Uncovering the evolution of tin use in the United States and its implications

• US tin use decreases as the GDP value added by manufacturing sector increases. • Global and China’s tin use increases as the GDP added by manufacturing increases. • A sigmoid curve can fit the US tin use data well. • US tin use patterns is not due to the finite tin reserves or resources. • Policies, substitutions, etc. play key roles in the changing tin use patterns. Tin is of key importance to daily life and national security; it is considered an essential industrial metal. The United States (US) is the world’s largest economy and consumer of natural resources. Therefore, the analysis of historical tin use in the US is helpful for understanding future tin use trends in the world as a whole and in developing countries. Time series analysis, regression analysis with GDP or GDP/capita, and historical data fitted with logistic and Gompertz models are employed in this study. Historical tin use in the US shows three stages—increase-constant-decrease, as GDP per capita has increased. Tin use in the US is negatively correlated with the GDP value added by the manufacturing sector, while the use of tin worldwide and in China continues to increase along with the GDP value added by the manufacturing sector. Although a sigmoid curve can fit the US tin use data well, that use is not directly related to the limited tin reserves or resources. Rather, policies, economic restructuring, substitutions, new end-use markets, etc. have played key roles in the changing tin use patterns. This work contributes to understanding future tin use at both the global and national levels: tin use will continue to increase with GDP at the global level, but use patterns of tin at the national level can be changed through human intervention.     

Nutrient status and pollution levels in five areas around a manganese mine in southern China

• The soil TP level was high or extremely high in all areas. • TN, OM and available Cu were insufficient in EA, TA and RA. • All areas reached the heavily polluted level and had high ecological risk levels. • Mn and Cd were the dominant pollutants. Nutrient status and pollution levels are the main factors affecting soil restoration. The nutrient status and pollution levels in five areas, an unexplored mine area (UA), an explored mine area (EA), a tailings area (TA), a reclamation area (RA) and an agricultural area (AA), around the Pingle manganese mine in Guangxi, China, were assessed in this study. The results showed that the average total phosphorus in these five areas ranged from 1.05 to 1.57 mg/kg, corresponding to grades of extremely high and high. The average total nitrogen values were 0.19, 0.69, 0.93, 1.24 and 1.67 mg/kg in EA, TA, RA, UA and AA, corresponding to grades of very low, low, medium-low, medium-high and medium-high, respectively. The average organic matter values were 12.78, 8.92, 22.77, 21.29 and 29.11 mg/kg in EA, TA, RA, UA and AA, which corresponded to grades of medium-low, low, medium-high, medium-high and medium-high, respectively. All these results indicated that the total phosphorus was sufficient in these areas, while the total nitrogen and organic matter were insufficient in EA, TA and RA. The available concentrations of Mn and Zn corresponded to the intermediate grade, while the values for Cu corresponded to the very low grade; these might be another factor restricting ecological reclamation. Contamination and ecological risk assessments based on the single contamination index, Nemerow multi-factor index and potential ecological risk index showed that the five tested areas around the Mn mine were considered heavily polluted and presented high ecological risk. Mn and Cd were the dominant pollutants.     

The combined effects of biomass and temperature on maximum specific ammonia oxidation rate in domestic wastewater treatment

• Actual SAORs was determined using MLVSS and temperature. • Measured SAOR decreased with increasing MLVSS 1.1‒8.7 g/L. • Temperature coefficient (θ) decreased with increasing MLVSS. • Nitrification process was dynamically simulated based on laboratory-scale SBR tests. • A modified model was successfully validated in pilot-scale SBR systems. Measurement and predicted variations of ammonia oxidation rate (AOR) are critical for the optimization of biological nitrogen removal, however, it is difficult to predict accurate AOR based on current models. In this study, a modified model was developed to predict AOR based on laboratory-scale tests and verified through pilot-scale tests. In biological nitrogen removal reactors, the specific ammonia oxidation rate (SAOR) was affected by both mixed liquor volatile suspended solids (MLVSS) concentration and temperature. When MLVSS increased 1.6, 4.2, and 7.1-fold (1.3‒8.9 g/L, at 20°C), the measured SAOR decreased by 21%, 49%, and 56%, respectively. Thereby, the estimated SAOR was suggested to modify when MLVSS changed through a power equation fitting. In addition, temperature coefficient (θ) was modified based on MLVSS concentration. These results suggested that the prediction of variations ammonia oxidation rate in real wastewater treatment system could be more accurate when considering the effect of MLVSS variations on SAOR.     

