Reducing citrus effluent toxicity: Biological-electrochemical treatment with diamond anode.

One challenge of the citrus industry is the treatment and disposal of its effluents due to their high toxicity, substantial organic load, and consequent resistance to conventional biotechnological processes. This study introduces a novel approach, using electrochemical oxidation with a boron-doped diamond anode to efficiently remove organic compounds from biodegraded pulp wash (treated using the fungus Pleurotus sajor-caju.) The findings reveal that employing a current density of 20 mA cm-2 achieves notable results, including a 44.1% reduction in color, a 70.0% decrease in chemical oxygen demand, an 88.0% reduction in turbidity, and an impressive 99.7% removal of total organic carbon (TOC) after 6 h of electrolysis. The energy consumption was estimated at 2.93 kWh g-1 of removed TOC. This sequential biological-electrochemical procedure not only significantly reduced the mortality rate (85%) of Danio rerio embryos but also reduced the incidence of morphologically altered parameters. Regarding acute toxicity (LC50) of the residue, the process demonstrated a mortality reduction of 6.97% for D. rerio and a 40.88% lethality decrease for Lactuca sativa seeds. The substantial reduction in toxicity and organic load observed in this study highlights the potential applicability of combined biological and electrochemical treatments for real agroindustrial residues or their effluents.

Novel combination of iron-carbon composite and Fenton oxidation processes for high-concentration antibiotic wastewater treatment.

The research presented herein explores the development of a novel iron-carbon composite, designed specifically for the improved treatment of high-concentration antibiotic wastewater. Employing a nitrogen-shielded thermal calcination approach, the investigation utilizes a blend of reductive iron powder, activated carbon, bentonite, copper powder, manganese dioxide, and ferric oxide to formulate an efficient iron-carbon composite. The oxygen exclusion process in iron-carbon particles results in distinctive electrochemical cells formation, markedly enhancing wastewater degradation efficiency. Iron-carbon micro-electrolysis not only boosts the biochemical degradability of concentrated antibiotic wastewater but also mitigates acute biological toxicity. In response to the increased Fe2+ levels found in micro-electrolysis wastewater, this research incorporates Fenton oxidation for advanced treatment of the micro-electrolysis byproducts. Through the synergistic application of iron-carbon micro-electrolysis and Fenton oxidation, this research accomplishes a significant decrease in the initial COD levels of high-concentration antibiotic wastewater, reducing them from 90,000 mg/L to about 30,000 mg/L, thus achieving an impressive removal efficiency of 66.9%. This integrated methodology effectively reduces the pollutant load, and the recycling of Fe2+ in the Fenton process additionally contributes to the reduction in both the volume and cost associated with solid waste treatment. This research underscores the considerable potential of the iron-carbon composite material in efficiently managing high-concentration antibiotic wastewater, thereby making a notable contribution to the field of environmental science.

Effect and mechanism of iron-carbon micro-electrolysis pretreatment of organic peroxide production wastewater.

The wastewater from organic peroxide production has high chemical oxygen demand (COD) concentration and poor biodegradability, so it is necessary to find a cost-effective treatment method. The iron-carbon microelectrolysis (IC-ME) technology was used to pretreat the organic peroxide production wastewater, and the influence of reaction conditions on the removal effect of pollutants and the degradation mechanism were studied. The effects of initial pH, iron filings, iron-carbon ratio, and reaction time on the wastewater treatment were investigated by single-factor and response surface optimization experiments, and the degradation mechanism was analyzed by three-dimensional fluorescence spectroscopy, UV-Vis, and gas chromatography mass spectrometry (GC-MS). The experimental results showed that the COD removal efficiency was 35.67% and the biodegradability of wastewater was increased from 0.113 to 0.173 under the conditions of initial pH of 3.1, the dosage of iron filings of 30.5 g/L, the ratio of iron-carbon of 1.01, and the reaction time of 122.8 min, and the process of IC-ME for degrading COD of wastewater from the production of organic peroxide was consistent with the secondary reaction. The IC-ME process could decompose macromolecular organic compounds such as tyrosine proteins and aromatic proteins, and improve the biodegradability of wastewater. It provides a theoretical reference for the practical application of IC-ME to treat this type of wastewater.

