Salinity-mediated water self-purification via bond network distorting of H2O molecules on DRC-surface.

High salinity has plagued wastewater treatment for a long time by hindering pollutant removal, thereby becoming a global challenge for water pollution control that is difficult to overcome even with massive energy consumption. Herein, we propose a novel process for rapid salinity-mediated water self-purification in a dual-reaction-centers (DRC) system with cation-π structures. In this process, local hydrogen bond networks of H2O molecules can be distorted through the mediation of salinity, thereby opening the channels for the preferential contact of pollutants on the DRC interface. As the result, the elimination rate of pollutants increased approximately 32-fold at high salinity (100 mM) without any external energy consumption. Our findings provide a novel technology for high-efficiency and low-consumption water self-purification, which is of great significance in environmental remediation and even fine chemical industry.

Towards sustainable development goals: An analysis of environmental efficiency and the impacts of self-purification capacity across diverse income levels.

The increasing urgency of global environmental degradation, particularly across diverse economic development stages, underscores a critical need for nuanced understanding and targeted strategies to achieve Sustainable Development Goals. Our study examines environmental efficiency trends over 27 years in 163 countries, utilizing greenhouse gases and particulate matter 2.5 as indicators. We address the challenge by developing and applying a two-stage method that combines a hyperbolic distance function with a stochastic meta frontier approach to assess environmental meta-efficiency. The average meta efficiency of these countries is 0.464, which remains at a relatively low level. Our model indicates that the high-income country group needs to reduce greenhouse gas and pollutant emissions by 25% and increase non-fossil energy usage by 33% to improve environmental efficiency. This suggests these countries must transition towards more sustainable energy sources and practices. Moreover, recognizing that existing income grouping inadequately characterizes each country, we use k-means cluster analysis for regrouping, more accurately reflecting individual differences. The regrouping results show that some high-income countries are classified into inactive groups, implying serious environmental problems. Our findings advocate for collaborative and tailored strategies to address these disparities. We conclude that income levels cannot solely drive environmental efficiency but must also consider geographical and climatic factors, which are pivotal in shaping a country's environmental policies and efforts. This approach offers a clearer understanding of current inefficiencies and sets the stage for more informed policy-making that can better address the specific needs and capabilities of different countries.

Water Self-Purification with Zero External Consumption by Livestock Manure Resource Utilization.

Improper disposal of waste biomass and an increasing number of emerging contaminants (ECs) in water environment are universal threats to the global environment. Here, we creatively propose a sustainable strategy for the direct resource transformation of livestock manure (LM) into an innovative catalyst (Fe-CCM) for water self-purification with zero external consumption. ECs can be rapidly degraded in this self-purification system at ambient temperature and atmospheric pressure, without any external oxidants or energy input, accompanied by H2O and dissolved oxygen (DO) activation. The performance of the self-purification system is not affected by various types of salinity in the wastewater, and the corresponding second-order kinetic constant is improved 7 times. The enhanced water self-purification mechanism reveales that intermolecular forces between anions and pollutants reinforce electron exchange between pollutants and metal sites on the catalyst, further inducing the utilization of the intrinsic energy of contaminants, H2O, and DO through the interfacial reaction. This work provides new insights into the rapid removal of ECs in complicated water systems with zero external consumption and is expected to advance the resource utilization of livestock waste.

A method of gas-related pollution source layout based on multi-source data: A case study of shaanxi province, China.

The location and layout of enterprises have an important impact on local air quality. However, a few studies on exploring of the optimal layout of gas-related enterprises from the perspective of optimizing the layout of air pollution sources. This study developed a method for the evaluation of air pollution source layout based on air pollutant emission inventory data, atmospheric self-purification capacity data, and satellite remote sensing air quality data. Taking Shaanxi Province as an example, the Moran's I index and GIS spatial analysis techniques were used to evaluate the layout of air pollution sources, analyze the spatial variation characteristics of air pollution sources, and propose specific countermeasures to optimize the layout of air pollution sources. Results showed that northern Shaanxi and Guanzhong Plain are the most unsuitable for the distribution of NOx and CO sources, accounting for 13.78% and 21.77% of the total area, respectively. The most suitable area for the distribution of NOx is southern Shaanxi, accounting for 65.77% of the total area, mainly concentrated in Hanzhong and Ankang regions. The most suitable area for the distribution of CO is southern Shaanxi, accounting for 40.97% of the total area, mainly concentrated in Hanzhong and Shangluo regions. The findings of this study could supplement and improve the evaluation of the layout of industrial enterprises in China from technical and methodological aspects, and provide new insight for local governments to adjust and optimize the layout of air pollution sources.