Synergistic effects of sodium hypochlorite disinfection and iron-oxidizing bacteria on early corrosion in cast iron pipes

• The early corrosion process in the cast iron pipes was investigated. • The increase of NaOCl (<0.75 mg/L) accelerated the cast iron corrosion. • Biocorrosion caused by IOB could be divided into three stages in the early stage. • Synergistic and antagonistic effects exist between residual chlorine and IOB. Corrosion in drinking water distribution systems (DWDSs) may lead to pipe failures and water quality deterioration; biocorrosion is the most common type. Chlorine disinfectants are widely used in DWDSs to inhibit microorganism growth, but these also promote electrochemical corrosion to a certain extent. This study explored the independent and synergistic effects of chlorine and microorganisms on pipeline corrosion. Sodium hypochlorite (NaOCl) at different concentrations (0, 0.25, 0.50, and 0.75 mg/L) and iron-oxidizing bacteria (IOB) were added to the reaction system, and a biofilm annular reactor (BAR) was employed to simulate operational water supply pipes and explain the composite effects. The degree of corrosion became severe with increasing NaOCl dosage. IOB accelerated the corrosion rate at an early stage, after which the reaction system gradually stabilized. When NaOCl and IOB existed together in the BAR, both synergistic and antagonistic effects occurred during the corrosion process. The AOC content increased due to the addition of NaOCl, which is conducive to bacterial regrowth. However, biofilm on cast iron coupons was greatly influenced by the disinfectant, leading to a decrease in microbial biomass over time. More research is needed to provide guidelines for pipeline corrosion control.     

Co-present Pb(II) accelerates the oxidation of organic contaminants by permanganate: Role of Pb(III)

• Simultaneous removal of organic contaminants and Pb(II) was achieved by Mn(VII). • Pb(II) enhanced Mn(VII) oxidation performance over a wide pH range. • Pb(II) did not alter the pH-rate profile for contaminants oxidation by Mn(VII). • Mn(VII) alone cannot oxidize Pb(II) effectively at pH below 5.0. • Pb(III) plays important roles on enhancing Mn(VII) decontamination process. The permanganate (Mn(VII)) oxidation has emerged as a promising technology for the remediation and treatment of the groundwater and surface water contaminated with the organic compounds. Nonetheless, only a few studies have been conducted to explore the role of the heavy metals (especially the redox-active ones) during the Mn(VII) oxidation process. In this study, taking Pb(II) as an example, its influence on the Mn(VII) decontamination performance has been extensively investigated. It was found that, with the presence of Pb(II), Mn(VII) could degrade diclofenac (DCF), 2,4-dichlorophenol, and aniline more effectively than without. For instance, over a wide pH range of 4.5–8.0, the dosing of 10 μmol/L Pb(II) accelerated the DCF removal rate from 0.006–0.25 min⁻¹ to 0.05–0.46 min⁻¹ with a promotion factor of 1.9–9.4. Although the UV-vis spectroscopic and high resolution transmission electron microscopy analyses suggested that Mn(VII) could react with Pb(II) to produce Mn(IV) and Pb(IV) at pH 6.0–8.0, further experiments revealed that Pb(II) did not exert its enhancing effect through promoting the generation of MnO₂, as the reactivity of MnO₂ was poor under the employed pH range. At pH below 5.0, it was interesting to find that, a negligible amount of MnO₂ was formed in the Mn(VII)/Pb(II) system in the absence of contaminants, while once MnO₂ was generated in the presence of contaminants, it could catalyze the Pb(II) oxidation to Pb(IV) by Mn(VII). Collectively, by highlighting the conversion process of Pb(II) to Pb(IV) by either Mn(VII) or MnO₂, the reactive Pb(III) intermediates were proposed to account for the Pb(II) enhancement effect.     