Comparative study of exoelectrogenic utilization preferences and hydrogen conversion among major fermentation products in microbial electrolysis cells.

This study comparatively investigated the exoelectrogenic utilization and hydrogen conversion of major dark fermentation products (acetate, propionate, butyrate, lactate, and ethanol) from organic wastes in dual-chamber microbial electrolysis cells (MECs) alongside their mixture as a simulated dark fermentation effluent (DFE). Acetate-fed MECs showed the highest hydrogen yield (1,465 mL/g chemical oxygen demand), near the theoretical maximum yield, with the highest coulombic efficiency (105%) and maximum current density (7.9 A/m2), followed by lactate-fed, propionate-fed, butyrate-fed, mixture-fed, and ethanol-fed MECs. Meanwhile, the highest hydrogen production rate (514 mL/L anolyte∙d) was observed in ethanol-fed MECs despite their lower coulombic efficiency. Butyrate was the least favored substrate, followed by propionate, leading to significantly delayed startup and reaction. The active anodic microbial community structure varied considerably among the MECs utilizing different substrates, particularly between Geobacter and Acetobacterium dominance. The results highlight the substantial effect of the DFE composition on its utilization and current-producing bioanode development.

Overcoming hydrogen loss in single-chamber microbial electrolysis cells by urine amendment.

The effective hydrogen production in single-chamber microbial electrolysis cells (MECs) has been seriously challenged by various hydrogen consumers resulting in substantial hydrogen loss. In previous studies, the total ammonia nitrogen (TAN) has been used to inhibit certain hydrogen-consuming microorganisms to enhance hydrogen production in fermentation. In this study, we explored the feasibility of using source-separated urine to overcome hydrogen loss in the MEC, with the primary component responsible being TAN generated via urea hydrolysis. Experimental results revealed that the optimal TAN concentration ranged from 1.17 g N/L to 1.75 g N/L. Within this range, the hydrogen production rate substantially improved from less than 100 L/(m3·d) up to 520 L/(m3·d), and cathode recovery efficiency and energy recovery efficiency were greatly enhanced, with the hydrogen percentage achieved over 95 % of the total gas volume, while maintaining uninterrupted electroactivity in the anode. Compared to using chemically added TAN, using source separated urine as the source of ammonia also showed the effect of overcoming hydrogen loss but with lower Coulombic efficiency due to the complex organic components. Pre-adaptation of the reactor with urea enhanced hydrogen production by nearly 60 %. This study demonstrated the effectiveness of TAN and urine in suppressing hydrogen loss, and the results are highly relevant to MECs treating real wastewater with high TAN concentrations, particularly human fecal and urine wastewater.

New diamond coatings for a safer electrolytic disinfection.

In this work, a new coating of boron-doped diamond ultra-nanocrystalline (U-NBDD), tailored to prevent massive formation of perchlorates during disinfection, is evaluated as electrode for the reclaiming of treated secondary wastewater by the electrochemically assisted disinfection process. Results obtained are compared to those obtained by using a standard electrode (STD) that was evaluated as a standard in previous research showing outstanding performance for this application. First tests were carried out to evaluate the chlorine speciation obtained after the electrolysis of synthetic chloride solutions at two different ranges of current densities. Concentrations of hypochlorite obtained using the U-NBDD anode at 25 mA cm-2 were 1.5-fold higher, outperforming STD anode; however, at 300 mA cm-2, an overturn on the behavior of anodes occurs where the amount of hypochlorite produced on STD anode was 1.5-fold higher. Importantly, at low current density the formation of chlorates and perchlorates is null using U-NBDD. Then, the disinfection of the real effluent of the secondary clarifier of a municipal wastewater treatment facility is assessed, where inactivation of Escherichia coli is achieved at low charge applied per volume electrolyzed (0.08 A h L-1) at 25 mA cm-2 using the U-NBDD. These findings demonstrate the appropriateness of the strategy followed in this work to obtain safer electro-disinfection technologies for the reclaiming of treated wastewater.

