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Microbial electrolysis cells (MECs) are a new bio-electrochemical method for converting organic matter to hydrogen gas (H2). Palm oil mill effluent (POME) is hazardous wastewater that is mostly formed during the crude oil extraction process in the palm oil industry. In the present study, POME was used in the MEC system for hydrogen generation as a feasible treatment technology. To enhance biohydrogen generation from POME in the MEC, an empirical model was generated using response surface methodology (RSM). A central composite design (CCD) was utilized to perform twenty experimental runs of MEC given three important variables, namely incubation temperature, initial pH, and influent dilution rate. Experimental results from CCD showed that an average value of 1.16 m3 H2/m3 d for maximum hydrogen production rate (HPR) was produced. A second-order polynomial model was adjusted to the experimental results from CCD. The regression model showed that the quadratic term of all variables tested had a highly significant effect (P

Pharmaceutical wastewaters presently remain as one of the primary roots of environmental pollution. The current study mainly concentrated on removing cefazolin (CEZ) from pharmaceutical wastewater employing the electrocoagulation (EC) process using iron electrodes. The EC experimental conditions were achieved by using response surface methodology (RSM) with an efficiency of 85.65% under optimal working conditions of pH = 8.0, current density (16 mA/cm2), initial CEZ concentration (25 mg/L), and inter-electrode distance (d = 1.0 cm) at an equilibrium electrolysis time of 40 min. The experimental results obtained were in good agreement with the predicted CEZ removal efficiency of 86.7%. Besides, Analysis of variance (ANOVA) revealed that the experimental model was best suited to a second-order polynomial equation, with an R2 value of 0.92. Moreover, the fisher's F-value of 13.67 and low probability value (p

The discharge of phosphorus from urban and industrial wastewater into water bodies causes eutrophication and algae blooms. What it seems essential is that treatment of such wastewater before its di...

Bioelectrochemical systems (BES) have the potential to be used in a variety of applications such as waste biorefinery, pollutants removal, CO

© 2022 The AuthorsThe rapidly expanding global energy demand is forcing a release of regulated pollutants into water that is threatening human health. Among various wastewater remediating processes, electrocoagulation (EC) has scored a monumental success over conventional processes because it combines coagulation, sedimentation, floatation and electrochemical oxidation processes that can effectively decimate numerous stubborn pollutants. The EC processes have gained some attention through various academic and industrial publications, however critical evaluation of EC processes, choices of EC processes for various pollutants, process parameters, mechanisms, commercial EC technologies and performance enhancement via other degradation processes (DPs) integration have not been comprehensively covered to date. Therefore, the major objective of this paper is to provide a comprehensive review of 20 years of literature covering EC fundamentals, key process factors for a reactor design, process implementation, current challenges and performance enhancement by coupling EC with pivotal pollutant DPs including, electro/photo-Fenton (E/P–F), photocatalysis, sono-chemical treatment, ozonation, indirect electrochemical/advanced oxidation (AO), and biosorption that have substantially reduced metals, pathogens, toxic compound BOD, COD, colors in wastewater. The results suggest that the optimum treatment time, current density, pulse frequency, shaking speed and spaced electrode improve the pollutants removal efficiency. An elegant process design can prevent electrode passivation which is a critical limitation of EC technology. EC coupling (up or downstream) with other DPs has resulted in the removal of organic pollutants and heavy metals with a 20% improved efficiency by EC-EF, removal of 85.5% suspended solid, 76.2% turbidity, 88.9% BOD, 79.7% COD and 93% color by EC-electroflotation, 100% decolorization by EC-electrochemical-AO, reduction of 78% COD, 81% BOD, 97% color by EC-ozonation and removal of 94% ammonia, 94% BOD, 95% turbidity, >98% phosphorus by aerated EC and peroxicoagulation. The major wastewater purification achievements, future potential and challenges are described to model the future EC integrated systems.