UV-LED/P25-based photocatalysis for effective degradation of isothiazolone biocide

• UV-LED with shorter wavelength was beneficial for photocatalytic degradation. • SRNOM dramatically inhibit the degradation. • ·OH acts as the active radical in photocatalytic degradation. • Degradation mainly undergoes oxidation, hydrolysis and chain growth reactions. In this work, LED-based photocatalysis using mixed rutile and anatase phase TiO₂ (P25) as the photocatalyst could effectively remove 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and methylisothiazolone (MIT) simultaneously, with removal efficiencies above 80% within 20 min. The photocatalytic degradation of both CMIT and MIT could be modeled using a pseudo-first-order rate equation. The photocatalytic degradation rates of CMIT and MIT under LED280 illumination were higher than under LED310 or LED360 illumination. At concentrations below 100 mg/L, the degradation rate of CMIT and MIT under LED illumination significantly increased with increasing catalyst dosage. Additionally, the effects of the chloride ion concentration, alkalinity and dissolved organic matter on the photocatalytic degradation reaction were also investigated. The ·OH free radicals were determined to play the primary role in the photocatalytic degradation reaction, with a degradation contribution of >95%. The photocatalytic degradation of CMIT and MIT mainly occurred via oxidation, hydrolysis, and chain growth reactions. Finally, the possible photocatalytic degradation pathways of CMIT and MIT over LED/P25 are proposed.     

Composition,dispersion, and health risks of bioaerosols in wastewater treatment plants: A review

• Bioaerosols are produced in the process of wastewater biological treatment. • The concentration of bioaerosol indoor is higher than outdoor. • Bioaerosols contain large amounts of potentially pathogenic biomass and chemicals. • Inhalation is the main route of exposure of bioaerosol. • Both the workers and the surrounding residents will be affected by the bioaerosol. Bioaerosols are defined as airborne particles (0.05–100 mm in size) of biological origin. They are considered potentially harmful to human health as they can contain pathogens such as bacteria, fungi, and viruses. This review summarizes the most recent research on the health risks of bioaerosols emitted from wastewater treatment plants (WWTPs) in order to improve the control of such bioaerosols. The concentration and size distribution of WWTP bioaerosols; their major emission sources, composition, and health risks; and considerations for future research are discussed. The major themes and findings in the literature are as follows: the major emission sources of WWTP bioaerosols include screen rooms, sludge-dewatering rooms, and aeration tanks; the bioaerosol concentrations in screen and sludge-dewatering rooms are higher than those outdoors. WWTP bioaerosols contain a variety of potentially pathogenic bacteria, fungi, antibiotic resistance genes, viruses, endotoxins, and toxic metal(loid)s. These potentially pathogenic substances spread with the bioaerosols, thereby posing health risks to workers and residents in and around the WWTP. Inhalation has been identified as the main exposure route, and children are at a higher risk of this than adults. Future studies should identify emerging contaminants, establish health risk assessments, and develop prevention and control systems.     