Electrochemical degradation of ciprofloxacin through a DoE-driven optimization in a filter-press type reactor under batch recirculation mode.

In this work, the electrochemical degradation of ciprofloxacin (CIP) was studied in a filter-press-type reactor without division in a batch recirculation manner. For this purpose, two boron-doped diamond (BDD) electrodes (as cathode and anode) were employed. Also, the optimal operating conditions were found by response surface methodology (RSM) following a central composite face-centered design with three factors, namely current intensity (i), initial pH (pH0), and initial concentration ([C]0) with two responses, namely remotion efficiency (η) and operating cost. Optimal operating conditions were i = 3 A, pH0 = 8.49, and [C]0 = 33.26 mg L-1 within an electrolysis time of 5 h, leading to a maximum removal efficiency of 93.49% with a minimum operating cost of $0.013 USD L-1. Also, a TOC analysis shows an 80% of mineralization extent with an energy consumption of 5.11 kWh g-1 TOC. Furthermore, the CIP degradation progress was followed by mass spectrometry (LC/MS) and a degradation pathway is proposed.

Decentralized environmental applications of a smartphone-based method for chemical oxygen demand and color analysis.

This study is focused on a proposal of a smartphone imaging-based quantification for providing a simple and rapid method for the analysis of chemical oxygen demand (COD) and color throughout the use of the HSV and/or RGB model in digital devices. For COD, calibration curves were done based on the theoretical values of potassium biphthalate for a proper comparison between the spectrophotometer and the smartphone techniques. The smartphone camera and application attain an average accuracy higher than the analysis in the spectrophotometer (98.3 and 96.2%, respectively). In the color analysis, it was demonstrated that only the UV-vis bands measurement is not feasible to perform the real abatement of the dye in the water because the limiting concentration that allows obtaining a linear relationship in this equipment related to the dye concentration is about 10 mg L-1. Above this value, the spectrophotometer can not reach the real difference of color in the solution. Meanwhile, the smartphone method by using the camera reaches linearity until 50 mg L-1. From an environmental point of view, smartphones have been used for monitoring several organic and inorganic pollutants, however, no attempts have been published related to their use to evaluate the color and COD during wastewater treatment. Therefore, this investigation also aims to assess the utilization of these methods, for the first time, when high-colored water polluted by methylene blue (MB) was electrochemically treated by using a boron-dopped diamond (BDD) as the anode, with different current densities (j = 30, 45, 60, and 90 mA cm-2). COD and color abatement results clearly showed that different organic matter/color removal efficiencies were achieved, depending on the j used. All the results are aligned with the studies already available in the literature, with the total removal of color in 120 min of electrolysis with 60 and 90 mA cm-2, and almost 80% of COD abatement with the higher j. Moreover, samples of real effluent from beauty salons were compared, with standard deviation varying from only 3 to 40 mg O2 L-1, which is acceptable for COD values close to 2000. Finally, the methods here presented can be a great benefit for public water monitoring policies, since it is cheap and has a decentralized characteristic, given that smartphones are very common and portable devices.

Development of a new photoelectrochemical system for clean hydrogen production and a comparative environmental impact assessment with other production methods.

