mercaptobenzothiazole and Other Emerging Pollutants by Recombinant Bacterial Dye-Decolorizing Peroxidases

In recent years, concerns are being raised about the potential harmful effects of emerging pollutants (EPs) on human and aquatic lives. Extensive research is being conducted on developing efficient remediation strategies to target this new class of toxic pollutants. Studies focused on biological (enzyme-based) methods have shown potential as greener and possibly more economical alternatives to other treatment approaches, such as chemical methods. The current study focused on the use of recombinantly produced novel bacterial peroxidases, namely dye-decolorizing peroxidases (DyPs), to study their effectiveness in degrading a number of diverse EPs. In this context, a sensitive bioanalytical Liquid chromatography-tandem mass spectrometry (LCMSMS)-based method was developed to simultaneously detect a mixture of 31 EPs and to examine their degradability by a panel of seven different recombinant bacterial DyPs (rDyPs). We show that up to 9 of the 31 tested EPs could be degraded by at least one of the DyPs tested. The results also indicated that not all rDyPs behaved similarly in their abilities to degrade EPs, as some rDyPs (such as SviDyP and CboDyP) showed a promising potential to degrade EPs while others (such as ScDyP) were almost ineffective. Additionally, the role of redox mediators for effective emerging pollutant degradation by rDyPs was also examined, which showed dramatic improvement in the DyP-mediated degradation of five different EPs. Detailed analysis of 2-mercaptobenzothiazole degradation by SviDyP showed that six distinct breakdown products were generated. The present study showed for the first time that recombinant bacterial DyPs can be used for wastewater remediation by degrading a range of different EPs.

Recent progress in environmentally friendly bio-electrochemical devices for simultaneous water desalination and wastewater treatment

Bio-electrochemical systems (BESs) use electroactive micro-organisms for degrading organic materials in wastes for energy and/or chemical production. Microbial based desalination system is a cost-effective and environmentally friendly technique that can be used for water desalination with simultaneous wastewater treatment and energy harvesting. These systems can be used as a standalone technology for water desalination such as microbial desalination cell, microbial electrolysis desalination cell, or a hybrid with other desalination technology. This review summarized the recent progress in using BESs for water desalination, including microbial fuel cell-based desalination (MDC) and microbial electrolysis cell-based desalination (MEDC). The different scaling up trials to commercialize this technology, including the controlling parameters, are discussed. Moreover, the different hybrid desalination systems based on BES are summarized. Finally, the challenges facing the commercialization of the MDC systems were summarized.

Enrichment and characterization of bacterial consortia for degrading 2-mercaptobenzothiazole in rubber industrial wastewater

Benzothiazoles especially 2-mercaptobenzothiazole (2-MBT) in rubber industrial wastewater can be released into the environment. They can cause adverse health impacts. This study aimed to obtain efficient 2-MBT-degrading bacteria for wastewater application. The bacterial consortia were enriched by incubating rubber wastewater sludge in a medium containing 2-MBT for 28 days. Stepwise acclimatization was conducted with increasing 2-MBT concentrations from 50 to 200 mg L^-1 in nitrogen-containing medium for 76 days. The process significantly increased the bacterial number and changed the dominant populations. Among these consortia, the EN consortium from benzothiazole-containing sludge had the highest specific 2-MBT biodegradation rate of 5.2 ± 0.5 mg L^-1 day^-1 mg protein^-1 and could degrade up to 300 mg L^-1 2-MBT. From 16S rRNA gene analysis, Pseudomonas was the dominant genus at approximately 70 % of the total population. Stenotrophomonas was the second most abundant populations and have never been reported for 2-MBT biodegradation. The EN consortium removed 65-79 % and 90-93 % of 112 mg L^-1 2-MBT and ∼4000 mg L^-1 COD in rubber wastewater, respectively, which were significantly higher than the values of natural attenuation. Therefore, the EN consortium could be an ideal inoculum for the post-treatment of benzothiazoles in rubber industrial wastewater.