Product identification and toxicity change during oxidation of methotrexate by ferrate and permanganate in water

• Oxidation of methotrexate by high-valent metal-oxo species was first explored. • Fe(VI) presented a higher reactivity to MTX than Mn(VII) at pH 8.0. • Ketonization and cleavage of peptide bond were two initial reaction pathways. • Products of MTX were not genotoxic, neurotoxic, or endocrine-disrupting chemicals. • The less biodegradable products exhibited developmental and acute/chronic toxicity. Accompanying an annual increase in cancer incidence, the global use of anticancer drugs has remarkably increased with their worldwide environmental prevalence and ecological risks. In this study, the oxidation of methotrexate (MTX), a typical anticancer drug with ubiquitous occurrence and multi-endpoint toxicity, by ferrate(VI) (Fe(VI)) and permanganate (Mn(VII))) was investigated in water. Fe(VI) exhibited a higher reactivity with MTX (93.34 M⁻¹ s⁻¹) than Mn(VII) (3.01 M⁻¹ s⁻¹) at pH 8.0. The introduction of Cu(II) and Fe(III) at 1.0 mM improved the removal efficiency of 5.0 μM MTX by 100.0 μM Fe(VI) from 80% to 95% and 100% after 4 min, respectively. Seven oxidized products (OPs) were identified during oxidative treatments, while OP-191 and OP-205 were characterized as specific products for Fe(VI) oxidation. Initial ketonization of the L-glutamic acid moiety and cleavage of the peptide bond of MTX were proposed. Additionally, a multi-endpoint toxicity evaluation indicated no genotoxicity, neurotoxicity, or endocrine-disrupting effects of MTX and its OPs. Particularly, serious developmental toxicity in zebrafish larvae was observed in the treated MTX solutions. Based on the acute and chronic aquatic toxicity prediction, OP-190, OP-192, OP-206, and OP-208 were deemed toxic or very toxic compared to harmful MTX. Furthermore, the reduced biodegradability index from 0.15 (MTX) to −0.5 to −0.2 (OP-192, OP-206, and OP-468) indicated the formation of lower biodegradable OPs. Overall, this study suggests that Fe(VI) and Mn(VII) oxidation are promising treatments for remediating anticancer drug-contaminated water. However, the environmental risks associated with these treatments should be considered in the evaluation of water safety.     

Bioinspired cellulose-based membranes in oily wastewater treatment

• Cellulose-based membrane separates oily wastewater mimicking the living things. • The three central surface mechanisms were reviewed. • Preparation, performance, and mechanism are critically evaluated. • First review of wettability based cellulose membrane as major material. • The current and future importance of the research are discussed. It is challenging to purify oily wastewater, which affects water-energy-food production. One promising method is membrane-based separation. This paper reviews the current research trend of applying cellulose as a membrane material that mimics one of three typical biostructures: superhydrophobic, underwater superoleophobic, and Janus surfaces. Nature has provided efficient and effective structures through the evolutionary process. This has inspired many researchers to create technologies that mimic nature’s structures or the fabrication process. Lotus leaves, fish scales, and Namib beetles are three representative structures with distinct functional and surface properties: superhydrophobic, underwater superoleophobic, and Janus surfaces. The characteristics of these structures have been widely studied and applied to membrane materials to improve their performance. One attractive membrane material is cellulose, which has been studied from the perspective of its biodegradability and sustainability. In this review, the principles, mechanisms, fabrication processes, and membrane performances are summarized and compared. The theory of wettability is also described to build a comprehensive understanding of the concept. Finally, future outlook is discussed to challenge the gap between laboratory and industrial applications.     

Bacteriophages in water pollution control: Advantages and limitations

•Phages can be better indicators of enteric viruses than fecal indicator bacteria. •Multiple phages should be added to the microbial source tracking toolbox. •Engineered phage or phage cocktail can effectively target resistant bacteria. •In phage use, phage-mediated horizontal gene transfer cannot be ignored. •More schemes are needed to prevent phage concentration from decreasing. Wastewater is a breeding ground for many pathogens, which may pose a threat to human health through various water transmission pathways. Therefore, a simple and effective method is urgently required to monitor and treat wastewater. As bacterial viruses, bacteriophages (phages) are the most widely distributed and abundant organisms in the biosphere. Owing to their capacity to specifically infect bacterial hosts, they have recently been used as novel tools in water pollution control. The purpose of this review is to summarize and evaluate the roles of phages in monitoring pathogens, tracking pollution sources, treating pathogenic bacteria, infecting bloom-forming cyanobacteria, and controlling bulking sludge and biofilm pollution in wastewater treatment systems. We also discuss the limitations of phage usage in water pollution control, including phage-mediated horizontal gene transfer, the evolution of bacterial resistance, and phage concentration decrease. This review provides an integrated outlook on the use of phages in water pollution control.     