Preferential Destruction of Micropollutants in Water through a Self-Purification Process with Dissolved Organic Carbon Polar Complexation.

Removing micropollutants in real water is a scientific challenge due to primary dissolved organic carbon (DOC) and high energy consumption of current technologies. Herein, we develop a self-purification process for the preferential destruction of various micropollutants in municipal wastewater, raw drinking water, and ultrapure water with humic acid (HA) driven by the surface microelectronic field of Fe0-FeyCz/Fex-GZIF-8-rGO without any additional input. It was verified that a strongly polar complex consisting of an electron-rich HA/DOC area and an electron-poor micropollutant area was formed between HA/DOC and micropollutants, promoting more electrons of micropollutants in the adsorbed complex to delocalizing to electron-rich Fe species area and be trapped by O2, which resulted in their surface cleavage and hydrolyzation preferentially. The higher micropollutant degradation efficiency observed in real wastewaters was due to the greater complex polarity of DOC. Moreover, the electron transfer process ensured the stability of the surface microelectronic field and continuous water purification. Our findings provide a new insight into low-energy combined-micropollution water treatment.

Storage tank as a pretreatment unit for rainwater cleaner production: Role of biofilm bacterial communities and functional genera in water quality improvement.

This study investigated the water purification function and mechanism of biofilm in storage tank, with a view to using it as a pretreatment unit for rainwater cleaner production. Shortening the hydraulic retention time (HRT) of storage tank from 12 to 4 h improved the pollutants removal performance and reduced the suspended bacteria counts. The accumulation of abundant taxa and succession of rare taxa were observed with biofilm development. Positive correlations within and across different bacterial taxa were dominant in the network, and some rare genera (Ralstonia and Micropruina) were identified as hub bacteria. Candidatus Nitrospira nitrosa and Nitrospira sp. ENR4 were two identified complete ammonia oxidizers. Denitrifying bacteria tended to enrich and formed more complex interactions over time. The main nitrogen metabolism pathways may be ammonia assimilatory, complete denitrification and dissimilatory/assimilatory nitrate reduction. HRT was negatively correlated with most dominant genera, and contributed 20.35% to the variation of functional taxa. This study highlights the self-purification function and micro-ecology of storage tank, and provides a new insight for its role in rainwater cleaner production process.

Circling the drain: A systems analysis of opportunities for enhanced sewer self-purification technologies in wastewater management.

The shift of discussions on wastewater management to realize a circular water economy requires rethinking of how the existing systems are managed. The collection system, a physical infrastructure that collects and transports wastewater, is often overlooked in innovation studies in wastewater management. Hence, a review of the collection system is required to realize overlooked innovation points, especially those of its functions and configurations. In this paper, we highlight the possibility of the collection system to contribute to wastewater management, not only to collect and transport wastewater, but to treat wastewater through enhancing sewer self-purification. To realize this, a systems analysis of the forms and functions of the collection system was first conducted to see how the collection system supports different wastewater management systems. It was found that emphasis on the collection system's function to treat wastewater is beneficial because of the transition of wastewater management towards a circular water economy. Second, a scenario analysis of applying enhanced sewer self-purification technologies was conducted to determine communities which would most benefit from using the collection system to treat wastewater. The findings highlight that communities with as much as 100 cap ha-1, typical of urban peripheries, could have their pollutant load reduced to about half if the pipe length per capita is 5 m. It was seen in this study that while the collection system supports wastewater management by functioning to collect and transport wastewater, it can further be elevated into a treatment technology within appropriate localities and thus, contribute to a circular water economy.

Sustainable ecological engineering systems for the treatment of domestic wastewater using emerging, floating and submerged macrophytes.

