In order to summarize the effectiveness and systematically analyze the problems during the comprehensive treatment of Dianchi Lake water environment, the literature research and other methods were used to analyze the water quality evolution process and governance measures of Dianchi Lake. The treatment of Dianchi Lake was divided into four stages: 1) Exploring period (1988-1995), preliminary methods for Dianchi governance against the significant decrease of water quality were explored. 2) Engineering period (1996-2006), the point source pollution control was adopted as the leading governance model in response to the increase in sewage discharge and water intake for industry and agriculture. 3) Systemic treatment period (2007-2015), in 2007, Dianchi Lake was listed as the Major Science and Technology Program for Water Pollution Control and Treatment (Water Projects for short). The central and local governments proposed a comprehensive pollution control idea, with the “six major projects” as the main line, supported by Water Projects, and the basin water pollution systematic treatment was promoted. 4) Precise treatment period (since 2016), a new idea of “scientific, systematic, intensive, lawful” was formed. By strengthening refined management, promoting the tackling of key scientific and technological problems and the application of R&D achievements, the water quality of Dianchi Lake had been improved significantly. However, the water ecological environment of Dianchi Lake was still grim, due to the serious problems such as the shortage of water resources, the heavy load of non-point source pollution in the basin, and the damage to the water ecology. The governance of Dianchi Lake during the 14th Five-Year Plan period should follow the idea of basin water quality target management, comprehensively promote the governance and management of water resources, water environment and water ecology, accelerate the water environmental infrastructure construction, strengthen the basin water replacement, and restore and maintain the functions of the lake ecosystem.

Integrated watershed management is very important for maintaining the health of watershed ecosystems and achieving sustainable development of watersheds. Modern watershed management should be guided by Xi Jinping's Ecological Civilization Thought. The connotation of integrated watershed management from the perspective of ecological civilization was explained, that is integrated watershed management should consider the overall situation of the whole watershed, make overall plans for protection and development, adopt comprehensive means such as administrative, legal, economic, scientific and technological, propaganda and educational and other means, coordinate the relationship between society, economy, environment and production, life, ecological water use, so as to promote the comprehensive, coordinated and sustainable development of the economy, society and ecological environment in the watershed. The current situation of water environment management in Erhai Lake Basin was analyzed. From the perspective of ecological civilization, the water environment management in Erhai Lake Basin must coordinate the ecological elements of the mountains, rivers, forests, fields, lakes and grasses, and coordinate the upstream and downstream, water and land, as well as the relationships between relevant departments and industries. The comprehensive management level of Erhai Lake Basin should be improved by perfecting the mechanism and system, strictly enforcing the law and supervision, enhancing the monitoring ability, strengthening the support of science and technology, and consolidating the supervision foundation, so as to promote the practice of water ecological civilization in lake basin.

Three-dimensional excitation-emission matrix spectroscopy (EEMs) combined with parallel factor analysis (PARAFAC) were used to analyze the components, humification degree and sources of dissolved organic matter (DOM) of rural black and odorous water bodies in Pingdu City of Shandong Province. The results showed that the DOM of rural black and odorous water bodies in the city contained five categories and six fluorescence components, including tryptophan-like fluorescence components (C1 and C6), humus-like fluorescence components (C2), fluorescence components produced by plankton activities (C3), humic acid-like fluorescence components (C4), and fulic-like fluorescence components (C5). The water bodies with fluorescence index, autochthonous index, humification index and freshness index of 1.6-1.9, 0.8-1.0, 0.6-3.0 and 0.80-0.95, respectively, accounted for 90% of all, indicating that the DOM in rural black and odorous water bodies in the city had the dual characteristics of endogenous and exogenous, and had weak humification characteristics. The correlation analysis showed that the positive correlation was found between C1, C2, C3 and C4, and a significant positive correlation existed between C2 and C4 (R²=0.98, P<0.01), and C5 and C6 had no correlation with other components, indicating that the sources of DOM components of rural black and smelly water bodies in the city were diverse.

The application rate of nitrogen and phosphate fertilizers has increased significantly in China over the past few decades. However, the over-dozed nutrients also lead to the serious problem of eutrophication in inland and coastal waters. The control of nitrogen and phosphorus nutrients is generally considered to be an important part of reducing lake eutrophication and cyanobacteria blooms. Currently, the accurate identification of nutrient sources and the quantitative deconstruction of the spatial representation of excess nutrient concentration still require special attention. Based on the statistical data of pollutants in Shiyan City and the relevant monitoring reports of eco-environmental protection departments, the source composition and spatial load distribution of nitrogen and phosphorus nutrients were analyzed by the output coefficient method and land use pattern identification. The results showed that total nitrogen and total phosphorus of Shiyan City were mainly from non-point sources, accounting for 81.84% and 80.08%, respectively, and point sources accounted for less. The total nitrogen pollution load mainly came from farmland runoff, accounting for 45.72% of the total, followed by dry and wet deposition pollution sources, accounting for 11.43% of the total. The total phosphorus pollution load also mainly came from farmland runoff, accounting for 30.51% of the total, followed by soil erosion, accounting for 22.28% of the total. The highest load intensity of total nitrogen into the river was 22.71 t/km², and the highest load intensity of total phosphorus into the river was 5.22 t/km².

Taihu Lake Watershed is one of the areas with acid deposition in China, and acid deposition has a significant effect on the loss of base ions in the basin. The release characteristics of base ions from the representative carbonate rocks and their weathered products as well as the widely distributed sandy loam soil in the watershed under the action of simulated acid solutions with different pH were studied by laboratory simulation tests. The results indicated that: 1)The release of base ions in carbonate rocks was significantly negatively associated with pH and the particle size of acid solution (P<0.01). During the 10 days test period, the minimum release of Ca²⁺ was 0.26 g/kg, and the maximum release was 14.30 g/kg, which was one order of magnitude higher than K⁺, Na⁺ and Mg²⁺. 2)The sensitivity of base ions in the weathered products of carbonate rocks and sandy loam soil to simulated acid solution was in the order of Ca²⁺>Mg²⁺>K⁺. The amount of base ions released was not only related to the pH of simulated acid solution, but also depended on the characteristics of the medium, including its total amount of ions, parent material environment and amount of exchangeable cations. 3)The buffering capacity of different media for simulated acid solution in Taihu Lake Watershed was significant distinction, that was, carbonate rocks>the weathered products of dolomite>the weathered products of limestone>sandy loam soil. It was considered that a large number of carbonates would neutralize protons rapidly, which was the key factor for carbonate rocks and their weathered products to have strong buffering capacity.

