The presence of newly emerging pollutants in the aquatic environment poses great challenges for drinking water treatment plants. Due to their low concentrations and unknown characteristics, emerging pollutants cannot be efficiently removed by conventional water treatment processes, making technically, economically, and environmentally friendly water purification technologies increasingly important. This article introduces a one-step reverse osmosis (OSRO) concept consisting of riverbank filtration (RBF) and reverse osmosis (RO) for drinking water treatment. The OSRO concept combines the relatively low-cost natural pretreatment of river water with an advanced engineered purification system. RBF provides a continuous natural source of water with stable water quality and a robust barrier for contaminants. With the pre-removal of particles, organic matter, organic micro-pollutants (OMPs), and microbes, RBF becomes an ideal source for a purification system based on RO membranes, in comparison with the direct intake of surface water. OSRO treatment removes almost 99.9% of the particles, pathogens, viruses, and OMPs, as well as the vast majority of nutrients, and thus meets the requirements for the chlorine-free delivery of drinking water with high biostability. The OSRO treatment is cost effective compared with the standard conventional series of purification steps involving sprinkling filters, softening, and activated carbon. Artificial bank filtration (ABF), which functions as an artificial recharge in combination with a sand filtration system, is proposed as an alternative for RBF in the OSRO concept to supply drinking water from locally available resources. It is also suggested that the OSRO concept be implemented with wind power as an alternative energy source in order to be more sustainable and renewable. An OSRO-based decentralized water system is proposed for water reclaiming and reuse. It is suggested that future water treatment focus on the combination of natural and engineered systems to provide drinking water through technically efficient, financially feasible, resource reusable, and environmentally relevant means.

Titanium dioxide nanoparticles (TiO₂ NPs) are widely used as nano-agrochemicals. In this study we investigated the influence of soil heterogeneity on bacterial communities exposed to TiO₂ NPs over time. Clay and sandy soils with low- and high-organic matter contents were exposed to environmentally relevant concentration of TiO₂ NPs (1 mg/kg) and soil bacterial communities were sampled after short-term (15 days) and long-term exposure (60 days). After short-term TiO₂ NPs exposure, significant effects regarding the enzyme activity, bacterial community structure and composition, and community functioning were observed in the clay soils with high organic matter (clay-HOM) but not in other soil groups. Response alterations were observed to taxa belonging to Acidobacteria and Verrucomicrobia, and functional pathways related to carbohydrates degradation. These results indicated that soil heterogeneity play more important roles in shaping the bacterial community in soil with low clay fraction and less organic matter, while TiO₂ NPs selection was the main driver in inducing the compositional and functional impacts on the soil bacterial community in the presence of clay soil with high organic matter content. As exposure time increased, the bacterial community recovered after a long-term exposure of 60 days, suggesting that the bacterial evolution and adaptation could overcome the TiO₂ NPs selection after long-term exposure. Our results highlighted the importance of soil heterogeneity including clay fraction and organic matter and exposure duration in assessing the impact of nanoparticle on soil bacterial activity, community and function. By comprehensively evaluating the risks of nanoparticles on soil ecosystem and explicitly and explicitly include spatial and temporal variations, the benefit of nano-agrochemical products has the potential to be promoted in future applications.

Titanium dioxide nanoparticles (TiO₂NP) are increasingly released in soil ecosystems, while there is limited understanding of the impacts of TiO₂NP on soil bacterial communities. Here we investigated the effects of TiO₂NP on the taxonomic composition and functional profile of a soil bacterial community over a 60-day exposure period. In short-term exposure (1-day), contradictory effects on the taxonomic composition of soil bacterial communities were found after exposure to a low realistic environmental concentration of TiO₂NP at 1 mg/kg as compared to the effects induced by medium and high concentrations of TiO₂NP at 500 and 2000 mg/kg. After long-term exposure (60-day), the negative effects of TiO₂NP at the low concentration disappeared, and the inhibition by TiO₂NP of the abundance of core taxa was enhanced along with increasing exposure concentrations. However, although significant alterations were observed in the taxonomic composition over time and exposure concentrations, no significant change was observed in the community functional profile as well as enzyme activity after 60-day exposure, indicating that functional redundancy likely contributed to the bacterial community tolerance after the exposure to TiO₂NP. Our study highlighted the importance of assessing bacterial community compositional and functional responses in assessing the environmental risk of nanoparticles on soil ecosystems.

Titanium dioxide nanoparticles (TiO₂NP) are often released into the soil through repeated discharge of wastewater and repetitive applications as fertilizers. Adverse effects of a single pulse on soil bacterial communities have been widely studied, while the impact of repeated exposure is poorly understood. This study compared the impacts of single and repeated exposure scenarios on the soil bacterial community. The repeated exposure promoted the total bacterial biomass but reduced the community diversity and induced larger alterations in community composition compared to the single exposure. Regarding the dosing frequencies of repeated exposure, community divergence increased in initial dosing cycles, and community stability was re-established and remained in subsequent dosing cycles. According to the different tolerance to dosing frequencies, the dynamic response patterns of the featured OTUs and functional genes could be classified into four types: 1) promotion, 2) suppression-recovery-promotion, 3) promotion-suppression-stable, and 4) suppression. These results suggest that chronic exposure with repetitive low-dosing of nanoparticles induced a tendency towards larger alteration of both community composition and functioning than in case of application of a single pulse of the same dosage. This study brings new insight into understanding the compositional and predicted functional dynamics of the soil bacterial community in response to nanoparticles and identifies a data gap in realistic time-variable exposure testing.