Water scarcity is perceived as a global systemic risk since there is an inexorable rise in water demand. An ecological engineering system mimics a natural ecosystem by balancing the trophic conditions for effective treatment of wastewater in a sequential manner. The present study was designed using emergent, floating and submerged macrophytic plants in a systematic approach. The study was evaluated with several components such as plants (water hyacinth, water lettuce and water thymes), aeration (supply of oxygen), and physical adsorption (activated carbon). Domestic wastewater collected from the local effluent treatment plant was treated individually and by combining all the components. Diverse experimental setups viz., lake sediment (control reactor), aeration, activated carbon blocks, water hyacinth, water lettuce, and water thymes were individually studied. Further the above components were combined, such as lake sediment + aeration + activated carbon blocks with plants like water hyacinth, water lettuce, and water thymes. The study inferred along with phytoremediation, and the external factors enhanced the treatment performances. Water hyacinth documented enhanced chemical oxygen demand removal efficiency of 85.71%, followed by water lettuce (80%), and water thymes (77.14%) along with the plants, both aeration, and activated carbon had stimulated the wastewater treatment. The highest removal efficiency of nitrate (70.23%), phosphate (63.64%), and sulphate (61.16%) were observed in water hyacinth due to its thick roots, and fibrous tissues reported effective treatment. The study hypothesized that these processes could be an effective strategy to restore the lakes and regulate the environmental flow. The study infers that an ecological engineering system symbiotically enables to self-organize the ecosystem within the boundary.

Intrinsic Ferromagnetism in Mn-Substituted MoS2 Nanosheets Achieved by Supercritical Hydrothermal Reaction.

Doping atomically thick nanosheets is a great challenge due to the self-purification effect that drives the precipitation of dopants. Here, a breakthrough is made to dope Mn atoms substitutionally into MoS2 nanosheets in a sulfur-rich supercritical hydrothermal reaction environment, where the formation energy of Mn substituting for Mo sites in MoS2 is significantly reduced to overcome the self-purification effect. The substitutional Mn doping is convincingly evidenced by high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine spectroscopy characterizations. The Mn-doped MoS2 nanosheets show robust intrinsic ferromagnetic response with a saturation magnetic moment of 0.05 µB Mn-1 at room temperature. The intrinsic ferromagnetism is further confirmed by the reversibility of the magnetic behavior during the cycle of incorporating/removing Li codopants, showing the critical role of Mn 3d electronic states in mediating the magnetic interactions in MoS2 nanosheets.

Role of clusters in nonclassical nucleation and growth of protein crystals.

The development of multistep nucleation theory has spurred on experimentalists to find intermediate metastable states that are relevant to the solidification pathway of the molecule under interest. A great deal of studies focused on characterizing the so-called "precritical clusters" that may arise in the precipitation process. However, in macromolecular systems, the role that these clusters might play in the nucleation process and in the second stage of the precipitation process, i.e., growth, remains to a great extent unknown. Therefore, using biological macromolecules as a model system, we have studied the mesoscopic intermediate, the solid end state, and the relationship that exists between them. We present experimental evidence that these clusters are liquid-like and stable with respect to the parent liquid and metastable compared with the emerging crystalline phase. The presence of these clusters in the bulk liquid is associated with a nonclassical mechanism of crystal growth and can trigger a self-purifying cascade of impurity-poisoned crystal surfaces. These observations demonstrate that there exists a nontrivial connection between the growth of the macroscopic crystalline phase and the mesoscopic intermediate which should not be ignored. On the other hand, our experimental data also show that clusters existing in protein solutions can significantly increase the nucleation rate and therefore play a relevant role in the nucleation process.

Impact of Tannery Effluent on the Self-purification Capacity and Biodiversity Level of a River.

The present study investigates the impact of tannery effluents on the self-purification capacity and the local macroinvertebrate community of one natural stream. As the concentration of chromium and sulfide increased from up- to downstream sites, the reduction of suspended solids, 5-days biological oxygen demand (BOD5), chemical oxygen demand and nitrification capacity decreased by 61 %, 21 %, 30 % and 74 %, respectively. Similarly, the share of Ephemeroptera, Plecoptera, and Trichoptera on the macroinvertebrate community decreased from 24 % to 0 %. Also the diversity (Simpson's) index and the correlation between the physicochemical parameters, BOD5 reduction, the macroinvertebrate abundance and the chromium concentration underpin the importance of the contamination by tannery effluents for the degradation of the stream habitat quality. In conclusion, although the physicochemical parameters indicate that the self-purification of the river can be maintained for a certain stream section, the biodiversity of the river is severely compromised.