The runoffs from irrigation and drainage ditches are the major sources of nitrogen and phosphorus of Erhai Lake. In the Autumn of 2020, two catchments in the western Erhai Lake Basin were selected to analyze the change characteristics of ditch water quality in catchment scale and sub catchment scale under the rain condition, as well as the impact of land use on ditch water quality. The results indicated that the water quality of the ditches presented obvious spatial variation. In Shuangying catchment, the chemical oxygen demand (COD) of the ditch runoff was relatively high in the southeast, which ranged from 5.68-20.49 mg/L, and that of total nitrogen (TN) of the ditches in the north was relatively high, which ranged from 1.04-1.44 mg/L. The total phosphorus (TP) concentration decreased from east to west, and ammonia nitrogen (NH₃-N) concentration was generally low in the catchment. In Wanyang catchment, the COD concentration of the ditch runoff was relatively high in the south, which ranged from 5.02-14.22 mg/L, and the TN concentration was generally low, and the TP and NH₃-N concentrations were generally high in the ditches around Erhai Lake and north of the central part. The redundancy analysis indicated that the farmland and village were the major source of TP and NH₃-N in the ditch runoff. The unutilized water storage in ponds and wetlands may cause the ditch water quality pollution in the Autumn. The grass and forest land area presented negative relationship with the ditch water quality, but due to the low proportion and spatial location, it had little effect on reducing the pollution load into the sea. To reduce the impact of irrigation and drainage ditch backwater and rural domestic sewage on Erhai Lake, measures should be taken to strengthen the recycling of irrigation water, and improve the sewage interception project around the lake.

Based on the air quality index (AQI) data and NECP/NCAR reanalysis data, combined with the distribution heterogeneity coefficient (C_V) within the year, the characteristics of air quality variation and its relationship with atmospheric circulation in Southern Sichuan Urban Agglomeration in 2020 were analyzed. The results showed as follows. 1) The AQI value of Southern Sichuan Urban Agglomeration decreased as a whole, the air quality in summer and autumn was better than that in spring and winter; C_V rose slightly, and the uneven distribution of air quality within the year increased. Among them, the difference of air quality distribution was the biggest in winter and the smallest in summer, and the regional difference was larger in the west of Southern Sichuan Urban Agglomeration than that in the east. 2) Due to the effect of primary pollutant PM_2.5, the spatial distribution of AQI was high in the middle and low around, and combined with the influence of PM₁₀, the spatial distribution of AQI had obvious seasonal differences. The spatial variation characteristics of spring and winter were similar, forming a high value area in the middle and a low value area in the north, high in the west and low in the east in summer and high in the southeast and low in the northwest in autumn. 3) When the urban agglomeration in Southern Sichuan Urban Agglomeration was in the upper trough in spring and winter, the accumulation of cold air was not conducive to the occurrence of convection, and the pollutant discharge was not smooth, resulting in the high AQI values in the two seasons. In summer and autumn, due to the existence of subtropical high and low trough in mid-high latitude, it was easy to generate convection and precipitation. In addition, the convergence situation of wind field was obvious, and the pollutants were not easy to accumulate, so the AQI was low.

In order to investigate the causes of heavy pollution in Tianjin during the epidemic period of COVID-19 in 2020, the environmental monitoring, routine meteorological observation and 255 m meteorological tower gradient observation, together with WRF-Chem model simulation were used to discuss the sources and boundary layer characteristics of heavy pollution process during February 9-13th, 2020 in Tianjin. The results showed that the deterioration of horizontal and vertical diffusion conditions, weak air pressure field and warm and humid atmosphere on the ground were the main weather characteristics of this heavy pollution case. The regional transportation rate of external sources in the process of heavy pollution was 54.6%. The stable stratification (E and F) accounted for 67.5%, and the relatively stable atmosphere decreased the atmospheric diffusion condition, which was an important meteorological condition for the occurrence of this pollution. The inversion rate of the pollution process reached 50.0%, and the correlations between the vertical temperature difference, inversion thickness, inversion intensity and PM_2.5 concentration were 0.99, 0.90 and 0.56, respectively. The existence of inversion layer was the main factor to maintain the pollution process.

Most rainwater drainage pipelines in China have sediment accumulation phonomenon, which often blocks the pipeline and reduces the drainage capacity, resulting in water logging. Meanwhile, the sediment accumulation is also one of the main sources of abruptly pollution in the receiving water. In view of the above problems, the effects of sediments accumulation thickness, sediment surface roughness and pipeline slope on the drainage capacity of rainwater pipeline were studied through laboratory experiment. The results showed that with the pipeline slope of 2‰, and when pipe diameter was 150 mm, the sediment accumulation thickness increased from 20% to 70%, and the reduction rate of drainage capacity increased from 14.93% to 59.56%. According to the hydraulic similarity criterion, when the diameter of pipeline was 2 000 mm, the sediment accumulation thickness increased from 20% to 70%, and the reduction rate of drainage capacity increased from 44.78% to 73.75%. Therefore, the reduction rate of drainage capacity increased with the increase of sediment cumulative thickness and pipe diameter. The changing of surface roughness of the sediment has no markedly effect on the drainage capacity, under experimental conditions, the average increase in drainage capacity reduction was 5.93 percentage points, while the slope change had a more obvious effect on the drainage capacity. When the slope increased, the reduction range of drainage capacity was 12.30-28.83 percentage points. Overall, the research results could provide a support for the optimization design, maintenance management, monitoring and evaluation of urban rainwater drainage pipeline.