Hydrogen is recognized as a critical substance for diversifying the global energy supply, providing new economic opportunities and realizing a carbon-free energy sector. In the current study, a life cycle assessment is conducted on a photoelectrochemical hydrogen production process of a newly developed photoelectrochemical reactor. With a photoactive electrode area of 870 cm2, the hydrogen production rate of the reactor is 47.1 µg/s while operating with the energy and exergy efficiencies of 6.3% and 6.31%, respectively. For a Faradaic efficiency of 96%, the produced current density is evaluated as 3.15 mA/cm2. A comprehensive study is conducted for a cradle-to-gate life cycle assessment of the proposed hydrogen photoelectrochemical production system. The life cycle assessment results of the proposed photoelectrochemical system are further evaluated within a comparative analysis by considering a total of four key hydrogen generation processes, namely steam-methane reforming, photovoltaics-based and wind electricity-driven proton exchange membrane water electrolysis and the current photoelectrochemical system and studying five environmental impact categories. The global warming potential of hydrogen production via the proposed photoelectrochemical cell is evaluated as 1.052 kg CO2 equivalent per kg of produced hydrogen. In the normalized comparative life cycle assessment results, the PEC-based hydrogen production is found to be the most nature-friendly option among the considered pathways.

Bioaugmentation of microbial electrolysis cells with Geobacter sulfurreducens YM18 for enhanced hydrogen production from starch.

Double-chamber microbial electrolysis cells (MECs) were operated using starch-based medium as the anolyte and rice paddy-field soil as the anode inoculum, and hydrogen production from the cathode chamber was examined. In order to enhance current generation and hydrogen production, the anode chamber was bioaugmented with Geobacter sulfurreducens strain YM18, and its effects were evaluated based on the performances of non-bioaugmented controls. Results show that the bioaugmented MEC generated threefold greater current during one-month operation and produced sixfold greater amounts of hydrogen than those of the non-bioaugmented control. Quantitative PCR and metabarcoding analyses confirmed successful colonization of anode surfaces with YM18, suggesting the utility of bioaugmentation with YM18 for enhancing the performance of bioelectrochemical systems, including MECs treating biomass wastes.

Novel ternary Cu0-coupled core-shell Fe0/C nanoparticles micro-electrolysis system toward degradation of organic pollutants: Synergistic effects and removal mechanism.

A ternary micro-electrolysis system consisting of carbon-coated metallic iron with Cu nanoparticles (Fe0/C@Cu0) was synthesized for the degradation of sulfathiazole (STZ). Fe0/C@Cu0 catalysts exhibited excellent reusability and stability owing to the inner tailored Fe0 with persistent activity. The connection between Fe and Cu elements in the Fe0/C-3@Cu0 catalyst prepared with iron citrate as iron source exhibited a tighter contact than the catalysts prepared with FeSO4·7H2O and iron(II) oxalate as iron sources. Especially, unique core-shell structure of Fe0/C-3@Cu0 catalyst is more conducive to promoting the degradation of STZ. A two-stage reaction with rapidly degradation followed by gradual degradation was revealed. The mechanism of STZ degradation could be explained by the synergistic effects of Fe0/C@Cu0. Carbon layer with remarkable conductivity allowed electrons from Fe0 transferred freely to the Cu0. The electron-rich Cu0 releases electrons, facilitating the degradation of STZ. Furthermore, the high potential difference between cathode (C and Cu0) and anode (Fe0) accelerate the corrosion of Fe0. Importantly, Fe0/C@Cu0 catalysts exhibited excellent catalytic performance for sulfathiazole degradation in landfill leachate effluent. Results presented provide a new strategy for treatment of chemical wastes.

Exploratory study on tissue ablation with cryoelectrolysis.

This is an exploratory study on the effect of electrolysis, delivered during the thawing stage of a cryoablation protocol, on tissue ablation. This treatment protocol, that combines freezing and electrolysis, is named "cryoelectrolysis". In cryoelectrolysis the cryoablation probe is also used as the electrolysis delivering electrode. The study was performed on the liver of Landrace pigs and the tissues were examined 24 hours after treatment (two pigs) and 48 hours after treatment (one pig). The cryoelectrolysis device and different cryoelectrolysis ablation configurations tested are described. This exploratory, non-statistical study shows that the addition of electrolysis expands the ablated area in comparison to cryoablation alone and that there is a substantial difference between the histological appearance of tissue treated by cryoablation alone, tissue treated by cryoablation and electrolysis at the anode and tissue treated by cryoablation and electrolysis at the cathode.