Copper fractal growth during recycling from waste printed circuit boards by slurry electrolysis

• Copper fractal growth was observed during WPCBs recycling by slurry electrolysis. • Dendrites fractal growth could be controlled by additive during electrodeposition. • Additive was proved to be an effective way to refine the copper crystal. • These findings contribute to enrich the study of slurry electrolysis. Superfine copper particles could be directly prepared from waste printed circuit boards by slurry electrolysis. Meanwhile, copper fractal growth could be observed. To better understand this phenomenon, the factors that affect copper dendrites in a point-cathode system were discussed in detail. These results showed that the fractal degree of copper dendrites increased as the increase of applied voltage and the decrease of copper sulfate and gelatin concentrations. Sodium lauryl sulfate and hydrochloric acid concentrations could not significantly impact the fractal degree of copper dendrites, while gelatin concentration could. The minimum copper fractal dimension was 1.069 when gelatin and copper sulfate concentration was 120 mg/L and 0.1 mol/L, respectively with an applied voltage of 11 V. Moreover, the results diffusion-limited aggregation model demonstrated that particle translational speed, particle numbers and binding probability significantly affected copper dendrite patterns. The scanning electron microscopy results indicated that the three additives greatly affected the refinement of the copper crystal. These findings contribute to enrich the theoretical study on metals recovery from e-waste by slurry electrolysis.     

Sorption mechanisms of diphenylarsinic acid on natural magnetite and siderite: Evidence from sorption kinetics,sequential extraction and extended X-ray absorption fine-structure spectroscopy analysis

• DPAA sorption followed pseudo-secondary and intra-particle diffusion models. • Chemical bonding and intra-particle diffusion were dominant rate-limiting steps. • DPAA simultaneously formed inner- and outer-sphere complexes on siderite. • DPAA predominantly formed occluded inner-sphere complexes on magnetite. • Bidentate binuclear bond was identified for DPAA on siderite and magnetite. Diphenylarsinic acid (DPAA) is both the prime starting material and major metabolite of chemical weapons (CWs). Because of its toxicity and the widespread distribution of abandoned CWs in burial site, DPAA sorption by natural Fe minerals is of considerable interest. Here we report the first study on DPAA sorption by natural magnetite and siderite using macroscopic sorption kinetics, sequential extraction procedure (SEP) and microscopic extended X-ray absorption fine-structure spectroscopy (EXAFS). Our results show that the sorption pseudo-equilibrated in 60 minutes and that close to 50% and 20%–30% removal can be achieved for magnetite and siderite, respectively, at the initial DPAA concentrations of 4–100 mg/L. DPAA sorption followed pseudo-secondary and intra-particle diffusion kinetics models, and the whole process was mainly governed by intra-particle diffusion and chemical bonding. SEP and EXAFS results revealed that DPAA mainly formed inner-sphere complexes on magnetite (>80%), while on siderite it simultaneously resulted in outer-sphere and inner-sphere complexes. EXAFS analysis further confirmed the formation of inner-sphere bidentate binuclear corner-sharing complexes (²C) for DPAA. Comparison of these results with previous studies suggests that phenyl groups are likely to impact the sorption capacity and structure of DPAA by increasing steric hindrance or affecting the way the central arsenic (As) atom maintains charge balance. These results improve our knowledge of DPAA interactions with Fe minerals, which will help to develop remediation technology and predict the fate of DPAA in soil-water environments.     