In order to compare the pollutant removal effects of different rainwater projects, the rainwater pollutant removal efficiencies of five measurements, including bioretention, grass swale, permeable concrete pavement, permeable brick pavement and vegetation brick pavement, were monitored. The results showed that the bioretention had high removal efficiencies on COD, SS, NH₃-N and TP, and the effluent water quality reached Class Ⅲ standard of Environmental Quality Standards for Surface Water (GB 3838-2002). Especially for COD and SS, the average removal rates reached 82.1% and 70.7%, respectively. Grass swale had a good removal effect on NH₃-N, with an average removal rate of 91.3%. However, TP concentration of effluent was higher than that of influent. The permeable brick pavement released NH₃-N, causing an increase of its concentration in the effluent. Comparing the three types of permeable pavements, the pollutant removal ability of the permeable concrete was the best comprehensively, and its average removal rates of COD, NH₃-N, TP and SS were 57.0%, 72.7%, 79.4%, and 82.2%, respectively. According to the monitoring results and literature reports comprehensively, it was found that bioretention and permeable concrete pavement had higher pollutant removal effects, and grass swale had outstanding performance in removing NH₃-N from rainwater. In the practical application of rainwater projects, appropriate measurement should be selected according to control objectives, costs and pollutant removal efficiency.

The treatment of flushing wastewater from scattered piggeries by anaerobic baffled reactor (ABR) was explored. The variations and differences of the microbial communities in the ABRs respectively with the influent mode-sequencing batch and the continuous operation under different pollution loads （3 operational phases) were compared. The results showed that, according to PCoA and cluster analysis, the microbial communities between the sequencing batch and continuous ABRs were similar under the same pollution load. The influence of the influent mode on microbial community structure was mainly presented in the first compartment (also the main removal area of COD). The five dominant genera in the continuous operation ABR were Clostridium_sensu_stricto_1, Norank_f_Anaerolineaceae, Christensenellaceae_R-7_group, Norank_c_Bacteroidetes_vadinHA17 and Norank_p_Candidate_division_WS6, with the relative abundance of 9.04%, 8.14%, 7.08%, 5.97% and 4.88%, respectively. While the five dominant genera in the sequencing batch ABR were Norank_c_Bacteroidetes_vadinHA17, Clostridium_sensu_stricto_1, Christensenellaceae_R-7_group, Norank_f_Anaerolineaceae and Desulfocapsa, with the relative abundance of 10.03%, 7.38%, 6.92%, 5.58% and 4.29%, respectively. Fisher’ exact test verified that there were 13 genera showing significant difference among the top 15 genera with high abundance in the two ABRs in the third stage, and the difference of 12 genera showed extremely difference (P≤0.001).

In order to investigate the inhibitory effect of the toxic organic matter of phenol on anammox granular sludge, the removal rate of ammonia nitrogen ($ {\rm{NH}}_4^ + $-N) and nitrite nitrogen (NO₂ ⁻-N) in anammox granular sludge under different phenol conditions (50 and 100 mg/L) was studied. The reasons for the degradation of granular sludge performance were analyzed by integrating the secretion of extracellular polymeric substances (EPS) and the change trend of microbial community. The results showed that phenol inhibited the denitrification performance of anammox granular sludge. When the phenol concentration was 50 and 150 mg/L, the removal rate of $ {\rm{NH}}_4^ + $-N was reduced by 15.05% and 24.35%, respectively. Phenol stimulated the secretion of microbial EPS in granular sludge to resist its toxic stress. When the phenol concentration was 50 and 150 mg/L, the total EPS content of granular sludge increased by 43.62% and 57.29%, respectively. The microbial community of the anammox granular sludge changed under different phenol conditions. Under the phenol concentration of 50 and 150 mg/L, the relative abundance of Planctomycetes distributed by anammox bacteria decreased from 41.01% to 38.52% and 33.84%, respectively. Through the Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) prediction analysis, it was found that the key metabolic pathways related to anammox bacteria was inhibited, and the metabolism of functional bacteria related to the denitrification of granular sludge was affected by phenol.

With the increasingly stringent requirements for sewage treatment and the continuous improvement of public health awareness, the nitrate pollution in water body has caused widespread concern in the world. At present, biological heterotrophic denitrification as the main technical means to remove nitrate in water, the carbon source has been the key restricting factor, and the disadvantages of traditional external carbon source have also been found. Therefore, the development of new slow-release carbon source suitable for biological denitrification process has become the focus of attention of researchers at home and abroad. Starting from the necessity of developing slow-release carbon sources for promoting biological denitrification, the types of slow-release carbon sources, the effect of promoting denitrification, the modification methods, the influencing factors of nitrogen removal, the mechanism of action and the characteristics of biofilm were analyzed in detail. The denitrification promoting performance and biofilm community structure of natural slow-release carbon source, modified slow-release carbon source and synthetic slow-release carbon source were compared and revealed. At the same time, the prospects of breaking through the speed limiting steps of reaction kinetics, optimizing skeleton materials and spatial framework, developing new slow-release carbon sources and promoting biological denitrification process were put forward for the follow-up researches, so as to provide reference and basis for the dissemination and application of slow-release carbon sources to promote the efficiency of biological denitrification.

In order to evaluate the performance of activated carbon adsorption and desorption of benzene series, taking the commercial honeycomb activated carbon as the adsorption material, the specific surface area, aperture distribution and surface pore structure morphology of the activated carbon were analyzed by nitrogen adsorption isotherm and scanning electron microscope. The effects of benzene concentration, benzene flow and benzene species flowing through honeycomb activated carbon on their adsorption capacity were evaluated by dynamic adsorption evaluation device and gas chromatography system. The desorption temperature curve of honeycomb activated carbon was also studied by temperature programmed technology. At the same time, the effects of water vapor on honeycomb activated carbon adsorption capacity and desorption temperature curve were investigated. The results showed that the unit saturation adsorption capacity of honeycomb activated carbon to benzene species followed the sequence of xylene > toluene > benzene, with the values varied from 66.5 to 138.1 mg/g. The reason for different adsorption capacities maybe due to the molecular size effect of benzene species. The optimal desorption temperature of benzene species was basically maintained at 175 ºC. The competitive adsorption effect of water vapor could significantly inhibit the unit saturation adsorption capacity of benzene, which was reduced by 36.3% after the introduction of 1.8% water vapor, as the adsorption sites were partly occupied of by water vapor, significantly reducing the adsorption capacity of benzene.

