The anode is more beneficial to the advanced treatment of wastewater containing antibiotics by three-dimensional electro-biofilm reactor: Degradation, mechanism and optimization

Doxycycline degradation by Enterobacter cloacae HS-08: A comparative analysis of biodegradation and bio-electrodegradation approaches with toxicity implications

Doxycycline (DOX), a commonly prescribed antibiotic, poses a growing environmental concern due to its recalcitrant nature, insufficient removal by conventional treatment methods, and detrimental effects on ecosystems and living organisms. This study evaluates the comparative efficacy of biodegradation and bio-electrodegradation approaches for DOX removal using Enterobacter cloacae HS-08, focusing on degradation efficiency, intermediate toxicity, systemic impacts, and gut microbiome alterations. The results showed that biodegradation achieved 61% DOX removal (75 mg/L) within 8 days; however, HPLC-MS/MS analysis revealed the formation of toxic intermediates, resulting in residual toxicity. Interestingly, bio-electrodegradation demonstrated superior performance, achieving 99.19% degradation under optimized conditions with minimal toxic intermediates. In-vivo toxicity studies using mice revealed that untreated DOX effluent significantly reduced body weight, food intake, and organ health while disrupting gut microbiome composition, marked by reduced diversity and dysbiosis. Biodegradation effluent exhibited moderate toxicity, reflecting the lingering effects of intermediate by-products. Conversely, bio-electrodegradation effluent mitigated toxicity, preserved gut microbiome structure and diversity, and supported normal physiological function, with growth, appetite, and organ health comparable to the control group. These findings highlight the critical need to address doxycycline contamination and emphasize the superior efficacy of bio-electrodegradation as a sustainable solution for mitigating pharmaceutical pollutants and restoring ecological balance.

The corrosion mechanism of Q355 steel electrically connected to the Al-Zn-In-Cd sacrificial anode: From microbial community to corrosion behavior analysis

Microbially induced corrosion caused by sulfate-reducing bacteria (SRB) poses a significant threat to marine engineering facilities. Cathodic protection technology is a widely used method to prevent the corrosion of buried pipelines. The applied cathodic potential not only induce corrosion behavior change of steel but also triggers changes in the dominant microorganisms. In this study the corrosion behavior and microbial community characteristics of Q355 steel electrically connected to the Al-Zn-In-Cd sacrificial anode were studied. It was found that cathodic protection efficiency of Al-Zn-In-Cd alloy coupons with respect to Q355 steel in SRB media reached 40.17 %, while in natural seawater, the cathodic protection efficiency achieving a remarkable CP efficiency of 99.21 %. Besides of lepidocrocite (γ-FeOOH), halite, magnetite and Fe1-xS, more quartz was formed on cathodic protection protected steel surfaces compared with that without protection. Besides, more electroactive bacteria like Exiguobacterium, were found on the cathodic protection protected steel surfaces, which is related to the higher electron density and a polarized electric field.

Electrocatalytic coupled biofilter for treating cyclohexanone-containing wastewater: Degradation, mechanism and optimization

Electrocatalytic coupled biofilter (EBF) technology organically integrates the characteristics of electrochemistry and microbial redox, providing ideas for effectively improving biological treatment performance. In this study, an EBF system was developed for enhanced degradation of cyclohexanone in contaminated water. Experimental results show that the system can effectively remove cyclohexanone in contaminated water. Under the optimal parameters, the removal rates of cyclohexanone, TP, NH4+-N and TN were 97.61 ± 1.31%, 76.31 ± 1.67%, 94.14 ± 2.13% and 95.87 ± 1.01% respectively. Degradation kinetics studies found that electrolysis, adsorption, and biodegradation pathways play a major role in the degradation of cyclohexanone. Microbial community analysis indicates that voltage can affect the structure of the microbial community, with the dominant genera shifting from Acidovorax (0 V) to Brevundimonas (0.7 V). Additionally, Acidovorax, Cupriavidus, Ralstonia, and Hydrogenophaga have high abundance in the biofilm and can effectively metabolize cyclohexanone and its intermediates, facilitating the removal of cyclohexanone. In summary, this research can guide the development and construction of highly stable EBF systems and is expected to be used for advanced treatment of industrial wastewater containing cyclohexanone.