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ electrochemical impedance spectroscopy

• RED performance and stack resistance were studied by EIS and LSV. • Interface resistance were discriminated from Ohmic resistance by EIS. • Impacts of spacer shadow effect and concentration polarization were analyzed. • Ionic short current reduced the power density for more cell pairs. • The results enabled to predict RED performance with different configurations. Reverse electrodialysis (RED) is an emerging membrane-based technology for the production of renewable energy from mixing waters with different salinities. Herein, the impact of the stack configuration on the Ohmic and non-Ohmic resistances as well as the performance of RED were systematically studied by using in situ electrochemical impedance spectroscopy (EIS). Three different parameters (membrane type, number of cell pairs and spacer design) were controlled. The Ohmic and non-Ohmic resistances were evaluated for RED stacks equipped with two types of commercial membranes (Type I and Type II) supplied by Fujifilm Manufacturing Europe B.V: Type I Fuji membranes displayed higher Ohmic and non-Ohmic resistances than Type II membranes, which was mainly attributed to the difference in fixed charge density. The output power of the stack was observed to decrease with the increasing number of cell pairs mainly due to the increase in ionic shortcut currents. With the reduction in spacer thickness from 750 to 200 µm, the permselectivity of membranes in the stack decreased from 0.86 to 0.79 whereas the energy efficiency losses increased from 31% to 49%. Overall, the output of the present study provides a basis for understanding the impact of stack design on internal losses during the scaling-up of RED.     

Submerged arc plasma system combined with ozone oxidation for the treatment of wastewater containing non-degradable organic compounds

• Submerged arc plasma was introduced in terms of wastewater treatment. • Ozone oxidation was coupled with submerged arc plasma system. • Ozone was converted into O and O₂ by submerged arc plasma. • Decomposition rate was accelerated by submerged arc plasma. • Introduction of ozone led to significant increase in mineralization. Submerged arc plasma technology was assessed for the removal of phenols from wastewater. The OH radicals generated from the boundary between the plasma and waste solution were considered as a significant factor on the degradation reaction. In this study, the effects of highly energetic electrons released from the submerged arc plasma were mainly studied. The highly energetic electrons directly broke the strong chemical bond and locally increased the reaction temperatures in solution. The effects of the submerged-arc plasma on the decomposition of phenol are discussed in terms of the input energy and initial concentration. The single use of submerged arc plasma easily decomposed the phenol but did not increase the mineralization efficiency. Therefore, the submerged arc plasma, coupled with the ozone injection, was investigated. The submerged arc plasma combined with ozone injection had a synergic effect, which led to significant improvements in mineralization with only a small increase in input energy. The decomposition mechanism of phenol by the submerged arc plasma with the ozone was analyzed.     

Stress-related ecophysiology of members of the genus Rhodanobacter isolated from a mixed waste contaminated subsurface

• Rhodanobacter spp. are dominant in acidic, high nitrate and metal contaminated sites. • Dominance of Rhodanobacter is likely due to tolerance to low pH and heavy metals. • High organic content increases stress tolerance capacity. • Longer incubation time is critical for accurate assessment of MIC (various stresses). This work examines the physiologic basis of stress tolerance in bacterial strains of the genus Rhodanobacter that dominate in the acidic and highly metal contaminated near-source subsurface zone of the Oak Ridge Integrated Field Research Challenge (ORIFRC) site. Tolerance of R. denitrificans to levels of different stresses were studied in synthetic groundwater medium and R2A broth. Two strains of R. denitrificans, strains 2APBS1^T and 116-2, tolerate low to circumneutral pH (4–8), high Uranium (1 mmol/L), elevated levels of nitrate (400 mmol/L) and high NaCl (2.5%). A combination of physiologic traits, such as growth at low pH, increased growth in the presence of high organics concentration, and tolerance of high concentrations of nitrate, NaCl and heavy metals is likely responsible for dominance of Rhodanobacter at the ORIFRC site. Furthermore, extended incubation times and use of low carbon media, better approximating site groundwater conditions, are critical for accurate determination of stress responses. This study expands knowledge of the ecophysiology of bacteria from the genus Rhodanobacter and identifies methodological approaches necessary for acquiring accurate tolerance data.     