The continual discharge of emerging inorganic pollutants into natural aquatic systems and their negative effects on the environment have motivated the researchers to explore and develop clean and efficient water treatment strategies. Electrocoagulation (EC) is a rapid and promising pollutant removal approach that does not require any chemical additives or complicated process management. Therefore, inorganic pollutant treatment via the EC process is considered one of the most feasible processes. The potential developments of EC process may make the process a wise choice for water treatment in the future. Thus, the present study mainly focuses on the use of EC technology to remove nutrients and other emerging inorganic pollutants from water medium. The operating factors that influence EC process efficiency are explained. The major advancement of the EC technique as well as field-implemented units are also discussed. Overall, this study mainly focuses on emerging issues, present advancements, and techno-economic considerations in EC process.

Electrocoagulation (EC) is an excellent and promising technology in wastewater treatment, as it combines the benefits of coagulation, flotation, and electrochemistry. During the last decade, extensive researches have focused on removal of emerging contaminants by using electrocoagualtion, due to its several advantages like compactness, cost-effectiveness, efficiency, low sludge production, and eco-friendness. Emerging contaminants (ECs) are micropollutants found in trace amounts that discharging into conventional wastewater treatment (WWT) plants entering surface waters and imposing a high threat to human and aquatic life. Various studies reveal that about 90% of emerging contaminants are disposed unscientifically into water bodies, creating problems to public health and environment. The studies on removal of emerging contaminants from wastewater are by global researchers are critically reviewed. The core findings proved that still more research required into optimization of parameters, system design, and economic feasibility to explore the potential of EC combined systems. This review has introduced an innovative collection of current knowledge on electro-coagulation for the removal of emerging contaminants.

Pharmaceutical wastewater is a frequent kind of wastewater with high quantities of organic pollutants, although little research has been done in the area. Pharmaceutical wastewaters containing antibiotics and high salinity may impair traditional biological treatment, resulting in the propagation of antibiotic resistance genes. The potential for advanced oxidation processes (AOPs) to break down hazardous substances instead of present techniques that essentially transfer contaminants from wastewater to sludge, a membrane filter, or an adsorbent has attracted interest. Among a variety of AOPs, electrochemical systems are a feasible choice for treating pharmaceutical wastewater. Many electrochemical approaches exist now to remediate rivers polluted by refractory organic contaminants, like pharmaceutical micro-pollutants, which have become a severe environmental problem. The first part of this investigation provides the bibliometric analysis of the title search from 1970 to 2021 for keywords such as wastewater and electrochemical. We have provided information on relations between keywords, countries, and journals based on three fields plot, inter-country co-authorship network analysis, and co-occurrence network visualization. The second part introduces electrochemical water treatment approaches customized to these very distinct discarded flows, containing how processes, electrode materials, and operating conditions influence the results (with selective highlighting cathode reduction and anodic oxidation). This section looks at how electrochemistry may be utilized with typical treatment approaches to improve the integrated system's overall efficiency. We discuss how electrochemical cells might be beneficial and what compromises to consider when putting them into practice. We wrap up our analysis with a discussion of known technical obstacles and suggestions for further research.

As a renewable energy carrier, hydrogen gains international recognition, with the ability to substitute fossil fuels. A state-of-the-art technology called a microbial electrolysis cell (MEC) can produce viable, clean hydrogen energy and also treat wastewater using various renewable carbon sources. The key substrates tested include wastewater, fermentable, and nonfermentable organic effluents. This chapter mainly discuss the scientific fundamentals of MEC technology, including its operating principles, thermodynamics, and electron transfer mechanisms. This chapter also discusses the nutrient, heavy metal removal, and integrated technologies used for higher hydrogen production.

