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The disposal of electroplating sludge (ES) is a major challenge for the sustainable development of the electroplating industry. ESs have a significant environmental impact, occupying valuable land resources and incurring high treatment costs, which increases operational expenses for companies. Additionally, the high concentration of hazardous substances in ES poses a serious threat to both the environment and human health. Despite extensive scholarly research on the harmless treatment and resource utilization of ES, current technology and processes are still unable to fully harness its potential. This results in inefficient resource utilization and potential environmental hazards. This article analyzes the physicochemical properties of ES, discusses its ecological hazards, summarizes research progress in its treatment, and elaborates on methods such as solidification/stabilization, heat treatment, wet metallurgy, pyrometallurgy, biotechnology, and material utilization. It provides a comparative summary of different treatment processes while also discussing the challenges and future development directions for technologies aimed at effectively utilizing ES resources. The objective of this text is to provide useful information on how to address the issue of ES treatment and promote sustainable development in the electroplating industry.

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An efficient cathode for a Fenton-like reaction based on hydrogen peroxide (H2O2) has significant implications for the potential application of the advanced oxidation process. However, the low H2O2 selectivity and efficient activation remain challenging in wastewater treatment. In the present study, a single Fe atom doped, nitrogen-coordinated molybdenum disulfide (Fe1/N/MoS2) cathode that exhibited asymmetric wettability and self-absorption molecular oxygen was successfully prepared for pollutant degradation. The X-ray absorption near-edge structure and extended X-ray absorption fine structure of Fe1N3 in the Fe1/N/MoS2 catalyst were determined. The electronic structure demonstrated favorable H2O2 selectivity (75%) in a neutral solution and the cumulative hydroxyl radical concentration was 14 times higher than the pure carbon felt. After 10 consecutive reaction experiments, the removal ratio of paracetamol still reached 97%, and the catalytic performance did not decrease significantly. This work deeply understands the catalytic mechanism of Fenton-like reaction between single Fe atom and MoS2 double reaction sites, and proves that the regulation of the electronic structure of Fe single atom is an effective strategy to improve the activity of Fenton-like reaction.

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The remediation of contaminated soils is a great challenge for global environmental sciences and engineering. The landfill was a kind of infrastructure to deal with waste from different sources while it would also cause the threat to groundwater. Cut-off walls and pumping wells were usually applied in the landfill to prevent the spread of pollutants to wider areas. However, the combination of using both of methods was rarely analyzed, especially using field data for calibrating and fitting groundwater flow and pollutant transport. 7 monitoring wells were arranged in the study area to survey the subsurface seepage. The pollution monitoring was carried out for a period of 50 days, covering 31 types of inorganic and organic pollutants. The concentration of 2,4,6-trichlorophenol (TCP) was 556.7 times greater than the standard concentration. A coupled numerical model of groundwater flow and pollutant transport was developed to assess the effectiveness of various control methods. Three options were tested, including the implementation of a single cut-off wall as well as a combination of a cut-off wall and a pumping well, for preventing the discharge of pollutants from landfills. The combination of a cut-off wall and a pumping well is the best strategy for removal of TCP. The combination approaches lead to a reduction of pollution plumes by a factor of 11 compared to the case without pollution control measures. The research findings may provide a basis and reference for the application of cutoff walls and pumping well in landfill sites or contaminated groundwater.

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Conventional fossil fuels are relied on heavily to meet the ever-increasing demand for energy required by human activities. However, their usage generates significant air pollutant emissions, such as NOx, SOx, and particulate matter. As a result, a complete air pollutant control system is necessary. However, the intensive operation of such systems is expected to cause deterioration and reduce their efficiency. Therefore, this study evaluates the current air pollutant control configuration of a coal-powered plant and proposes an upgraded system. Using a year-long dataset of air pollutants collected at 30-min intervals from the plant's telemonitoring system, untreated flue gas was reconstructed with a variational autoencoder. Subsequently, a superstructure model with various technology options for treating NOx, SOx, and particulate matter was developed. The most sustainable configuration, which included reburning, desulfurization with seawater, and dry electrostatic precipitator, was identified using an artificial intelligence (AI) model to meet economic, environmental, and reliability targets. Finally, the proposed system was evaluated using a Monte Carlo simulation to assess various scenarios with tightened discharge limits. The untreated flue gas was then evaluated using the most sustainable air pollutant control configuration, which demonstrated a total annual cost, environmental quality index, and reliability indices of 44.1 × 106 USD/year, 0.67, and 0.87, respectively.