Electricity-driven ammonia oxidation and acetate production in microbial electrosynthesis systems

• MES was constructed for simultaneous ammonia removal and acetate production. • Energy consumption was different for total nitrogen and ammonia nitrogen removal. • Energy consumption for acetate production was about 0.04 kWh/g. • Nitrate accumulation explained the difference of energy consumption. • Transport of ammonia and acetate across the membrane deteriorated the performance. Microbial electrosynthesis (MES) is an emerging technology for producing chemicals, and coupling MES to anodic waste oxidation can simultaneously increase the competitiveness and allow additional functions to be explored. In this study, MES was used for the simultaneous removal of ammonia from synthetic urine and production of acetate from CO₂. Using graphite anode, 83.2%±5.3% ammonia removal and 28.4%±9.9% total nitrogen removal was achieved, with an energy consumption of 1.32 kWh/g N for total nitrogen removal, 0.45 kWh/g N for ammonia nitrogen removal, and 0.044 kWh/g for acetate production. Using boron-doped diamond (BDD) anode, 70.9%±12.1% ammonia removal and 51.5%±11.8% total nitrogen removal was obtained, with an energy consumption of 0.84 kWh/g N for total nitrogen removal, 0.61 kWh/g N for ammonia nitrogen removal, and 0.043 kWh/g for acetate production. A difference in nitrate accumulation explained the difference of total nitrogen removal efficiencies. Transport of ammonia and acetate across the membrane deteriorated the performance of MES. These results are important for the development of novel electricity-driven technologies for chemical production and pollution removal.     

Temporal variation of PM2.5-associated health effects in Shijiazhuang,Hebei

•Annual mean PM_2.5 in Shijiazhuang were 87, 95, and 82 µg/m³ in 2015–2017. •Health risk of cardiovascular system was higher than respiratory system. •Premature mortality attributed to PM_2.5 was 5088 people in 2017. •ΔMort and YLL reduced by 84.2% and 84.6% when PM_2.5 reduced to 10 µg/m³. •Health risks due to PM_2.5 were severe in Shijiazhuang in 2015–2017. Shijiazhuang is one of the cities in the North China Plain. In recent decades, this city has experienced high levels of fine particulate matter (PM_2.5), which have potentially significant effects on human health. In this study, the health effects of PM_2.5 exposure in Shijiazhuang were estimated by applying an integrated exposure-response model. Premature mortality, years of life lost (YLL), and the mortality benefits linked to reduced levels of PM_2.5 were quantified for the period 2015–2017. In 2015, 2016, and 2017, cerebrovascular diseases caused the highest premature mortality (2432, 2449, and 2483, respectively), followed by ischemic heart diseases (1391, 1479, and 1493, respectively), lung cancer (639,660, and 639, respectively), and chronic obstructive pulmonary diseases (533, 519, and 473, respectively). Notably, the total number of premature deaths caused by PM_2.5 exposure in Shijiazhuang in 2015, 2016, and 2017 were 4994, 5107, and 5088, respectively. Moreover, the YLL in the same years were 47001, 47880 and 47381, respectively. Interestingly, the YLL per 1000 females was lower than that per 1000 males. Finally, we noted that premature mortality and YLL decreased by 84.2% and 84.6% when the PM_2.5 levels diminished to 10 µg/m³. Overall, the results of this study improve our understanding of how high PM_2.5 concentrations affect human health and suggest the application of more stringent measures in Shijiazhuang to alleviate the associated health risks.     

