Anaerobic digestion provides an essential pathway for reducing organic waste while simultaneously recovering bioenergy. To enhance this process, magnetic biochars are frequently employed as conductive additives to promote direct interspecies electron transfer (DIET) among syntrophic microorganisms. However, the fundamental mechanisms regarding how iron species leached from these materials influence iron transformation and electron flux remain poorly understood. Here we show that the leaching of iron species from magnetic biochar establishes a stable Fe(Ⅲ)/Fe(Ⅱ) redox cycle that accelerates the hydrolysis, acidogenesis, and methanogenesis of waste-activated sludge. We find that cumulative methane production increases by 17% as leached Fe(Ⅲ) facilitates dissimilatory iron reduction, followed by secondary mineralization into high-crystalline iron species. This process selectively enriches electroactive taxa, including Geobacter and Methanothrix, and transitioned the dominant electron transfer mechanism from cytochrome c-dependent pathways to a Fe(Ⅲ)/Fe(Ⅱ) redox-driven DIET. These mechanisms advance our understanding of conductive material-mediated AD, offering strategies to optimize energy recovery from waste-activated sludge and support sustainable sludge management in wastewater treatment.

The global intensification of harmful algal blooms severely compromises freshwater ecosystems, threatening biodiversity and critical ecosystem services through toxin exposure, hypoxia, and water quality degradation. Bloom formation involves a complex interplay of nutrient dynamics, hydrology, and microbial activity. Although subsurface processes—such as the release of sediment-bound nutrients and the germination of dormant cyanobacteria—are thought crucial to bloom initiation, these phenomena occur at fine spatiotemporal scales beyond the reach of conventional monitoring. As a result, the exact, rapidly evolving triggers of bloom emergence remain mostly unknown. Here we show meter-scale chlorophyll a (Chl-a) plumes rising from the sediment–water interface, triggered by heavy rainfall and directly seeding surface blooms. We captured these dynamics using a custom underwater drone that collected over 2.8 million data points at 5-m horizontal and 1-m vertical resolution. Algal blooms exhibit a clear vertical sequence: anomalous Chl-a levels first appear in deep benthic layers after rainfall-driven resuspension, then intensify simultaneously across near-bed depths, and finally reach the surface after a median lag of 0.8–1.5 days. These observations provide in situ evidence associating benthic algal seed stocks with surface bloom initiation, revealing that the origin and spatial heterogeneity of such events arise from rainfall-driven disturbances at the sediment–water interface. This robotic approach not only deciphers the subsurface origins of algal blooms but also empowers predictive modeling and adaptive management strategies, advancing global efforts to combat eutrophication amid escalating climate pressures and safeguard vital water resources.

Microbial electrorespiration harnesses bacteria to drive reductive dechlorination, offering a sustainable method to remediate environments contaminated with persistent chlorinated organic pollutants (COPs). However, aquifers' complex hydrogeological and hydrochemical conditions, combined with uneven COP distribution, create substantial spatial and temporal variability in biochemical reactions, environmental factors, and microbial communities. Traditional trial-and-error experiments are labor-intensive and slow, impeding the quick identification of conditions that accelerate dechlorination rates. Here we show that a machine learning framework, integrating experimental design with cathodic biofilm data, uncovers key interrelationships among environmental variables, dechlorination kinetics, electrochemical properties, and functional microbes, enabling rapid optimization of bioelectrodechlorination. Trained on literature-derived datasets using models such as extreme gradient boosting, random forest, and multilayer perceptron, this framework identifies temperature and cathode potential as primary drivers in experimental design while highlighting key biofilm genera, including Clostridium, Desulfovibrio, Dehalococcoides, Pseudomonas, Dehalobacter, Arcobacter, Lactococcus, and Geobacter. It supports inverse design to determine optimal parameters—such as cathode potential, temperature, and additives—for dechlorinating representative COPs, including tetrachloroethene, trichloroethene, and 1,2-dichloroethane, achieving reaction rate predictions with errors below 6%. This approach surpasses conventional methods by increasing efficiency, cutting costs, and accelerating bioremediation without extensive laboratory testing. By incorporating microbial community insights into predictive models, our data-driven strategy advances the scalable application of microbial electrorespiration for COP-contaminated water remediation and paves the way for broader bioelectrochemical uses in environmental engineering.

Sustainable detoxification and advanced treatment of toxic organic pollutants (TOPs) in wastewater are essential for water reclamation and ecosystem security. Although biological treatment is a low-carbon and eco-friendly approach for TOPs degradation, its effectiveness is often limited by the high toxicity and recalcitrance of TOPs. Oxidative and reductive reactions can degrade TOPs according to their intrinsic redox potentials. However, conventional biological or chemical oxidation treatment often fails to efficiently or purposefully cleave key functional groups, which leads to unsatisfactory performance of biological reactions or excessive chemical oxidation costs. This perspective proposes redox regulation as a strategy to moderately catalyse the oxidation or reduction of TOPs and thereby generate low toxicity and increased biodegradable intermediates, which will improve subsequent biological treatment. We summarize strong redox regulation techniques, including advanced oxidation and reduction processes, and weak redox regulation through low-energy electrical potential, along with the corresponding mechanisms and applications. Additionally, we explore the integration of redox regulation with biological treatment, either in a sequential mode or in situ. This study emphasizes the need for future research to focus on targeted and durable catalytic detoxification processes and to optimize balancing the carbon footprint, process control, operational efficiency, and economic feasibility. By integrating chemical reactions with microbial metabolism, redox regulation has the potential to transform wastewater treatment from isolated process optimization to a holistic approach. This perspective advocates for innovation of conventional wastewater detoxification technologies to achieve sustainable water purification and ecological risk control.

As one of the typical emerging contaminants, microplastics exist widely in the environment because of their small size and recalcitrance, which has caused various ecological problems. This paper summarizes current adsorption and removal technologies of microplastics in typical aquatic environments, including natural freshwater, marine, drinking water treatment plants (DWTPs), and wastewater treatment plants (WWTPs), and includes abiotic and biotic degradation technologies as one of the removal technologies. Recently, numerous studies have shown that enrichment technologies have been widely used to remove microplastics in natural freshwater environments, DWTPs, and WWTPs. Efficient removal of microplastics via WWTPs is critical to reduce the release to the natural environment as a key connection point to prevent the transfer of microplastics from society to natural water systems. Photocatalytic technology has outstanding pre-degradation effects on microplastics, and the isolated microbial strains or enriched communities can degrade up to 50% or more of pre-processed microplastics. Thus, more research focusing on microplastic degradation could be carried out by combining physical and chemical pretreatment with subsequent microbial biodegradation. In addition, the current recovery technologies of microplastics are introduced in this review. This is incredibly challenging because of the small size and dispersibility of microplastics, and the related technologies still need further development. This paper will provide theoretical support and advice for preventing and controlling the ecological risks mediated by microplastics in the aquatic environment and share recommendations for future research on the removal and recovery of microplastics in various aquatic environments, including natural aquatic environments, DWTPs, and WWTPs.