Photocatalysis is a new technology developed rapidly in recent years, which uses solar energy for energy conversion and environmental purification. Molybdenum disulfide has a layered structure and is the representative of transition metal chalcogenides. It has become a good catalyst because of its narrow band gap, many active sites and large specific surface area, and is widely used in the photocatalytic degradation of organic pollutants. The domestic and international research status of different types of molybdenum disulfide-based heterojunction catalysts (metal oxides, bismuth-based materials, silver-based materials, metal sulfides, graphite carbon nitride, graphene oxide) were introduced. The preparation methods and photocatalytic degradation effects of organic pollutants of molybdenum disulfide-based heterojunction catalysts were compared, and their degradation mechanisms were briefly described. The results showed that the coupling effect of molybdenum disulfide could effectively improve the photocatalytic activity of matrix materials. Future research should continue to focus on the development of high efficient, stable and recyclable molybdenum disulfide-based heterojunction catalysts.

Nano zero-valent iron (nZVI) has a large specific surface area, high reactivity and unique core-shell structure, which has a good application prospect in the removal of heavy metals in water. However, nZVI itself has some disadvantages such as easy agglomeration and oxidation deactivation, and its industrial promotion and application are limited. The biochar-supported nano-zero-valent iron (nZVI@BC) composite prepared by loading nZVI on biochar (BC) can overcome the shortcomings of nZVI to a certain extent and improve the reaction activity of nZVI with heavy metals. The research status of nZVI@BC removal of heavy metals from water was reviewed. The preparation of nZVI@BC with different BC materials, the modification of BC and the influence of nZVI modification on the removal performance of heavy metals from nZVI@BC were emphatically introduced. The reaction mechanism of nZVI@BC removal of several typical heavy metals was described. The development prospect of nZVI@BC in removing heavy metals from water was also prospected.

Tannery wastewater has the characteristics of large amount of production, various types of pollutants, complex composition, and containing heavy metals, and has always been the focus of water environment supervision. The tannery production process and the characteristics of wastewater production and discharge were sorted out, and the mainstream water pollution prevention and control technologies in the industry were summarized according to the raw and auxiliary material substitution technology, process control technology, and end treatment technology. Among them, the process control technologies were classified based on target pollutants, and the end treatment technologies were classified according to the requirements of wastewater quality-specific treatment. Based on the various demands for water pollution prevention and control of tannery enterprises with different production processes and different discharge types, 16 sets of technology portfolio were recommended. Finally, the development trend of water pollution prevention and control technologies of the tanning industry was prospected, and suggestions to strengthen the quality-specific treatment of tannery wastewater, strengthen the R&D and promotion of cleaner production technologies, and promote the entry of tannery enterprises into the industrial parks were put forward, with a view to improving the level of water pollution whole-process prevention and control and the green development of the industry, and helping to deepen the fight against pollution prevention and control battle during the 14th Five-Year Plan period.

The effects of CaO addition ratio, airflow rate and bulking thickness on the natural water loss characteristics of municipal sludge treated by CaO were studied. The results showed that sludge water loss rate was proportional to airflow rate and CaO addition ratio, but inversely proportional to bulking thickness. The experimental data were well fitted by the general model based on the Page model with the root mean square error of 6.34%, which could better simulate the natural dewatering process of CaO-treated sludge. The effective water diffusion coefficient of the sludge calculated using the Page model was 9.96×10⁻⁹-1.65×10⁻⁷. The natural water loss time was positively correlated with the CaO addition ratio and airflow rate, and negatively correlated with the bulking thickness. Using the total cost per unit water loss as the evaluation index, the Fmincon function in MATLAB software was applied to calculate the optimal drying parameters under the condition of the lowest total cost per unit water loss. The optimal combination of drying parameters was: CAO addition ratio 0.02, airflow rate 0.6 m/s, sludge accumulation thickness 7 mm.

In order to improve the prediction precision of water quality having time series properties by BP neural network (BPNN), principal component analysis (PCA) was used for characteristic extraction and dimension reduction of the original data. Concentrations of dissolved organic compound (DOC) and total nitrogen (TN), and turbidity were selected as the water quality prediction indices, a three-layer BPNN model was established for prediction, and the prediction performance was analyzed. The results showed that the optimal training-set sizes of concentrations of DOC and TN, and turbidity were 60, 60, and 90 days, while the best BPNN topological structures were 9-12-1, 8-6-1 and 7-13-1, respectively. The optimized BPNN model exhibited favorable prediction performance on the variation trends of concentrations of DOC and TN, and turbidity. In contrast, the prediction performance of DOC by BPNN model was significantly better than that of TN and turbidity, with RMSE, MAPE, and R values of 0.040, 0.66% and 0.867, respectively. This model had a good applicability and precision for prediction of surface water qualities having non-linear characteristics.

Electrokinetic remediation is an effective method to remove heavy metal contaminants from groundwater. The effect of different voltage gradients (1, 2, 3 V/cm) on the removal rate of saturated zone groundwater Cr(Ⅵ) was studied with an initial content of 1 000 mg/kg for 4 days by the electrokinetic remediation method. In addition, the relevant factors in the repair process, including current, pH and redox potential (E_h) of anode and cathode electrolytes, and the concentrations of Cr(Ⅵ) in different positions were monitored. PH, the removal rates of Cr(Ⅵ) and E_h of the saturated zone medium before and after treatments were analyzed The results showed that: 1) The average removal rates of Cr(Ⅵ) increased with the increase of voltage gradient. When the voltage gradient was set at 2 V/cm, the removal efficiency and economy were better. The removal rate increase/energy consumption increase ratio was 0.52. The highest removal rate of 91.41% was observed when the voltage gradient was set at 3 V/cm, and the higher corresponding energy consumption was observed. 2) During the repair process, Cr(Ⅵ) would be enriched near the anode, especially when the voltage gradient was low (1 V/cm). The Cr(Ⅵ) concentration in groundwater near the anode after the reaction was up to 2170.95 mg/L, and the concentration of Cr(Ⅵ) in the medium was 1497.45 mg/kg, with negative removal rate. The concentration of Cr(Ⅵ) in the anolyte showed a tendency to increase first and then stabilize. When the Cr(Ⅵ) concentration was close to 4000 mg/L, it was close to the maximum migration value of the device. Increasing the reaction time had little effect on the recovery rate of Cr(Ⅵ). 3) The decrease of E_h and the increase of pH during the repair process would promote the reduction and desorption of Cr(Ⅵ), which could promote the removal of Cr(Ⅵ).