Mapping the profiles and underlying driving mechanisms of the antibiotic resistome and microbiome within a subtropical complex river watershed.

Antibiotic resistance is an escalating global concern, leading to millions of annual deaths worldwide. Human activities can impact antibiotic resistance gene (ARG) prevalence in aquatic ecosystems, but the intricate interplay between anthropogenic disturbances and river system resilience, and their respective contributions to the dynamics of different river segments, remains poorly understood. In this study, we investigate the antibiotic resistome and microbiome in water and sediment samples from two distinct sub-watersheds within a specific watershed. Results show a decrease in the number of core ARGs downstream in water, while sediments near densely populated areas exhibit an increase. PCoA ordination reveals clear geographic clustering of resistome and microbiome among samples from strong anthropogenic disturbed areas, reservoir areas, and estuary area. Co-occurrence networks highlight a higher connectivity of mobile genetic elements (MGEs) in disturbed areas compared to reservoir areas, presenting a threat to densely populated areas. Water quality parameters and antibiotics concentration were the key factors shaping the ARG profiles in sediment samples from urban regions. Overall, our study reveals distinct patterns of ARGs in sediment and water samples, emphasizing the importance of considering both anthropogenic and natural factors in comprehending and managing ARG distribution in river systems.

Bioinspired BSA@polydopamine@Fe Nanoprobe with Self-Purification Capacity for Targeted Magnetic Resonance Imaging of Acute Kidney Injury.

Contrast-enhanced magnetic resonance imaging (CE-MRI) of acute kidney injury (AKI) is severely hindered by the poor targeting capacity and potential toxicity of current contrast agents. Herein, we propose one-step fabrication of a bovine serum albumin@polydopamine@Fe (BSA@PDA@Fe, BPFe) nanoprobe with self-purification capacity for targeted CE-MRI of AKI. BSA endows the BPFe nanoprobe with renal tubule-targeting ability, and PDA is capable of completely inhibiting the intrinsic metal-induced reactive oxygen species (ROS), which are always involved in Fe/Mn-based agents. The as-prepared nanoprobe owns a tiny size of 2.7 nm, excellent solubility, good T1 MRI ability, superior biocompatibility, and powerful antioxidant capacity. In vivo CE-MRI shows that the BPFe nanoprobe can accumulate in the renal cortex due to the reabsorption effect toward the serum albumin. In the AKI model, impaired renal reabsorption function can be effortlessly detected via the diminishment of renal cortical signal enhancement. More importantly, the administration of the BPFe nanoprobe would not aggravate renal damage of AKI due to the outstanding self-purification capacity. Besides, the BPFe nanoprobe is employed for CE-MR angiography to visualize fine vessel structures. This work provides an MRI contrast agent with good biosafety and targeting ability for CE-MRI of kidney diseases.

Water self-purification via electron donation effect of emerging contaminants arousing oxygen activation over ordered carbon-enhanced CoFe quantum dots.

The release of emerging contaminants (ECs) into aquatic environments poses a significant risk to global water security. Advanced oxidation processes (AOPs), while effective in removing ECs, are often resource and energy-intensive. Here, we introduce a novel catalyst, CoFe quantum dots embedded in graphene nanowires (CoFeQds@GN-Nws), synthesized through anaerobic polymerization. It uniquely features electron-rich and electron-poor micro-regions on its surface, enabling a self-purification mechanism in wastewater. This is achieved by harnessing the internal energy of wastewater, particularly the bonding energy of pollutants and dissolved oxygen (DO). It demonstrates exceptional efficiency in removing ECs at ambient temperature and pressure without the need for external oxidants, achieving a removal rate of nearly 100.0%. The catalyst's structure-activity relationship reveals that CoFe quantum dots facilitate an unbalanced electron distribution, forming these micro-regions. This leads to a continuous electron-donation effect, where pollutants are effectively cleaved or oxidized. Concurrently, DO is activated into superoxide anions (O2•-), synergistically aiding in pollutant removal. This approach reduces resource and energy demands typically associated with AOPs, marking a sustainable advancement in wastewater treatment technologies.

Mechanism of sinuosity effect on self-purification capacity of rivers.