Advances and solutions in biological treatment for antibiotic wastewater with resistance genes: A review

Biological treatment represents a fundamental component of wastewater treatment plants (WWTPs). The transmission of antibiotic resistance bacteria (ARB) and resistance genes (ARGs) occurred through the continuous migration and transformation, attributed to the residual presence of antibiotics in WWTPs effluent, posing a significant threat to the entire ecosystem. It is necessary to propose novel biological strategies to address the challenge of refractory contaminants, such as antibiotics, ARGs and ARB. This review summarizes the occurrence of antibiotics in wastewater, categorized by high and low concentrations. Additionally, current biological treatments used in WWTPs, such as aerobic activated sludge, anaerobic digestion, sequencing batch reactor (SBR), constructed wetland, membrane-related bioreactors and biological aerated filter (BAF) are introduced. In particular, because microorganisms are the key to those biological treatments, the effect of high and low concentration of antibiotics on microorganisms are thoroughly discussed. Finally, solutions involving functional bacteria, partial nitrification (PN)-Anammox and lysozyme embedding are suggested from the perspective of the entire biological treatment process. Overall, this review provides valuable insights for the simultaneous removal of antibiotics and ARGs in antibiotics wastewater.

A review on three-dimensional electrochemical technology for the antibiotic wastewater treatment

The potential genotoxicity and non-biodegradability of antibiotics in the natural water bodies threaten the survival of various living things and cause serious environmental pollution and destruction. Three-dimensional (3D) electrochemical technology is considered a powerful means for antibiotic wastewater treatment as it can degrade non-biodegradable organic substances into non-toxic or harmless substances and even completely mineralize them under the action of electric current. Therefore, antibiotic wastewater treatment using 3D electrochemical technology has now become a hot research topic. Thus, in this review, a detailed and comprehensive investigation was conducted on the antibiotic wastewater treatment using 3D electrochemical technology, including the structure of the reactor, electrode materials, the influence of operating parameters, reaction mechanism, and combination with other technologies. Many studies have shown that the materials of electrode, especially particle electrode, have a great effect on the antibiotic wastewater treatment efficiency. The influence of operating parameters such as cell voltage, solution pH, and electrolyte concentration was very significant. Combination with other technologies such as membrane and biological technologies has effectively increased antibiotic removal and mineralization efficiency. In conclusion, the 3D electrochemical technology is considered as a promising technology for the antibiotic wastewater treatment. Finally, the possible research directions of the 3D electrochemical technology for antibiotic wastewater treatment were proposed.

Mechanism on the microbial salt tolerance enhancement by electrical stimulation

The application of biological methods in industrial saline wastewater treatment is limited, since the activities of microorganisms are strongly inhibited by the highly concentrated salts. Acclimatized halotolerant and halophilic microorganisms are of high importance since they can resist the environmental stresses of high salinity. The acclimation to salinity can be passive or active based on whether external simulation is used. However, there is a need for development of economic, efficient and reliable active biological stimulation technologies to accelerate salinity acclimation. Recent studies have shown that electrical stimulation can effectively enhance microbial salt tolerance and pollutant removal ability. However, there have been no comprehensive reviews of the mechanisms involved. Therefore, this mini-review described the mechanisms of electrical stimulation that can significantly improve microbial bioactivity and biodiversity. These mechanisms include regulation of Na⁺ and K⁺ transporters by changing membranepotential and promoting ATP production, as well as regulation of extracellular polymer substances through enhanced release of low molecular weight EPS and quorum sensing molecules. The information provided herein will facilitate the application of biological high-salinity wastewater treatment.