Taking the natural clay in an enterprise in Changsha as the main raw materials, using the experiment method of water solution polymerization at the room temperature, a new type of sealing material was prepared by mixing bentonite and clay modified with polyacrylamide (PAM), which was used to seal the bottom area of flexible vertical impervious wall construction projects to prevent the groundwater from flowing around the bottom of the high-density polyethylene (HDPE) geomembrane. The influence of three different modifiers and the amount of bentonite on the permeability coefficient of the sealing material and the blocking and adsorption of hexavalent chromium were studied by laboratory experiments. The results showed that the permeability coefficient of the sealing material could be reduced when the bentonite was modified with PAM, while, to a certain extent, the hydroxypropyl methyl fiber and polyvinyl alcohol increased the permeability coefficient of the sealing material. With the increase of the amount of modified bentonite added, the permeability coefficient of the sealing material decreased gradually. In the simulated column migration experiment, the retention effect of the sealing material on pollutants could reach 68.5%. Based on a flexible vertical impermeability wall project in Changsha, no tracer was detected in the downstream receiving well in the tracer dispersion and migration experiment on the area of the built impermeability wall, indicating that the sealing material could effectively prevent groundwater from flowing around the bottom on the engineering application.

At present, the control of greenhouse gases generated by municipal solid waste (MSW) treatment has become one of the key directions of carbon emission reduction. The carbon emissions of MSW treatment in Tianjin from 2009 to 2018 were calculated according to the estimation formula recommended by Guidelines for the Preparation of Provincial Greenhouse Gas Inventories (trial), and the temporal variation characteristic of carbon emissions was analyzed. What′s more, the influencing factors of carbon emissions from MSW treatment in Tianjin were analyzed by using the decomposition identity of influencing factors of carbon emission combined with the improved Kaya identity and LMDI addition decomposition method. The results showed that the carbon emissions of MSW treatment in Tianjin decreased first and then increased from 2009 to 2018, and the carbon emissions were mainly from landfill treatment. Among the factors affecting carbon emissions, the economic output effect (ΔY) had the largest driving effect on carbon emissions of MSW treatment, followed by the carbon emission intensity effect (ΔCF). The MSW discharge intensity effect (ΔWI) and the MSW treatment structure intensity (ΔWS) had a negative effect on carbon emissions. It was proposed that controlling the production of MSW, increasing the proportion of waste incineration treatment and improving the methane recovery rate of the landfill were the main emission reduction directions in the future.

The physiochemical properties and heavy metal pollution characteristics of fly ash from a waste incineration plant in Shanghai were studied and analyzed. The results showed that the fly ash surface area and pore volume decreased obviously, and the chloride content also decreased greatly after refuse classification. Except Zn and Cu, the contents of other heavy metals increased after refuse classification, and the leaching concentration of Pb was far higher than the concentration limit of Standard for Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008), which was of high environmental risk. Therefore, the fly ash must be disposed of harmlessly. Due to the change of Pb, Cd, Zn contents and their unstable forms, the leaching concentrations under acidic condition increased significantly which posed a great potential threat to the environment.

The dissolved organic matter rich in landfill leachate contains hydroxyl, carboxyl, carbonyl and other active functional groups. It is an important carrier for the migration of heavy metals in environmental media. Due to different sources of landfill leachate, there are also significant differences in DOM component composition, types and contents of heavy metals. The common reaction between DOM and heavy metals is mainly complexation whicn is the key to affect the forms and environmental behavior of DOM and heavy metals in leachate. However, due to the complexity of DOM complexation process and in order to analyze the complexation effect, an effective characterization method and a complexation model based on it are important technical means to clarify the complexation mechanism between DOM and heavy metals in landfill leachate. The authors focused on the DOM characterization methods such as fluorescence technology, UV-Vis spectroscopy and infrared spectroscopy and common complexation models, and summarized the influencing factors such as pH, DOM composition and heavy metal ions in the complexation process, in order to provide theoretical guidance for pollution remediation technology and revealing the morphological transformation law of heavy metals in leachate .

With the rapid social and economic development around Bohai Region and the significant increase of population, the municipal solid waste (MSW) production has increased year by year, and the pollution caused by it has a significant impacts on the urban development, the environment and the life citizens' lives. Therefore, an accurate prediction of MSW production is very important for subsequent treatment and disposal. Based on this, the current situation of MSW production in ten typical cities around Bohai Sea from 2005 to 2019 was analyzed, and the ARIMA model was established by MATLAB to predict the MSW production in 2020-2024. The prediction results showed that from 2020 to 2024, the growth range and speed of the MSW production of ten typical large cities around Bohai Region were different, but on the whole, the MSW production exhibited an increasing trend from 2020 to 2024, which was consistent with the growth trend of that from 2005 to 2019. The MSW production in the ten cities, Tianjin, Dalian, Yingkou, Panjin, Jinzhou, Huludao, Binzhou, Weifang, Dongying and Yantai in 2024 would be 3 651 600, 2 786 500, 627 300, 303 400, 1 200 500, 498 100, 510 200, 814 100, 887 600 and 1 376 800 tonnes, respectively.

In order to study the pollution and spatial distribution characteristics of soil heavy metals in Lhasa, the contents of 8 heavy metals in 20 surface soil samples in the main urban area were analyzed and determined. And the Nemerow comprehensive pollution index and potential ecological hazard index were used to evaluate the environmental quality and ecology risk. The research results showed that the average values of Cu, Zn, Cr, Ni, Pb, Cd, As, and Hg in the soil are 0.92, 1.02, 0.85, 0.83, 0.73, 0.83, 1.28, and 0.8 times of the Lhasa background values, All of them meet the grade Ⅱ standard of National Soil Environmental Quality Standard (GB 15618-1995), among which Zn and As have a higher rate of exceeding the standard, 45% and 95% respectively. From the spatial distribution map of heavy metals, the distribution of elements presents a certain pattern, which mostly presents a dot pattern. Among them, Ni was evenly distributed, and other elements have high value areas. The accumulation status of heavy metals in the study area was similar to the track of human activities. Except for the single pollution index of Zn and As, which was slight pollution, all other elements are non-pollution. The average value of Nemerow comprehensive pollution index was 1.24, which belongs to slight pollution; The mean value of RI was 85.96, which was low ecological hazard, and Hg and Cd were the main risk factors. The accumulation of Cu, Zn, Pb, and Cd were mainly from natural sources, partly affected by transportation activities; the accumulation of As were mainly due to the high natural background value; the accumulation of Hg was affected by both natural sources and industrial sources; the accumulation of Ni and Cr were controlled by natural factors.