As one of the important characteristics of river morphology, river sinuosity has a direct impact on the river water quality and self-purification capacity. In the present study, 4 physical river channel simulation models using circulating water with a sinuosity of 2.2, 1.8, 1.4, and 1.0, respectively, were established in our laboratory. Related hydraulic tests and detection were performed, including the detection of microbial communities in overlying water, monitoring of the river flow velocity and depth, and observation of the river flow line and bank scouring. The results show that the TN reduction rate at a sinuosity of 2.2 was 1.09, 1.20, and 1.75 times that at a sinuosity of 1.8, 1.4, and 1.0, respectively. And the total plate count for the set of tests with a sinuosity of 2.2 was 3.32 times that for the set of tests with a straight channel. The sinuous rivers have more complex flow regimes, more suitable hydraulic conditions, larger hyporheic zone areas, better microbial environments, and longer river flow paths, giving them a higher purification capacity against pollution. These findings can provide a theoretical basis for the optimization of water system layout and the restoration of river environments in the process of urbanization in China.

Estimation of the capacity for self-purification of transformed rivers of Khanty-Mansi Autonomous Okrug-Yugra (Russia).

This article presents an estimation of the self-purification capacity of rivers flowing through an area of the Ob River basin at Khanty-Mansi Autonomous Okrug-Yugra, which has been significantly transformed by the oil and gas industry. The research was done on the rivers of the Ob River basin in oil fields in 2003-2006 and 2018-2019. The coefficient of mineralization of organic matter has been used as a criterion of the rivers' water self-purification levels. The mineralization coefficient was based on the ratio of numbers of bacteria consuming ammonium nitrogen and polymer substances as well as saprophytic heterotrophic bacteria. According to the results obtained, most rivers draining the oil field area (75% in 2003-2006 and 79% in 2018-2019) were characterized by a low potential for self-purification. The highest level of self-purification criteria was obtained for two rivers: the Ai-Pim River in the Surgut region and the Ovyn'yegan River in the Oktyabrsky region. The high level of self-purification detected with the coeficient of mineralization ensures the maintenance of a certain trophical level and environmental balance of the aquatic ecosystem. Complicated technological processes applied in the oil and gas industry, as well as outdated equipment and poor environmental management, often lead to pipeline accidents and other infrastructure failures. Hazardous pollutants flow into rivers from the watershed area and further into the Gulf of Ob of the Kara Sea. Continuous monitoring of water quality and water resource management based on the results obtained will constitute serious measures to prevent deterioration of aquatic ecosystems. It is necessary to include microbiological parameters in monitoring programs, as this helps to identify the processes of transformation of chemicals found in the river. The use of self-purification assessment methodology for rivers in oil field areas yields effective results in the decision-making process in the sphere of water resource management, significantly reducing ecological risks in the Ob River basin and, as a consequence, in the Arctic region. Integr Environ Assess Manag 2023;19:988-993. © 2022 SETAC.

Introduction to the Special Series "Environmental Monitoring on Global and Local Scales".

The ecosystems of Siberia provide valuable services to the human population and afford important climate feedback. However, they are subject to anthropogenic pressures leading to the transformation of ecosystem structure and functions such as deforestation; extraction and transportation of fossil hydrocarbons; mining, refining, and smelting industrial activities; damming of rivers by high-pressure hydroelectric plants, and other activities. The articles in this special series deal with the monitoring of natural ecosystems of Siberia that are located on vast areas of Eurasia, many of which are hard to reach and sparsely populated. The results and approaches of environmental monitoring presented in this special series offer new opportunities for developing the strategy of intelligent management and conservation of vulnerable Siberian ecosystems to meet the challenges of global climate change and unsustainable use of natural resources. Integr Environ Assess Manag 2023;19:970-971. © 2023 SETAC.

Variations of different PAH fractions and bacterial communities during the biological self-purification in the soil vertical profile.