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Under carbon peak and carbon neutrality constraints, the coal chemical industry should take stricter measures to tackle carbon reduction. Based on the intensity differences of five major coal and carbon reduction measures applied by the coal chemical industry, which include raw material structure adjustment, fuel structure adjustment, energy-saving technology transformation, terminal capture technology, and industrial structure adjustment, this study adopted the downstream sector demand method and project method, combined with the air pollution reduction model, to predict three scenarios (benchmark, policy, and enhancement) of coal chemical industry peak year and peak amount of coal consumption and carbon dioxide emission, associated with air pollutant reduction row effects. The results showed that coal consumption under the benchmark and policy scenarios of the coal chemical industry is expected to reach a peak in the late period of China's "14th Five-Year Plan", with peak values of 0.96 billion and 0.93 billion tons, respectively. By contrast, under the enhanced scenario, it is expected to peak in the early period of the "14th Five-Year Plan" with a value of 0.91 billion tons. The carbon peak will arrive in the late period of the "15th Five-Year Plan" under the benchmark scenario but in the early and late period of the "14th Five-Year Plan" under the policy and enhanced scenarios, with peak values of approximately 0.64 billion, 0.57 billion, and 0.55 billion tons, respectively. Controlling the construction scale of new coal chemical projects, tapping the space for raw material substitution, and speeding up the energy-saving technological transformation are important measures for coal and carbon control in the coal chemical industry. The implementation of coal and carbon reduction measures of the coal chemical industry will coordinately reduce air pollutant emissions, such as SO2, NOx, PM, and VOCs by 37, 43, 11, and 28 thousand tons per year after 2035.

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Industrial development is an essential foundation of the national economy, but the industry is also the largest source of air pollution, of which power plants, iron and steel, building materials, and other industries emit large amounts of pollutants. Therefore, the Chinese government has promulgated a series of stringent emission regulations, and it is against this backdrop that research into air pollution control technologies for key industrial sectors is in full swing. In particular, during the 13th Five-Year Plan, breakthroughs have been made in pollution control technology for key industrial sectors. A multi-pollutant treatment technology system of desulfurization, denitrification, and dust collection, which applies to key industries such as power plants, steel, and building materials, has been developed. High-performance materials for the treatment of different pollutants, such as denitrification catalysts and desulfurization absorbers, were developed. At the same time, multi-pollutant synergistic removal technologies for flue gas in various industries have also become a hot research topic, with important breakthroughs in the synergistic removal of NOx, SOx, and Hg. Due to the increasingly stringent emission standards and regulations in China, there is still a need to work on the development of multi-pollutant synergistic technologies and further research and development of synergistic abatement technologies for CO2 to meet the requirements of ultra-low emissions in industrial sectors.

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Pollutant removal and resource recovery from high-humidity flue gas after desulfurization in a thermal power plant are crucial for improving air quality and saving energy. This study developed a flue gas treatment method involving phase transition enhanced by corona discharge based on laboratory research and established a field-scale unit for demonstration. The results indicate that an adequate increase in size will improve the ease of particle capture. A wet electrostatic precipitator is applied before the condensing heat exchangers to enhance the particle growth and capture processes. This results in an increase of 58% in the particle median diameter in the heat exchanger and an emission concentration below 1 mg/m3. Other pollutants, such as SO3 and Hg, can also be removed with emission concentrations of 0.13 mg/m3 and 1.10 µg/m3, respectively. Under the condensation enhancement of the method, it is possible to recover up to 3.26 t/h of water from 200 000 m3/h saturated flue gas (323 K), and the quality of the recovered water meets the standards stipulated in China. Additionally, charge-induced condensation is shown to improve heat recovery, resulting in the recovery of more than 43.34 kJ/h·m3 of heat from the flue gas. This method is expected to save 2628 t of standard coal and reduce carbon dioxide emission by 2% annually, contributing to environmental protection and global-warming mitigation.