Taking an electroplating site in Suzhou City as the research object, the pollution degree of eight heavy metals (As, Cd, Pb, Cu, Ni, Zn, Hg, Cr(Ⅵ)) in soil samples was evaluated by using Nemero index method, and it was clear that the soil of the electroplating plant was polluted by Ni and Cr(Ⅵ). Based on the health risk model and Kriging interpolation method, the three-dimensional spatial health risk distribution of Ni and Cr(Ⅵ) in soil was studied. The results showed that the carcinogenic and non-carcinogenic risk levels of Ni and Cr(Ⅵ) in Workshop Four (rack plating of nickel and chromium) exceeded the acceptable threshold. The pollution of Ni and Cr(Ⅵ) showed a pattern of point source diffusion. The farther the distance from Workshop Four (polluted area), the lower the pollution degree. From the vertical perspective, both Ni and Cr(Ⅵ) presented the behavior of migration from the surface to the deep soil. Therefore, it was necessary to remediate the soil before development and utilization.

The efficient petroleum hydrocarbon degrading bacteria were isolated and screened from the polluted soil of an abandoned chemical plant in Lianyungang City. The physiological and biochemical characteristics of the strains were studied, sequenced and identified. The related environmental factors of diesel fuel degradation were analyzed by single factor test. The results showed that four strains of diesel degrading bacteria were isolated from polluted soil. After sequencing and homology comparison, the highest homology with the four strains were Enterobacter_cloacae (HY1), Achromobacter_pulmonis (HY2), Pseudomonas_taiwanensis (HY3), Pseudomonas_aeruginosa (HY4), and the homology was more than 98%. The four strains had different abilities of producing surfactant and degrading diesel oil. HY1 and HY2 had the highest degradation rate of diesel oil. When the diesel oil concentration was 0.5% and the treatment time was 20 days, the degradation rate of diesel oil by the two strains was more than 37%. After optimizing the degradation conditions by single factor experiment, when the diesel oil concentration was 0.5% and the degradation time was 8 days, the optimal degradation conditions of HY2 and HY1 were initial pH 7, shaking table speed 180 r/min and inoculation amount 3%-4%. At this time, the degradation rates of diesel oil by the two strains were 40.15% and 43.87%, respectively. This study can enrich the strain information of petroleum hydrocarbon degrading bacteria and provide strain resources and data support for the remediation of petroleum hydrocarbon contaminated soil.

Tobacco is an important economic crop which is readily to uptake cadmium (Cd) from soils, rendering it to be one of the main source of Cd to human bodies. Therefore, reducing Cd content in tobacco leaves through regulation and control measures is important to ensure tobacco quality, safety and human health. The soil Cd passivation technologies to reduce Cd content in tobacco were summarized, and the passivation mechanism of passivators, including adsorption, ion exchange, precipitation, complexation and ion antagonism, was expounded. The factors affecting Cd content in tobacco were also analyzed, including soil Cd concentration and chemical forms, soil pH, redox potential, organic matter concentration, cation exchange capacity, and competitive metal ions. The passivation efficiencies of normal passivators and the parameter conditions in the applications were illustrated, including lime, hydroxyapatite, metal oxides, biochar, organic fertilizer, sepiolite, zeolite and bentonite. Some suggestions were proposed to provide basic data and technical reference for the reduction of Cd content in tobacco, including clarifying the standard system of tobacco Cd content, developing new passivation materials and using molecular biology technologies, etc.

The constructed wetland has been widely used in the remediation of water environment pollution due to its low investment cost, efficient water purification and harmonious landscape. However, there is a lack of complete standardized route for the configuration of plants in constructed wetlands under different conditions. 465 hydrophyte combination data in 210 constructed wetland literatures were screened and analyzed by using the method of literature retrieval and analysis. Based on the analysis results, a five-step hydrophyte configuration route for constructed wetland was constructed, including single species determination, configuration and collocation, system construction, landscape configuration, and space configuration. The technical content of each configuration step and the proposed list of the available hydrophytes were put forward. In the step of single species determination, five species of aquatic plants (Acorus calamus, Canna indica, Phragmites communis, Typha orientalis, Iris tectorum) were identified as the predominant functional hydrophyte. In the step of configuration and collocation, hydrophyte combinations were made according to the nutrient salt concentration of incoming water. In the step of system construction, different types or winter hydrophyte were supplemented. In the step of landscape configuration, hydrophyte was supplemented according to flower color, flowering period, height and ornamental characteristics. In the step of space configuration, the space configuration of hydrophyte was made from nutrient salt removal effect, landscape effect, biodiversity of artificial wetland system, and resistance to hydraulic scouring. This hydrophyte configuration route can provide a reference for the standardization of the hydrophyte configuration during constructed wetland design.

Ecological slope protection can effectively reduce a series of geological environmental problems caused by engineering construction, such as soil erosion and landslides. The vegetation concrete ecological restoration technology, which is one of the common ecological slope protection technologies in China, has become mature after continuous researches and applications. The theoretical basis of ecological restoration of vegetation concrete technology were discussed, the research and development experience of vegetation concrete technology were expounded. The main contents of vegetation concrete technology was introduced from the aspects of substrate ratio, species selection and construction technology, and the technical advantages were summarized. The research system of vegetation concrete technology was summarized and the research progress of vegetation concrete ecological restoration technologies was reviewed from four aspects of physical, chemical, microbial characteristics of habitat substrate and slope protection plants. The problems for improvement of vegetation concrete ecological restoration technology were analyzed, and the development prospects of vegetation concrete ecological restoration technology were proposed in terms of the construction technology, conservation measures and soil improvement.