Pulsed Electrolysis of Boron-Doped Carbon Dramatically Improves Impurity Tolerance and Longevity of H2O2 Production.

Electrocatalytic water treatment has emerged in the limelight of scientific interest, yet its long-term viability remains largely in the dark. Herein, we present for the first time a comprehensive framework on how to optimize pulsed electrolysis to bolster catalyst impurity tolerance and overall longevity. By examining real wastewater constituents and assessing different catalyst designs, we deconvolute the complexities associated with key pulsing parameters to formulate optimal sequences that maximize operational lifetime. We showcase our approach for cathodic H2O2 electrosynthesis, selected for its widespread importance to wastewater treatment. Our results unveil superior performance for a boron-doped carbon catalyst over state-of-the-art oxidized carbon, with high selectivity (>75%) and near complete recoveries in overpotentials even in the presence of highly detrimental Ni2+ and Zn2+ impurities. We then adapt these fine-tuned settings, obtained under a three-electrode arrangement, for practical two-electrode operation using a novel strategy that conserves the desired electrochemical potentials at the catalytic interface. Even under various impurity concentrations, our pulses substantially improve long-term H2O2 production to 287 h and 35 times that attainable via conventional electrolysis. Our findings underscore the versatility of pulsed electrolysis necessary for developing more practical water treatment technologies.

Sequential dark fermentation and microbial electrolysis cells for hydrogen production: Volatile fatty acids influence and energy considerations.

Hydrogen production from food waste by coupling dark fermentation (DF) and microbial electrolysis cells (MEC) was studied. Metabolic patterns in DF, their effects on MECs efficiency, and the energy output of the coupling were investigated. Mesophilic temperature and acidic pH 5.5 resulted in 72 ± 20 mL H2/g CODin and a butyrate-enriched profile (C2/C4, 0.5-0.6) contrasting with an acetate-enriched profile (C2/C4, 1.8-1.9) and 36 ± 10 mL H2/g CODin at pH 7. Assessment in series of the DF effluents in MECs resulted in a higher hydrogen yield (566-733 mL H2/g CODin) and volatile fatty acids (VFAs) removal (84-95%) obtained from pH 7 effluents compared to pH 5.5 effluents (173-186 mL H2/g CODin and 29-59%). Finally, the output energy was lower in DF at pH 7, however, these effluents retrieved the highest energy in the MEC, showing the importance of process pH and VFAs profile to balance the coupling.

Inactivation of Microcystis aeruginosa by H2O2 generated from a carbon black polytetrafluoroethylene gas diffusion electrode in electrolysis by low-amperage electric current.

Frequent outbreaks of cyanobacterial blooms have seriously threatened aquatic ecological environments and human health. Electrolysis by low-amperage electric current is effective for algae inactivation; however, it has no selectivity. Hydrogen peroxide (H2O2) is considered to be an efficient and selective suppressor of algae. Therefore, it is necessary to develop an electrode that can generate H2O2 to improve electrolysis technology. In this study, a carbon black polytetrafluoroethylene gas diffusion electrode (C-PTFE GDE) with good stability was prepared by a simple adhesive coating method. Then, the inactivation of Microcystis aeruginosa was conducted with electrolysis by low-amperage electric current using Ti/RuO2 as the anode and C-PTFE GDE as the cathode. When the electrode spacing was 4 cm, the current density was 20 mA cm-2, and the gas flow was 0.4 L min-1, 85% of the algae could be inactivated in 20 min. Comparing the inactivation effect of the electric field and electrogenerated oxidants, it was found that electrolysis more rapidly and strongly inactivated algae when an electric field existed. However, electrogenerated oxidants dominated algae inactivation. The concentration of H2O2 was as high as 58 mg L-1, while the concentration of chlorines was only 0.57 mg L-1, and the generation rate of H2O2 was 65 times that of chlorines. Consequently, electrogenerated oxidants dominated by H2O2 attacked photosystem II of the algae and caused oxidative damage to membrane lipids, affecting the photosynthetic capacity. Eventually, most of the algae were inactivated. The study suggested that C-PTFE GDE was promising for the inactivation of Microcystis aeruginosa in this electrochemical system.