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The emission of air pollutants from the municipal solid waste (MSW) incineration is one of the major concerns in air pollution. The up-to-date emission situation for Chinese MSW incineration is largely unknown. The emission factors (EFs) are the key parameters to estimate the emissions from MSW incineration. The localized EFs from MSW incineration in Shanghai, China were established using continuous emission monitoring system data from 2017 to 2019. Our results showed that the EFs were 9.80 g t-1 of PM, 46.62 g t-1 of SO2, 812.68 g t-1 of NOx, 25.84 g t-1 of CO, and 17.49 g t-1 of HCl for the period 2017-2019, nearly 1.7-24.2 times lower than those in 2010, implying that the current EFs should be updated to avoid overestimation of MSW emissions in China. Compared with 2010, the emissions of PM, SO2, CO, and HCl in 2019 were significantly reduced by 84%, 69%, 47%, and 72%, respectively, except for NOx with a 106% increase, although the corresponding MSW incineration amount increased by 356%. The current levels of air pollutants from MSW incineration have already met the current national emission standard as well as the stricter standard of the European Union (98.87%-99.91%). Our findings suggest that China should update the current standards of MSW incineration, which can be a benefit for the prevention and control of MSW incineration in the future. It is still challenging to control NOx emissions from MSW incineration for Shanghai and even greater China.

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The concentration of condensable particulate matter (CPM) has gradually exceeded that of filterable particulate matter emitted from industrial plants equipped with advanced air pollution control systems. However, there is still no available online technology to measure CPM emissions. Based on the significant linear correlations (R2 > 0.87, p < 3 × 10-3) between the electrical conductivity (EC) values and ionic mass concentrations of the CPM solutions when the interference of H+ was excluded. We developed an online inorganic CPM monitoring system, including a cooling and condensation unit, pH and EC meters, a self-cleaning unit, and an automatic control unit. The CPM mass concentrations obtained by the developed online monitoring system agree well (mean bias 3.8-20.7%) with those obtained by the offline system according to USEPA Method 202 when used in parallel during real-world studies. Furthermore, individual ion mass concentrations of CPMs can even be retrieved separately with a time resolution of one hour when industrial plants are under steady operating conditions. The newly developed system makes the online monitoring of CPM emissions available and lays a foundation for the control of CPM emitted from industrial sources to further improve air quality.

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Although Fenton or Fenton-like reactions have been widely used in the environment, biology, life science, and other fields, the sharp decrease in their activity under macroneutral conditions is still a large problem. This study reports a MoS2 cocatalytic heterogeneous Fenton (CoFe2 O4 /MoS2 ) system capable of sustainably degrading organic pollutants, such as phenol, in a macroneutral buffer solution. An acidic microenvironment in the slipping plane of CoFe2 O4 is successfully constructed by chemically bonding with MoS2 . This microenvironment is not affected by the surrounding pH, which ensures the stable circulation of Fe3+ /Fe2+ on the surface of CoFe2 O4 /MoS2 under neutral or even alkaline conditions. Additionally, CoFe2 O4 /MoS2 always exposes "fresh" active sites for the decomposition of H2 O2 and the generation of 1 O2 , effectively inhibiting the production of iron sludge and enhancing the remediation of organic pollutants, even in actual wastewater. This work not only experimentally verifies the existence of an acidic microenvironment on the surface of heterogeneous catalysts for the first time, but also eliminates the pH limitation of the Fenton reaction for pollutant remediation, thereby expanding the applicability of Fenton technology.

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Particle air filters used in central residential forced-air systems are most commonly evaluated for their size-resolved removal efficiency for particles 0.3-10 µm using laboratory tests. Little information exists on the removal efficiency of commercially available residential filters for particles smaller than 0.3 µm or for integral measures of mass-based aerosol concentrations (eg, PM2.5 ) or total number concentrations (eg, ultrafine particles, or UFPs) that are commonly used in regulatory monitoring and building measurements. Here, we measure the size-resolved removal efficiency of 50 new commercially available residential HVAC filters installed in a recirculating central air-handling unit in an unoccupied apartment unit using alternating upstream/downstream measurements with incense and NaCl as particle sources. Size-resolved removal efficiencies are then used to estimate integral measures of PM2.5 and total UFP removal efficiency for the filters assuming they are challenged by 201 residential indoor particle size distributions (PSDs) gathered from the literature. Total UFP and PM2.5 removal efficiencies generally increased with manufacturer-reported filter ratings and with filter thickness, albeit with numerous exceptions. PM2.5 removal efficiencies were more influenced by the assumption for indoor PSD than total UFP removal efficiencies. Filters with the same ratings but from different manufacturers often had different removal efficiencies for PM2.5 and total UFPs.

