Abstract This study developed a method for constructing hub-functional (HF) microbiomes based on an established polarity-reversal strategy and thermodynamic analysis, with nitrate as the cathodic electron acceptor. XDLVO theory analysis revealed that the slow startup of traditional biocathodes stemmed from strong Lewis acid−base repulsion, which could be greatly diminished by polarity reversal. For instance, at −0.5 V (vs Ag/AgCl; hereafter the same), the repulsion was reduced by 36610.39 KT, promoting microbial adhesion. Electrochemical, microbial, and physicochemical characterizations confirmed that the HF microbiomes established a synergistic metabolic interaction. Hub microorganisms acted as electron transfer bridges, while functional microorganisms realized efficient NO3−-N reduction. The optimal potential for directed formation of HF microbiomes was −0.5 V, achieving a NO3−-N removal efficiency of 91.1% and shortening the biocathode startup period compared to the nonpolarity reversal mode. Microbial community analysis showed that the HF microbiomes were dominated by electroactive hub genera (e.g., Rhodopseudomonas) and denitrifying functional genera (e.g., Paracoccus, norank_f_Chitinophagaceae), which synergistically enhanced electron transfer efficiency. This study provides a novel thermodynamic insight into directed microbiome regulation in BESs and solves the bottleneck of slow traditional biocathode formation, offering a promising approach for nitrate remediation.
Abstract Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants with potential ecological toxicity. Short-chain PFAS, such as perfluorobutanoic acid (PFBA), are often considered safer alternatives to long-chain compounds like perfluorooctanoic acid (PFOA), yet their effects on freshwater microorganisms remain poorly understood. This study systematically compared the toxic effects of PFBA and PFOA on Microcystis aeruginosa, integrating physiological assessments and untargeted metabolomics. At lower concentrations (0.01–1 mg/L), both PFAS had negligible effects, whereas higher concentrations (10–50 mg/L) significantly inhibited algal growth, reduced chlorophyll a and carotenoid contents, and induced oxidative stress. PFBA exhibited stronger acute toxicity, with a 72-h EC50 of 24.83 mg/L versus 43.55 mg/L for PFOA. Metabolomic profiling revealed that both PFAS disrupted key metabolic pathways, including energy production, carbohydrate metabolism, and nucleotide metabolism, impairing cellular homeostasis and physiological function. Notably, PFOA-exposed cells showed certain adaptive metabolic responses, such as upregulation of pyrimidine metabolism and glucuronidation-related detoxification pathways, whereas PFBA induced broader and more severe metabolic perturbations, including markers of lipid peroxidation. These findings provide new insights into the effects of PFBA and PFOA on algae and the environmental risk assessment of PFAS.
Abstract Large quantities of sludge are produced during municipal and industrial wastewater treatment. To achieve advanced treatment of sludge containing multiple hazardous substances, the dewatering stage is of paramount importance. This study developed a novel, low-temperature, thermally assisted (55 °C) peroxymonosulfate (PMS)–tannic acid (TA) sequential conditioning strategy to improve sludge dewaterability. The combined treatment significantly enhanced dewatering performance, reducing sludge cake water content from 88.81% to 74.60% and decreasing capillary suction time by 67.20%. Systematic investigations revealed that low-temperature, thermally assisted PMS oxidation effectively disrupted extracellular polymeric substances (EPS), while subsequent TA complexation optimized floc structure and improved hydrophobicity. The 55 °C operating temperature demonstrated superior efficiency compared to conventional high-temperature processes, providing an energy-saving alternative for sludge conditioning. Mechanistic studies through 3D-EEM and FT-IR analyses elucidated the critical role of protein/polysaccharide transformation in EPS during the conditioning process. This study presents a novel, energy-efficient pretreatment approach for advanced sludge treatment, offering significant implications for promoting sludge reduction and resource recovery.
Abstract Harmful algal blooms (HABs) pose a significant threat to aquatic ecosystems, public health, and economic activities worldwide. In this study, a highly efficient advanced oxidation process utilizing hydroxyl radicals (•OH) generated via strong ionization discharge at atmospheric pressure was applied to rapidly inactivate harmful algae collected during HABs in June 2022 in Pingtan coastal waters, which were dominated by the toxic species Karlodinium digitatum and Karenia papillonacea. Notably, the inactivation rates reached 98% ± 0.05% for a high algal density of 2500 cells/mL within an extremely short contact time of only 12 s, requiring low total reactive oxidant (TRO) concentrations of merely 0.5 to 1.0 mg/L. Meanwhile, •OH inactivated algal cells primarily while the cells remained morphologically intact, without visible lysis. This action mechanism effectively prevents the secondary release of intracellular organic matter and intracellular toxins, a common drawback of many physical and chemical treatments. Furthermore, the •OH treatment concurrently improved the overall water quality by significantly reducing total coliform counts. The technology demonstrated herein, characterized by its rapid response, high efficiency, minimal ecological impact, and dual function of algae inactivation and water purification, represents a highly promising and environmentally benign strategy for the emergency control and mitigation of HABs in water conservation projects.