In a comparative approach toward treating real pulp and paper wastewater (PPWW), iron-based electro-chemical processes such as peroxi-coagulation (PC), electrocoagulation (EC), electro-Fenton (EF), and ultrasound-assisted PC, EC, and EF were investigated. Sono-peroxi-coagulation (SPC) process showed the best performance for treating the PPWW. The optimal results were achieved under reaction time 50 min, current density 140 mA, and pH = 2.0. Employing the SPC process for treating PPWW under optimal conditions, the best COD removal efficiency (81.7%) was achieved. Also, continuous pH adjustment of the solution, as compared to lack of adjustment, showed a significant influence on COD removal efficiency (more than 10%). The effect of pH on the SPC process and the kind of electro-chemical treatment process utilized, on biodegradability were investigated using BOD/COD ratio and average oxidation state (AOS). In comparison with other electro-chemical processes used in this study, the best biodegradability results were obtained for the SPC process in pH = 2, being 0.4 and 0.94 for BOD/COD ratio and AOS, respectively. SPC process compared to the sono EF process had superior COD removal efficiency and their difference in performance reached near 40%. The influence of sonication was obtained 11.3% and 9% for PC and EF processes respectively. In evaluating the toxicity, the best germination index of Raphanus sativus, irrigated by treated wastewater samples, was achieved 77.9% for the SPC process. The application of US for electrochemical process increased energy consumption and cost of process considerably. The sludge of SPC was also evaluated by Fourier transform infrared spectrum (FTIR), X-ray diffractometer (XRD) and field emission scanning electron microscope (FESEM).

This review focuses on the current developments and new insights in the field of dark fermentation technologies using wastewater as carbon and nutrient source. It has begun with the type of wastewaters (sugar rich, toxic and industrial) employed in the H 2 production and their production performances with pure (or) mixed microbiota as seeding source in the batch reactors. Secondly, well-documented continuous system performances and their failure reasons were examined along with the enhancement possibilities in ways of strategies. A SWOT analysis has been performed to validate the strength and weakness of the continuous systems towards its industrialization and possible scheme of the integration methods have been illustrated. Additionally, an outlook has been provided with enlightening the remedies for its success. Moreover, the practical perspectives of the continuous systems are highlighted and challenges towards scale up are mentioned. Finally, the possible integrative approaches along with continuous systems towards the bioH 2 technologies implementation are enlightened.

Microbial electrolysis cell (MEC) is a promising technology for simultaneous wastewater treatment and bioenergy generation (H2). The mixture of organic compounds present in wastewater acts as the source of free electron in the MECs. H2 production rate and yield by conventional methods including dark fermentation, photo-fermentation and biophotolysis are reported to be lower due to thermodynamic barrier. This thermodynamic barrier can be overcome by applying a small input of electrical energy in an MEC. MECs are not only capable of producing H2 production from wastewater, but it could also be utilized to recover value-added biochemicals or fuels from wastewater via the various integrated process. The present chapter reviews the current applications of MECs in H2 production, wastewater treatment and other value added chemical production along with the advantages of MECs over conventional technologies.

Microbial electrolysis cell (MEC) is a promising and relatively newer bioelectrochemical process for sustainable H2, value-added compounds production, and simultaneous wastewater treatment. As compared to other alternative technologies, the MEC has shown numerous strengths: primarily, the MECs pledge the feasibility to generate H2 at proportionately less energy consumption than the usual energy demand for water electrolysis. In addition, MECs are not restricted by dark fermentation (DF) barriers; H2 could be completely extracted from the spent medium in MECs, achieving remarkable H2 recovery than all kinds of processes. What is more, significantly pure H2 is generated in the MECs cathodes. Besides, MECs incorporate both treatment of waste and bioenergy generation, thereby the MEC possesses the benefits of being environmentally friendly, efficient, and waste disposal. Also, MEC has the ability to produce a wide variety of value-added products, such as methane, hydrogen peroxide, ethanol, and so on, and all these attracted enormous attention in both academia and industry. The MEC must be robust enough to be used in the field for bioremediation or energy production.