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A series of CuO-MnOx modified catalysts were prepared, and proposed for simultaneous removal of Hg° and NO from flue gas. As Mn loading value was 5%, the high value of 90% Hg and 60% NOx were removed efficiently. With gradual increasing of reaction temperature, the mercury removal efficiency (Mercury RE) first increased to 92% then decreased slightly, while NOx removal efficiency (NOx RE) exhibited a trend of continuous increase. O2 had promotional effect on the double pollutants removal, while NH3 had slightly negative effect on Hg° removal. As 5% O2 was added into system, the removal efficiency of Hg and NOx rose by 30% and 47%, respectively. Unfortunately, Mercury RE decreased to 90% in the presence of 500 ppm NH3. Overall, superior Mercury RE (>90%) and NOx RE (78%) were performed over 8%CuO-5%MnOx/AC-H at 200 °C. XRD results revealed calcination affected catalysts activity by playing a role in active components formation at different temperature. In XPS spectra, new formation of HgO and Hg° adsorption on spent catalysts revealed the possible reaction processes that the conversion of CuO and MnO2 on fresh catalyst to other species benefited HgO formation. The removal mechanism might be a combination of Langmuir-Hinshelwood and Mars-van-Krevelen mechanism.

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In consideration of severe eutrophication of scenic water caused by pollutants released from sediments in summer, calcium peroxide (CaO2) was adopted as the slow release peroxide to improve the water quality in a field experiment of 600 m2. The effect of CaO2 on the overlying water, interstitial water, sediment, and sediment microorganisms of scenic water was studied. Results for two months indicated that the dissolved oxygen (DO) concentration of the overlying water in the test zone was 3.78 times that in the control zone; the oxidation-reduction potential (ORP) in the overlying water and sediment increased significantly (p = 0.002 and p = 0). Meanwhile, CaO2 could effectively inhibit the release of nitrogen (N) and phosphorus (P) from the sediment and could obviously reduce the concentrations of N and P in the overlying water by enhancing the microbiological action. Moreover, the average concentrations of total nitrogen and total phosphorus in the overlying water of the test zone were 46.27% and 50.51% of those in control zone, respectively, and the concentrations of N and P in the interstitial water decreased during the entire experiment. In addition, CaO2 decreased the relative abundance of anaerobic bacteria in the sediment, whereas it increased that of aerobic bacteria and promoted the appearance of the functional bacteria, such as Nitrospirae and Thermodesulfoba. In conclusion, CaO2 can improve the DO and ORP in the eutrophic water effectively and change the microbial community in the sediment to a certain extent, thereby controlling the pollutants released from the sediment and reducing the N and P concentrations in the overlying water. Thus, CaO2 can effectively realize the purification and restoration of the severely eutrophic scenic water.

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The survival of aquatic biota in stream ecosystems depends on both water quantity and quality, and is particularly susceptible to degraded water quality in regulated rivers. Maintenance of environmental flows (e-flows) for aquatic biota with optimum water quantity and quality is essential for sustainable ecosystem services, especially in developing regions with insufficient stream monitoring of hydrology, water quality and aquatic biota. Few e-flow methods are available that closely link aquatic biota tolerances to pollutant concentrations in a simple and practical manner. In this paper a new method was proposed to assess e-flows that aimed to satisfy the requirements of aquatic biota for both the quantity and quality of the streamflow by linking fish tolerances to water quality criteria, or the allowable concentration of pollutants. For better operation of water projects and control of pollutants discharged into streams, this paper presented two coefficients for streamflow adjustment and pollutant control. Assessment of e-flows in the Wei River, the largest tributary of the Yellow River, shows that streamflow in dry seasons failed to meet e-flow requirements. Pollutant influx exerted a large pressure on the aquatic ecosystem, with pollutant concentrations much higher than that of the fish tolerance thresholds. We found that both flow velocity and water temperature exerted great influences on the pollutant degradation rate. Flow velocity had a much greater influence on pollutant degradation than did the standard deviation of flow velocity. This study provides new methods to closely link the tolerance of aquatic biota to water quality criteria for e-flow assessment. The recommended coefficients for streamflow adjustment and pollutant control, to dynamically regulate streamflow and control pollutant discharge, are helpful for river management and ecosystems rehabilitation. The relatively low data requirement also makes the method easy to use efficiently in developing regions, and thus this study has significant implications for managing flows in polluted and regulated rivers worldwide.