Ecosystem services are irreplaceable for human well-being. Based on the method of literature review, the research progress and trend of ecosystem services were summarized. Firstly, the concept and connotation of ecosystem services were expounded. Secondly, the research progress of ecosystem services were combed in terms of the monetary value evaluation of ecosystem services, the supply-demand balance and transfer of ecosystem services, and the trade-offs and synergies of ecosystem services in China and abroad. Thirdly, it was proposed that the internal relationship of ecosystem pattern-process-function-services would be the focus of ecosystem services research, the supply-demand and spatial transfer of ecosystem services would become an important research direction, the trade-offs and synergies of ecosystem services would be an important part of ecosystem management research, and the feedback mechanism of ecosystem services and human well-being would be further studied. The research would help to scientifically understand the supporting role of ecosystem services for the sustainable development of human society, and to promote the application of ecosystem services research results to practice.

To address the problematic time weights of panel data in the evaluation of carbon emission efficiency, a partial-order set evaluation model was used to evaluate the carbon emission efficiency of China. In this model, it was not necessary to know the specific weight values of the indicators, but only the weight order was needed. By collecting the panel data of 30 Chinese provinces (autonomous regions and municipalities) from 2000 to 2017, calculating each year′s carbon emission efficiency, and sequencing the weight values in time reverse order, the carbon emission efficiency was evaluated. The results showed that the carbon emission efficiency was the highest in East China, followed by the Central China, and the worst in Northwest. The factors affecting the carbon emission efficiency in each region were different, which required that specific carbon emission policies should be developed according to local conditions. The carbon emission efficiency of each region tended to be aggregated, and the local carbon emission policy would not only affect the carbon emission effect of the region, but also affect the carbon emission of the adjacent areas, so, it was necessary to strengthen the cooperation of carbon emission reduction among all the regions.

By sorting out the relevant policies and control measures for the elimination of old vehicles in Beijing since 2011, the emission factor method was used to calculate the emission reduction and environmental benefits of motor vehicle pollution, the role of the policies was analyzed. Combined with the current emission situation of motor vehicle pollution in Beijing, as well as the needs of air quality improvement and carbon emission reduction, the development directions of the policies for the elimination of old vehicles in the future were put forward. The results showed that the implementation of the elimination policies of aging vehicles in Beijing had accelerated the adjustment and optimization of Beijing's motor vehicle structure, the reduction of air pollutant emissions was achieved even with the continuous increasing number of motor vehicles, and good environmental benefits had been achieved. Based on the variation of motor vehicles structure and emissions, the elimination and subsidy policies of aging vehicles could set differentiated and subdivided subsidies to continuously improve the directions and accuracy of the policies. For the future policy directions, it was necessary to further strengthen the formulation of renewal plans based on the emission differences of different vehicle models. For the key vehicle units, it was useful to promote the adjustment of motor vehicle structure and the development of new energy in combination with the management of key carbon emission units in Beijing. On the basis of these policies, the coordinated control of carbon dioxide and air pollutants emitted from vehicles would be achieved.

Industrial parks are not only the gathering place of enterprises, but also the high incidence of pollution. So the ecologically oriented development of industrial parks is of great significance to regional green development. In view of the complex relationship among economic, energy and environmental systems in the development of industrial parks, a system dynamics model of the economy, energy, and environment (3E) was developed, based on the effectiveness of the model, a national eco-industrial park was taken as an example for dynamic simulation. According to the current situation of the case park, the development trend of the industrial park was predicted by providing six scenarios, i.e. benchmark, energy conservation and carbon reduction, pollution reduction, energy structure adjustment, moderate economic growth and increasing energy conservation and carbon reduction. Then, the prediction results were evaluated according to the Standard for National Demonstration Eco-industrial Parks (HJ 274-2015). The results showed that the 3E system dynamics model of industrial parks could be used to predict the development trend of the parks. Through the regulation of key factors such as economic growth rate, energy consumption intensity, energy structure and emission reduction factors, the development scenarios could be optimized. The park development growth rate and the energy conservation and emission reduction intensity under certain conditions could be put forward, so as to provide scientific guidance and decision support for park planning and development.

To systematically analyze the environmental impact, technological progress and economic cost of the photovoltaic industry, firstly the life cycle assessment (LCA) was conducted to quantitatively analyze the environmental impacts of the industry. Based on the results of LCA, the technology progress assessment model of photovoltaic industry was constructed and the technology progress rates were calculated. Then the investments of equipment in photovoltaic industry were combined with the results of the environmental impact assessment to calculate the cost reduction rates. At the same time, the photovoltaic electricity price subsidy policies in recent years were sorted out to calculate the subsidy decline rates. Finally, the photovoltaic industry technological progress and economic cost were comprehensively analyzed. The results showed that the photovoltaic industry had an environmental impact potential of 83.83 Pt when producing 1 kWp polysilicon photovoltaic modules, among which high purity polysilicon, silicon wafer, cell and module accounted for 43.05%, 16.24%, 14.84% and 25.87%, respectively. Taking 2016 as the base year, the technological progress rates of the photovoltaic industry in 2017, 2018, 2019 and 2020 were 5.20%, 8.98%, 12.48% and 20.91%; the cost reduction rates were −5.81%, −21.05%, −25.23% and −32.63%; and the subsidy decline rates were −15.60%, -30.36%, −40.46% and −51.33%, respectively. During the same period, the decline rates of photovoltaic subsidies were greater than the rates of technological progress and cost decline. The rates of technological progress and cost decline were more synchronized after 2017, reflecting that the decline in subsidies could force companies to adopt more advanced technologies to reduce costs to a certain extent.

shIn the process of natural gas exploitation, a large amount of drilling solid wastes are produced, which contains toxic and harmful substances such as petroleum hydrocarbon, inorganic salt and refractory organic matter. The solid wastes produced by different well types, different well sections at typical drilling sites in five blocks of Sulige Gas Field were sampled, their performance characteristics and pollution characteristics were analyzed, the technical parametshers of the integrated process of classified management and control, stabilization pretreatment and high-temperature incineration and oxidation of drilling solid wastes were studied, and the variations of drilling solid waste pollutant concentration before and after treatment with this technology were analyzed. The results showed that the concentrations of pollutants in the solid wastes and leachates of shallow surface drilling met the requirements of the maximum allowable limits of Integrated Wastewater Discharge Standard (GB 8978-1996) after treatment by fine stabilization pretreatment technology. The reduction rate of petroleum hydrocarbons in drilling solid wastes in the deep well section was more than 98.6%, and the concentrations met the screening value requirements of category Ⅱ of construction land soil pollution in Soil Environmental Quality Risk Control Standard for Soil Contamination of Development Land (GB 36600-2018). In the meanwhile, the concentrations of heavy metals and organic matter in the residue decreased significantly, which were in line with the limit requirements of GB 8978-1996. Moreover, the volume of solid wastes was reduced by 41.2%. The integrated treatment technology of ‘classified control-stabilization pretreatment-high temperature oxidation’ could solve the problem of solid wastes treatment and disposal of natural gas exploitation and drilling from the source. Compared with the existing traditional unclassified treatment technologies, the overall cost of the integrated technology was reduced by 52%, which had a good prospect for promotion.