A two-chambered microbial fuel cell (MFC), which can function on the self-driven bioelectrogenic activity operated on anaerobically digested distillery waste (ADDW) i.e. wastewater post anaerobic digestion was designed and fabricated in the laboratory. MFC was evaluated for production of bioelectricity with a simultaneous reduction in the carbon content. Using a surface response methodology with a Box-Behnken design (BBD), operating conditions such as the concentration of antifoam, pH, and resistance were optimized and it was found that the pH and resistance were optimum at 8.3 and 1000 0, respectively with no antifoam in the system. Under optimum conditions, 31.49 Wm-3 was generated, and 60.78 +/- 0.95% total organic carbon was degraded. We revealed that the fermentative bacteria generated organic acids mainly acetate from dextrose present in ADDW and electrogenic bacteria oxidized acetate in a successive manner to generate electrons, which was confirmed by gas chromatography. The development of biofilm analyzed by scanning electron microscope (SEM) was found to be crucial in the transfer of electrons directly to the anode and was confirmed by cyclic voltammetry experiments. Identification of bacteria from biofilm by both culture and denaturing gradient gel electrophoresis methods found bacteria belonging to phylum Firmicutes and gamma-proteobacteria. The study of successive nature of bacterial metabolism to generate electricity could play an important role in the production of electricity in a continuous mode of operation using MFCs fed with ADDW for further reduction of carbon content post anaerobic digestion for the benefit for the environment. Thus MFC can be used as a complementary technology to anaerobic digestion. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Microbial electrochemical systems (MESs) are an attracting technology for the disposal of wastewater treatment and simultaneous energy production. In MESs, at the anode microorganisms through the catalytic activity generates electrons that can be converted into electricity or other valuable chemical compounds. Microorganisms those having ability to donate and accept electrons to and from anode and cathode electrodes, respectively are recognized as 'exoelectrogens'. In the MESs, it renders an important function for its performance. In the present mini-review, we have discussed the role of microbiome including pure culture, enriched culture and mixed culture in different BESs application. The effects of operational and biological factors on microbiome development have been discussed. Further discussion about the molecular techniques for the evaluation of microbial community analysis is addressed. In addition different electrochemical techniques for extracellular electron transfer (EET) mechanism of electroactive biofilms have been discussed. This review highlights the importance of microbiome in the development of MESs, effective operational factors for exo-electrogens activities as well their key challenges and future technological aspects are also briefly discussed.

An air exposed single-chamber microbial fuel cell (SCMFC) using microalgal biocathodes was designed. The reactors were tested for the simultaneous biodegradation of real dye textile wastewater (RTW) and the generation of bioelectricity. The results of digital image processing revealed a maximum coverage area on the biocathodes by microalgal cells of 42%. The atmospheric and diffused CO2 could enable good algal growth and its immobilized operation on the cathode electrode. The biocathode-SCMFCs outperformed an open circuit voltage (OCV), which was 18%–43% higher than the control. Furthermore, the maximum volumetric power density achieved was 123.2 ± 27.5 mW m−3. The system was suitable for the treatment of RTW and the removal/decrease of COD, colour and heavy metals. High removal efficiencies were observed in the SCMFCs for Zn (98%) and COD (92–98%), but the removal efficiencies were considerably lower for Cr (54–80%). We observed that this single chamber MFC simplifies a double chamber system. The bioelectrochemical performance was relatively low, but the treatment capacity of the system seems encouraging in contrast to previous studies. A proof-of-concept experiment demonstrated that the microalgal biocathode could operate in air exposed conditions, seems to be a promising alternative to a Pt cathode and is an efficient and cost-effective approach to improve the performance of single chamber MFCs.

Microbial fuel cells represent an innovative technology which allow simultaneous waste treatment, electricity production, and environmental monitoring. This study provides a preliminary investigation of the use of terrestrial Single chamber Microbial Fuel Cells (SMFCs) as biosensors. Three cells were created using Andean soil, each one for monitoring a BOD concentration of synthetic washed rice wastewater (SRWW) of 10, 100, and 200 mg/L for SMFC1, SMFC2 and SMFC3, respectively. The results showed transient, exponential, and steady stages in the SMFCs. The maximum open circuit voltage (OCV) peaks were reached during the elapsed time of the transient stages, according to the tested BOD concentrations. A good linearity between OCV and time was observed in the increasing stage. The average OCV in this stage increased independently of the tested concentrations. SMFC1 required less time than SMFC2 to reach the steady stage, suggesting the BOD concentration is an influencing factor in SMFCs, and SMFC3 did not reach it. The OCV ratios were between 40.6–58.8 mV and 18.2–32.9 mV for SMFC1 and SMFC2. The reproducibility of the SMFCs was observed in four and three cycles for SMFC1 and SMFC2, respectively. The presented SMFCs had a good response and reproducibility as biosensor devices, and could be an alternative for environmental monitoring.