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Coal burning in power plants and industrial boilers is the largest combustion source of mercury emissions in China. Together, power plants and industrial boilers emit around 250 tonnes of mercury each year, or around half of atmospheric mercury emissions from anthropogenic sources in the country. Power plants in China are generally equipped with multi-pollutant control technologies, which offer the co-benefit of mercury removal, while mercury-specific control technologies have been installed in some facilities. In contrast, most industrial boilers have only basic or no flue gas cleaning. A combination of measures, including energy conservation, coal switching and blending, reducing the mercury contents of coals through washing, combustion controls, and flue gas cleaning, can be used to reduce mercury emissions from these stationary combustion sources. More stringent emission standards for the major air pollutants from coal-fired power plants and industrial boiler, along with standards for the previously unregulated mercury, were implemented recently, which is expected to bring significant reduction in their mercury emissions through the necessary upgrades of multi-pollutant and mercury-specific control technologies. Meanwhile, strong monitoring capacity and strict enforcement are necessary to ensure that the combustion sources operate in compliance with the new emission standards and achieve significant reduction in the emissions of mercury and other air pollutants.

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Industrial activities result in unintentional production of multiple types of persistent organic pollutants (POPs) at various concentrations. Because of the potential adverse effect of these POPs on the environment, biota and human health, methods for controlling emission of POPs are required. Development and application of techniques for controlling emissions of POPs can be a technical and economic burden for the industry involved. Therefore, from the point of view of cost-benefit analysis, reducing emissions of multiple pollutants at the same time is optimal for sustainable industrial development. Although techniques have been developed for reducing the emissions of individual POPs, such as dioxins, further work is required on multi-POP control emissions from industrial activities. This paper discusses three important aspects that need to be taken to achieve multi-POP control. These aspects include the establishment of a comprehensive system for evaluating the risk from emissions of multiple POPs, determination of indicators for total emissions of multiple POPs, and the preparation and application of functional materials to inhibit formation of multiple POPs. These discussion might be helpful for the future research on the multi-POP control in industry.

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Our work reported the CO2-assisted mitigation of PAHs and VOCs in the thermo-chemical process (i.e., pyrolysis). To investigate the pyrolysis of used tires to recover energy and chemical products, the experiments were conducted using a laboratory-scale batch-type reactor. In particular, to examine the influence of the CO2 in pyrolysis of a tire, the pyrolytic products including C1-5-hydrocarbons (HCs), volatile organic carbons (VOCs), and polycyclic aromatic hydrocarbons (PAHs) were evaluated qualitatively by gas chromatography (GC) with mass spectroscopy (MS) as well as with a thermal conductivity detector (TCD). The mass balance of the pyrolytic products under various pyrolytic conditions was established on the basis of their weight fractions of the pyrolytic products. Our experimental work experimentally validated that the amount of gaseous pyrolytic products increased when using CO2 as a pyrolysis medium, while substantially altering the production of pyrolytic oil in absolute content (7.3-17.2%) and in relative composition (including PAHs and VOCs). Thus, the co-feeding of CO2 in the pyrolysis process can be considered an environmentally benign and energy efficient process.

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The Community Multi-scale Air Quality modeling system is used to investigate the response of atmospheric visibility to the emission reduction from different sectors (i.e. industries, traffic and power plants) in the Yangtze River Delta, China. Visibility improvement from exclusive reduction of NOx or VOC emission was most inefficient. Sulfate and organic aerosol would rebound if NOx emission was exclusively reduced from any emission sector. The most efficient way to improve the atmospheric visibility was proven to be the multi-pollutant control strategies. Simultaneous emission reductions (20-50%) on NOx, VOC and PM from the industrial and mobile sectors could result in 0.3-1.0 km visibility improvement. And the emission controls on both NOx (85%) and SO2 (90%) from power plants gained the largest visibility improvement of up to 4.0 km among all the scenarios. The seasonal visibility improvement subject to emission controls was higher in summer while lower in the other seasons.

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