Characteristic analysis of s-Fe/Cu two-component micro-electrolysis materials and degradation of dye wastewater.

Micro-electrolysis is a pretreatment technology for difficult-to-biodegrade wastewater. In this study, a chemical displacement method was used to load copper on the surface of sponge iron (s-Fe), and then it was mixed with activated carbon and other components to obtain a multi-element micro-electrolytic filler (OMEF). Through BET, SEM, XRD, XPS, and FT-IR characterization and analysis, OMEF was proved to have a specific surface area of 88.374 m2/g, C-C, C-O, C = O, O-C = O, and other functional groups and Fe3C, MnO2 and other active materials. The removal mechanism of organic pollutants in wastewater by OMEF could be due to the galvanic reaction, direct reduction of Fe, oxidation of Fe, catalytic oxidation of Cu and Mn, and co-precipitation of adsorption. The coupling of the micro-electrolysis and biological methods proved that OMEF had excellent application efficiency. The results indicated that the COD removal rates of OMEF and commercial fillers reached 88.39% and 48.02%, respectively, and the B/C reached 0.74 and 0.3. OMEF showed a better performance. The reusability of the OMEF filler was measured to ensure that the B/C was maintained at around 0.5 during 5 cycles. Kinetic analysis showed that the degradation data of methyl orange (MO) and the removal data of COD obeyed pseudo-second-order kinetics. Moreover, it can further broaden the pH range of treated wastewater and increase the oxidation rate. This new strategy has brought potential enlightenment for the development of high-efficiency wastewater pretreatment using new micro-electrolysis materials. The excellent performance of OMEF micro-electrolytic filler in pretreatment indicated its potential for industrial application.

Micro-electrolysis based nitrate reduction from aqueous solution by CNTs-Al-Cu composite under alkaline environment.

CNTs-Al was prepared by ball milling combined with sintering process and then used for CNTs-Al-Cu synthesis with chemical deposition method. The obtained CNTs-Al-Cu composite was systematically characterized and its NO3--N reduction performance under alkaline condition was also evaluated. As indicated by the reduction batch experiment, 80.2% of NO3--N removal efficiency was obtained in 90 min at pH of 9. The product of the reduction process was dominated by NO2--N, which was further reduced to harmless N2. The reusability of CNTs-Al-Cu composite was evaluated, and the experiment results showed that 68.1% of NO3--N removal efficiency was maintained after 3 cycles of regeneration. Finally, based on the characterization results and kinetic analysis, it was concluded that micro-electrolysis was mainly responsible for the removal of NO3--N by CNTs-Al-Cu.

Efficacy of percutaneous electrolysis for the treatment of tendinopathies: A systematic review and meta-analysis.

OBJECTIVE: To evaluate the efficacy of percutaneous electrolysis for the treatment of patients with tendinopathies. DATA SOURCES: A systematic search of publications was conducted in Pubmed, Cinahl, Medline, Scopus and Web of Science. METHODS: The Oxford 2011 Levels of Evidence and the Jadad scale were used to assess the quality of studies. The mean and standard deviation were obtained for each study group and used to calculate the effect size. The DerSimonian and Laird method was used to develop a random-effects model. RESULTS: Of the 14 articles, four applied percutaneous electrolysis to the knee, three to the shoulder, three to the elbow, two to the hip and two to the ankle and foot. A meta-analysis on intensity of pain (evaluated with algometer and the Visual Analogue Scale) was performed on studies comparing percutaneous electrolysis with a control group, indicating that the groups treated with percutaneous electrolysis had better results (p = 0.01). Although percutaneous electrolysis did not overcome the analgesic effect achieved by corticosteroid injections. CONCLUSIONS: The percutaneous electrolysis is effective for the treatment of tendinopathies. The combination of this technique with eccentric training has proven to be one of the most effective treatments to date for improving pain. PROSPERO Registration: CRD42021230005.

