Riverbank filtration is a nature-based water treatment strategy known for its effective removal of organic micropollutants. Yet, the mechanisms governing their biodegradation, especially the role of redox transitions in mediating biotransformation, remain insufficiently understood. Here, we integrate metagenomic profiling with chemical analytics in a 10 m simulated riverbank filtration system to demonstrate how sequential oxidizing–reducing degradation enhances organic micropollutant transformation. Oxygen stratification structured distinct microbial and enzymatic pathways: oxidizing zones (>+200 mV redox potential) facilitated cytochrome P450-mediated oxidation (oxidizing condition, OXD), while subsequent redox shifts to reducing conditions (←400 mV, sequential oxidizing–reducing (SOR) conditions) activated reductive transformations (e.g., via nitronate monooxygenase and aldehyde dehydrogenase) and conjugation pathways. These SOR conditions significantly enhanced the removal of recalcitrant compounds, including irbesartan (+25.3%), benzotriazole (13.4%), and gabapentin (+9.7%). Metagenomic analysis revealed redox-driven microbial specialization, with Pseudomonadota and Nitrospirota dominating in oxidizing zones and reducing microzones enriched in pathways associated with nitrotoluene and ethylbenzene degradation, providing genomic evidence for sequential organic micropollutant breakdown. These findings establish a mechanistic framework for harnessing oxidizing–reducing microbial partnerships to amplify organic micropollutant removal in nature-based water treatment systems, which can be used for riverbank filtration site selection and well field construction and optimization.

Shower systems provide unique environments that are conducive to biofilm formation and the proliferation of pathogens. The water heating temperature is a delicate decision that can impact microbial growth, balancing safety and energy consumption. This study investigated the impact of different heating temperatures (39 °C, 45 °C, 51 °C and 58 °C) on the shower hose biofilm (exposed to a final water temperature of 39 °C) using controlled full-scale shower setups. Whole metagenome sequencing and metaproteomics were employed to unveil the microbial composition and protein expression profiles. Overall, the genes and enzymes associated with disinfectant resistance and biofilm formation appeared largely unaffected. However, metagenomic analysis revealed a sharp decline in the number of total (86,371 to 34,550) and unique genes (32,279 to 137) with the increase in hot water temperature, indicating a significant reduction of overall microbial complexity. None of the unique proteins were detected in the proteomics experiments, suggesting smaller variation among biofilms on the proteome level compared to genomic data. Furthermore, out of 43 pathogens detected by metagenomics, only 5 could actually be detected by metaproteomics. Most interestingly, our study indicates that 45 °C heating temperature may represent an optimal balance. It minimizes active biomass (ATP) and reduces the presence of pathogens while saving heating energy. Our study offered new insights into the impact of heating temperature on shower hose biofilm formation and proposed optimal parameters that ensure biosafety while conserving energy.

Recently, great efforts have been focused on solar evaporators because they can localize solar heat on the air-water interface resulting in enhanced photothermal conversion efficiency. However, to prevent salt accumulation during evaporation while maintaining high evaporation rates is still a challenge. In this work, a salt-rejecting solar evaporator was fabricated for continuous seawater desalination. The evaporator was composed of a top layer of carbon black (CB) nanoparticles for solar absorbance, an interlayer of superhydrophilic melamine formaldehyde (MF) foam for both seawater and concentrated brine delivery, and an outlayer of expandable polyethylene (EPE) foam for floating and heat insulation. The superhydrophilic MF foam could offer a channel for rapid exchange of the concentrated brine with the solution beneath, thereby preventing salt accumulation in the evaporator. It was demonstrated that the salt-rejecting solar evaporator produced a high water evaporation rate of 1.24 kg·m-2·h-1 under 1 kW·m-2 solar irradiance, which was 3.2 times higher than that of the pristine simulated seawater (3.5 wt% NaCl solution). Furthermore, the salt-rejecting evaporator displayed an excellent stability as the water evaporation rate remained constant even after 16-cycles of use within 20 days.