Wild PAH-contaminated sites struggle to provide continuous and stable monitoring, resulting in the potential risks of contaminated soil utilization could not be evaluated effectively. This work provided a 9-months laboratory simulation which was close to the natural ecological process. These results believed that PAH-degrading bacteria (PDB) preferred to degrade organic extracted PAH (PAH_OS) and fresh bound-PAH (79.36-99.97%). The formation and migration efficiency of PAH binding with HA humic acid (HA) (PAH_HA) was lower than that of PAH binding with fulvic acid (FA) and humin (HM) (PAH_FA and PAH_HM), leading to PAH_HA had more persistent retention and influenced bacterial communities in shallow soils. Besides, phylum Proteobacteria gradually dominated the bacterial community and decreased 12.05-20.48% diversity at all depths during the biological self-purification process. Although the effect of this process enhanced the abundance of 28 genes 16 s rRNA and three PAH-degrading genes (PDGs) by 5.91-2047.34 times (phe, nahAc and nidA), the top 30 genera maintained their ecological characteristics. This study provided insights into the important influencing factor and mechanism of the biological self-purification processes and discerned the linkages between bacterial communities and environmental variables in the vertical profile, which is important to the isolation and application of PDB and ecological risk assessment.

Model of Phytoplankton Diversity in Belawan River, North Sumatera, Indonesia.

<b>Background and Objective:</b> Belawan River is located in Deli Serdang and Medan Districts, North Sumatra, Indonesia. Belawan River passes through residential areas, industry, steam power plants (PLTU), PDAM and encroachment. Waste is directly discharged into water bodies due to many human activities, so the quality of water and aquatic biota is disturbed. Phytoplankton diversity is influenced by water quality conditions because its existence depends heavily on the water conditions of the Belawan River. Analyzing the model of phytoplankton diversity in the Belawan River was the purpose of this study. <b>Materials and Methods:</b> The analysis was conducted in the form of phytoplankton diversity by obtaining phytoplankton species and their distribution and analyze the environment such as the water quality of the Belawan River. Sampling was taken by purposive random method with 5 different locations with 3 times the test with, namely starting from the upstream, middle and downstream Belawan River area in 2010, 2015 and 2020. Stages of research methods, obtained types of plankton, abundance (A), relative abundance (RA), presence frequency (PF), equitability (E) and diversity (H) and analysis of water quality (temperature, light penetration, light intensity, depth, current speed, salinity, pH, DO, oxygen saturation percent, BOD and COD). <b>Results:</b> Twenty three genera of phytoplankton were found in 2020. Phytoplankton abundance was highest in the <i>Chaetoceros</i> sp., genera with an abundance of 186 ind m² at station 5. Diversity (H) was highest at station 5 at 2.30 and lowest at station 5 at 1.87. Phytoplankton in five stations was relatively low. The DO has a very strong effect on phytoplankton's diversity. The model of phytoplankton diversity relationship with water quality is y = -2.09235475-0.283821248x₁-0.000034042331x₂²-0.000000317192297x₃²+ 0.0000138747473x₄²-0.0642412267x₅²+0.0436398590x₆-0.0107999363x₇²+0.0000469016376x₈². <b>Conclusion:</b> Dissolved oxygen (DO) has an effect on the diversity of phytoplankton in the Belawan River where the highest phytoplankton is <i>Chaetoceros</i> sp., of 23 genera which was found with a diversity value of 2.30 at station V.

Numerical investigation of pollution transport around a single non-submerged spur dike.

Industrial contaminants and chemicals adversely impact surface water quality and may lead to serious health risks to human and ecosystems. Rivers as one of the major surface water resources receive wastewaters and transport dissolved pollutions in water through Advection-Dispersion processes. A minimum distance known as the mixing length is required for complete mixing and dispersion of the pollutants. Since the concentration of pollutants often exceeds the self-purification capacity of rivers within this distance, reducing it decreases the negative impacts on the aquatic ecosystems. Creating turbulent flows with inherent mixing characteristics is an efficient measure in decreasing the mixing length. Spur dikes that are widely used in river engineering are able to reduce the mixing length by virtue of the turbulence made in a stream. Given the fact that entry of pollutants into the surface water is inevitable and the influence of spur dikes on the characteristics of pollution transport has not been meticulously investigated, this study aimed at the numerical simulation of pollution transport in a rectangular channel adjacent to a spur dike. We thus invoked Flow-3D to simulate flow and transport characteristics around an impermeable and non-submerged rectangular spur dike. The findings of this study enhance our understanding of spur dike effects on pollution transport. Notwithstanding the fact that the spur dike effectively decreased the mixing length of the pollution, the location of the pollutant entry also played a prominent role in reducing the length of this region.