Ultrasound-Guided Percutaneous Needle Electrolysis Combined With Therapeutic Exercise May Add Benefit in the Management of Soleus Injury in Female Soccer Players: A Pilot Study.

CONTEXT: The performance of sprints during male soccer matches usually is slow medium paced, where the soleus and gastrocnemius (ankle plantar flexors) play a very important role. As in male soccer, soleus injuries should be considered in female soccer; but the scientific evidence is very limited in this case. DESIGN: Pilot clinical trial study. OBJECTIVE: To determine whether adding an ultrasound-guided percutaneous needle electrolysis (US-guided PNE) technique to a specific exercise program improved perceived pain at stretching and at palpation, ankle dorsiflexion range of motion, muscle fatigue, and sport performance in women soccer players with soleus injury. METHODS: This pilot study recruited 20 female players with chronic soleus injury (type 1, characterized by hypoechoic image) who were assigned to one of 2 groups: an experimental group (exercise program + US-guided PNE; n = 10) or a control group (exercise program + sham stimulation; n = 10). Pain intensity, dorsiflexion range of motion, knee-flexion heel raise test, curve sprint test, and the global rating of change scale were analyzed at baseline and after treatment (4 wk) and there was no further follow-up. RESULTS: Pain intensity at palpation and at stretching, dorsiflexion range of motion, and heel raise test values showed significant improvements (P < .05) between pretreatment and posttreatment for both groups, however, no significant differences were observed between groups. Curve sprint tests did not show significant differences between pretreatment and posttreatment for either group or between groups. However, the percentage of changes always revealed better values in favor of the PNE group. Both groups showed good player satisfaction with the therapies. CONCLUSION: The application of the US-guided PNE combined with a specific exercise program may cause clinical benefits in the treatment of female soccer players with soleus injury.

Promoted Sb removal with hydrogen production in microbial electrolysis cell by ZIF-67-derived modified sulfate-reducing bacteria bio-cathode.

Bio-cathode Microbial electrolysis cell (MEC) has been widely discovered for heavy metals removal and hydrogen production. However, low electron transfer efficiency and heavy metal toxicity limit MEC treatment efficiency. In this study, ZIF-67 was introduced to modify Sulfate-reducing bacteria (SRB) bio-cathode to enhance the bioreduction of sulfate and Antimony (Sb) with hydrogen production in the MEC. ZIF-67 modified bio-cathode was developed from a bio-anode microbial fuel cell (MFC) by operating with an applied voltage of 0.8 V to reverse the polarity. Cyclic voltammetry, linear sweep voltammetry and electrochemical impedance were done to confirm the performance of the ZIF-67 modified SRB bio-cathode. The synergy reduction of sulfate and Sb was accomplished by sulfide metal precipitation reaction from SRB itself. Maximum sulfate reduction rate approached 93.37 % and Sb removal efficiency could reach 92 %, which relies on the amount of sulfide concentration generated by sulfate reduction reaction, with 0.923 ± 0.04 m3 H2/m3 of hydrogen before adding Sb and 0.857 m3 H2/m3 of hydrogen after adding Sb. The hydrogen was mainly produced in this system and the result of gas chromatography (GC) indicated that 73.27 % of hydrogen was produced. Meanwhile the precipitates were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy to confirm Sb2S3 was generated from Sb (V).