Microbial electrosynthesis (MES) offers a promising carbon sequestration strategy for climate change mitigation, which also provides a sustainable pathway for biomass accumulation and bioenergy resource recovery. However, one key factor that governs electrosynthesis efficiency is electrode material. In this work, four electrodes including graphene electrodes (Gr), high-temperature calcined graphene electrodes (HG), graphene composite nanometal oxide with Fe2O3 (HFG) and TiO2 (HTG) were prepared to investigate the electroreduction effect on CO2 reduction activity, aiming to optimize the conversion of carbon resources into high-value biomass and renewable bioenergy products. The cathodic surface properties affect biofilm biomass and carbon-fixing bacteria abundance obviously. The biomass and electron transfer system activity (ETSA) were negatively correlated with charge transfer resistance. In comparison with the unmodified carbon felt as the cathode in the MES reactor, the acetic acid production in the subsequent four groups (388.62, 402.23, 441.77, and 489.81 mg/L) was significantly higher than that in the CF group (330.19 mg/L). As a typical bioenergy intermediate product, acetic acid is closely related to microbial biomass metabolism. Total carbon-fixing bacteria abundance was strongly positively correlated with acetic acid production (r = 0.914, p < 0.01). The Fe2O3 and TiO2 modified graphene cathodes enhanced both biofilm growth and carbon sequestration bacterial abundance respectively, optimized hydrogen evolution reaction kinetics and promoted the acetic acid production significantly.
Perfluoroalkyl acids (PFAAs) are ubiquitous contaminants in freshwater ecosystems, yet assessing their ecological risks remains challenging due to the selection of baseline organism and accurate trophic-level (TL) estimation. Here, we investigated the occurrence and trophic transfer of PFAAs in Chaohu Lake, China, by reconstructing the aquatic food web using stable isotope analysis. Submerged macrophytes were selected as the trophic baseline organism (TL = 1.0) and compared with the results of zooplankton. Two novel indicators, Risk-TMF (RTMF) and Risk-BMF (RBMF), were proposed to assess compound-specific risks by incorporating trophic magnification and biomagnification processes. Our results showed that perfluorooctanesulfonic acid (PFOS) and perfluorobutanesulfonic acid (PFBS) exhibited the highest bioaccumulation potential, while perfluorobutanoic acid (PFBA) and perfluorohexanoic acid (PFHxA) posed considerable ecological risks mainly due to their high environmental concentrations. Notably, no significant correlation was observed between PFAA concentrations and bioaccumulation factors in aquatic organisms (p > 0.05), highlighting the need for integrated bioaccumulation factors when evaluating their risks. PFBS, although often considered as a safer alternative to PFOS, displayed comparable or higher risk when bioaccumulation was taken into account. Overall, this study provides a refined and cost-effective approach for assessing the ecological risks of PFAAs in freshwater ecosystems.
This study investigated the co-pyrolysis char of oily sludge and sawdust, without chemical activation, as an efficient adsorbent for treating emulsified oily wastewater, a challenging industrial problem. Pyrolysis was conducted at temperatures of 400–700 °C and feedstock mixing ratios (sawdust-to-sludge, 1:1–4:1), with the char obtained under optimal conditions (600 °C, 4:1) without chemical activation, yielding an adsorption capacity of 413.32 mg/g. The co-pyrolysis char showed substantially higher adsorption performance than oily sludge-derived char (86.91 mg/g), while exhibiting relatively better performance than sawdust biochar (388.52 mg/g). The char was subsequently modified via ball milling to enhance its adsorption properties, and its adsorption capacity increased to 538.36 mg/g due to increased surface area, pore volume, and functional groups, despite a reduction in hydrophobicity. Characterization revealed that a higher sawdust ratio in co-pyrolysis feedstock significantly enhanced the char’s porosity and surface area, while the adsorption behavior was mainly associated with pore filling, hydrophobic interactions, π-π stacking, and hydrogen bonding. The adsorption process was best described by the pseudo-second-order kinetic model and the Langmuir isotherm. This study addressed the dual challenges of waste valorization and emulsified oily wastewater treatment by developing a cost-effective solution that offers practical implications for industrial-scale applications.
Wastewater treatment plants represent an invaluable reservoir of microbial resources yet remain largely unexplored. By selective sampling and integrative analysis of 828 metagenomic data from wastewater treatment plants spanning six continents, we established a global-scale metagenomic catalogue for activated sludge, including 24,536 metagenome-assembled genomes (MAGs) and over 24 million non-redundant genes, uncovering 12,563 MAGs without species-level definition and generating a high‑resolution, MAG‑level relative abundance and distribution map capturing their global distribution. This global-scale collection of MAGs enhances existing knowledge about functional microorganisms, including polyphosphate-accumulating organisms, nitrifiers, denitrifiers, refining the understanding of nutrient removal in wastewater treatment. By systematically annotating genes involved in nutrient removal, virulence factors, plastic degradation and biosynthesis, we integrated phylogenetics with metabolic potential, revealing previously under-characterized microbes and their diversity. Tthis study provides a comprehensive, genome-resolved framework and essential resources for targeted genome-centric research, guiding directed wastewater treatment engineering and the development of innovative treatment processes. Wastewater treatment plants harbour extensive but poorly characterized microbial genetic diversity. Using 828 metagenomes from wastewater treatement plants globally, this study reconstructs >24,000 metagenome-assembled genomes, including >12,000 new species, providing a genome-resolved framework for understanding and engineering activated sludge functions.
In this study, a Cu/Fe-dual single-atom catalyst (Cu/Fe-N-C) was prepared in combination with carbon nitride (gC(3)N(4) ) and subjected to phosphating treatment. The resulting Cu/Fe-N-C-P/g-C3N4 composite electrode was used for efficient separation of uranium from aqueous solutions. Under identical conditions (pH 6, initial U concentration: 10 mg/L), the Cu/Fe-N-C-P/g-C3N4 composite electrode achieved a uranium removal rate of 99% within just 20 min, significantly outperforming the individual electrochemical treatment by Cu/Fe-N-C-P 75% in 20 min) and the individual photocatalytic treatment by g-C3N4 (38.6% in 20 min). Mechanism analysis indicates that under PEC conditions, the migration of UO22+ toward the Fe/Cu-Nx sites on the electrode was enhanced. Uranyl ions reaching the surface were primarily reduced to U(V) by the copper-iron bimetallic single-atom catalyst and subsequently underwent oxidized to form Na2O(UO3 & sdot;H2O)x precipitate. Meanwhile, some uranium ions were directly reduced by photogenerated electrons to U(IV), which together with the above precipitate were deposited at the bottom of the reactor, achieving efficient separation and solidification of uranium from the aqueous phase. When treating actual uranium-containing wastewater, after 12 h of microalgae biological adsorption pretreatment, followed by photoelectric treatment, the uranium removal rate within 5 min could reach almost complete removal (>99.9%), which was much higher than the direct photoelectric treatment removal effect of 56.6%. This integrated process of photoelectrocatalytic and biological pre-treatment significantly enhanced the efficiency of selective separation of uranium from complex aqueous systems by strengthening the migration, enrichment, and phase separation processes of the target substance.