Hexavalent chromium in drinking water: Chemistry,challenges and future outlook on Sn(II)- and photocatalyst-based treatment

• Wide occurrence of Cr(VI) in US source drinking water. • A strong dependence of occurrence on groundwater sources. • Elucidate Redox and equilibrium chemistry of Cr(VI). • Sn(II)-based and TiO₂-based reductive treatments hold extreme promise. • Key challenges include residual waste, Cr(VI) re-generation and socioeconomic drivers. Chromium (Cr) typically exists in either trivalent and hexavalent oxidation states in drinking water, i.e., Cr(III) and Cr(VI), with Cr(VI) of particular concern in recent years due to its high toxicity and new regulatory standards. This Account presented a critical analysis of the sources and occurrence of Cr(VI) in drinking water in the United States, analyzed the equilibrium chemistry of Cr(VI) species, summarized important redox reaction relevant to the fate of Cr(VI) in drinking water, and critically reviewed emerging Cr(VI) treatment technologies. There is a wide occurrence of Cr(VI) in US source drinking water, with a strong dependence on groundwater sources, mainly due to naturally weathering of chromium-containing aquifers. Challenges regarding traditional Cr(VI) treatment include chemical cost, generation of secondary waste and inadvertent re-generation of Cr(VI) after treatment. To overcome these challenges, reductive Cr(VI) treatment technologies based on the application of stannous tin or electron-releasing titanium dioxide photocatalyst hold extreme promise in the future. To moving forward in the right direction, three key questions need further exploration for the technology implementation, including effective management of residual waste, minimizing the risks of Cr(VI) re-occurrence downstream of drinking water treatment plant, and promote the socioeconomic drivers for Cr(VI) control in the future.     

Significant increase of assimilable organic carbon (AOC) levels in MBR effluents followed by coagulation,ozonation and combined treatments: Implications for biostability control of reclaimed water

• Annual AOCs in MBR effluents were stable with small increase in warmer seasons. • Significant increase in AOC levels of tertiary effluents were observed. • Coagulation in prior to ozonation can reduce AOC formation in tertiary treatment. • ∆UV₂₅₄ and SUVA can be surrogates to predict the AOC changes during ozonation. As water reuse development has increased, biological stability issues associated with reclaimed water have gained attention. This study evaluated assimilable organic carbon (AOC) in effluents from a full-scale membrane biological reactor (MBR) plant and found that they were generally stable over one year (125–216 µg/L), with slight increases in warmer seasons. After additional tertiary treatments, the largest increases in absolute and specific AOCs were detected during ozonation, followed by coagulation-ozonation and coagulation. Moreover, UV₂₅₄ absorbance is known to be an effective surrogate to predict the AOC changes during ozonation. Applying coagulation prior to ozonation of MBR effluents for removal of large molecules was found to reduce the AOC formation compared with ozonation treatment alone. Finally, the results revealed that attention should be paid to seasonal variations in influent and organic fraction changes during treatment to enable sustainable water reuse.     

Less attention paid to waterborne SARS-CoV-2 spreading in Beijing urban communities

• A survey on individual’s perception of SARS-CoV-2 transmission was conducted. • Waterborne transmission risks are far less perceived by individuals. • Precautions of preventing wastewater mediated transmission are implemented. • The precautions for wastewater transmission are less favored by the public. • Education level differs the most regarding to waterborne transmission perception. SARS-CoV-2 has been detected in various environmental media. Community and individual-engaged precautions are recommended to stop or slow environmentally-mediated transmission. To better understand the individual’s awareness of and precaution to environmental dissemination of SARS-CoV-2, an online survey was conducted in Beijing during March 14–25, 2020. It is found that the waterborne (especially wastewater mediated) spreading routes are far less perceived by urban communities. The precautions for wastewater transmission are less favored by the public than airborne and solid waste mediated spreading routes. Such risk communication asymmetry in waterborne transmission will be further enlarged in places with fragile water system. Furthermore, education level is the most significant attribution (Sig.<0.05) that causes the difference of awareness and precautions of the waterborne transmission among the respondents, according to the variance analysis results. Our survey results emphasize the urgent need for evidence-based, multifactorial precautions for current and future outbreaks of COVID-19.