The spatial and temporal distribution characteristics of PM_2.5 were analyzed at the township scales with the monitoring data from 261 automatic air quality monitoring stations of Shijiazhuang City in 2018, using the spatial analysis method of geographic information systems (GIS). The correlation characteristics between PM_2.5 and its precursors (SO₂, NO₂) were also discussed. The results showed that the annual concentration of PM_2.5 in 261 townships was 41-112 μg/m³ in 2018, which exceeded the secondary standard limit of Ambient Air Quality Standards (GB 3095-2012). The concentration of PM_2.5 was generally lower in the mountainous area with higher terrain in the northwest than that in the plain area in the southeast, and it was lower in the main urban area than that in the surrounding counties (cities and districts). In respect of seasonal variation, the average concentrations of PM_2.5 in Shijiazhuang City was the highest in winter and lowest in summer. Monthly average concentrations of PM_2.5 showed that it was from January to March and from November to December that the data of PM_2.5 were higher than those of the rest months of the year, August was the month that with the lowest monthly average concentration. The concentration of PM_2.5 was significantly positively correlated with the concentration of both SO₂ and NO₂ in the observation period. The degree of the correlation was the weakest in summer and the strongest in winter, and the more serious the pollution was, the more significant the degree of regional correlation was.

In order to understand the pollution characteristics and sources of O₃ in downwind urban areas affected by coking, a study was carried out based on the monitoring data of O₃ and meteorological parameters (temperature, etc.) at six national monitoring sites in Linfen City, and VOCs at Beidajie site in 2019. The results showed that the 90th percentile (MDA8-90th) of the maximum daily 8-hour moving average (MDA8) of O₃ was 204 μg/m³ in Linfen City in 2019, ranking first among 11 cities in Shanxi Province. There were 103 days when O₃ concentrations exceeded the standard and were mainly concentrated in May-September; MDA8 began to rise in February, reached the maximum in June, and then decreased month by month; O₃ concentration showed a single-peak diurnal variation, with a peak between 14:00 and 16:00. MDA8 was positively correlated with daily maximum temperature (T_max) and negatively correlated with daily minimum relative humidity (RH_min). When T_max was greater than 22 ℃ or RH_min was less than 55%, O₃ concentration may exceed the standard. The analysis of O₃ formation potential (OFP) of VOCs showed that ethylene had the highest OFP, accounting for 44.5% of the total OFP, which was the key active species leading to O₃ pollution. The emissions from the use of Liquefied petroleum gas (LPG), vehicle exhaust, and coking activities contributed to O₃ pollution in Linfen City. Among the six national monitoring sites, Chengnan and Tangyao Hotel contributed the most of O₃ pollution at all levels in Linfen urban area. At both sites, 77% of O₃ exceeding the standard concentration occurred when the south and southwest wind was blowing, while16.6% of O₃ exceeding the standard concentration at Chengnan site occurred when the wind speed was greater than 3 m/s; the frequency of naphthalene, as a typical tracer of coking, appearing higher than its mean value in the southerly direction was 30.4%, which indicated that the unreasonable industrial layout made the atmosphere in Linfen City affected by the coking area, and O₃ concentration was more likely to exceed the standard when the southerly wind blew. The pollution emission in Xiangfen, Hongdong, Yicheng and Fushan counties contributed to O₃ pollution in Linfen City. The above results showed that O₃ pollution in the urban area of Linfen City was not only affected by the local generation but also by the transportation of polluted air masses containing high concentration of NO_x and VOCs emitted by coking and steel plants in the above four counties. Therefore, joint prevention and control with the upwind areas affected by coking should be paid attention to while strengthening the control of local LPG use and vehicle exhaust emissions in Linfen urban area.

Based on the hourly observation data of six conventional pollution parameters provided by five state-controlled environmental monitoring sites in Nanyang City from 2015 to 2019, and combined with the surface meteorological elements data of Nanyang Station, the national benchmark station, the temporal and spatial distribution characteristics of ozone pollution and the influence of meteorological factors were investigated. The results showed that the ozone pollution in Nanyang City became serious from 2015 to 2019, and the average daily maximum 8 h sliding concentration (MDA8) of O₃ increased from 145 μg/m³ in 2015 to 181 μg/m³ in 2019, with an increase of more than 25%. O₃ pollution displayed a distinct seasonality, where the maximum values occurred in summer. As for spatial distribution, the O₃ pollution presented obvious block distribution characteristics, and its high value appeared in the central area of the city. Meteorological conditions were important factors affecting the concentration of O₃ in Nanyang City. Under high temperature, low humidity and high visibility conditions, it was easy to form serious ozone pollution. With the increase of wind speed, the O₃ concentration increased first and then decreased. In June 2019, the O₃ pollution in Nanyang City was serious, and the O₃ exceedance rate was more than 63%. During this period, there were three ozone pollution processes. The pollution events were related to favorable meteorological conditions and strong pollution emission intensity.

There are some technology problems of routine electrostatic precipitator, such as difficult charging of fine-particle dust, anti-corona, and dust re-entrainment. These technology problems limit the further improvement of dust removal efficiency. The efficiency deep improvement technologies of electrostatic precipitator were studied in detail. Firstly, the dust-removal efficiency deep improvement process was put forward, which included dust pre-collection in inlet smoke box, two-dimensional dust collection at the tail of electric fields, and dust anti escape technology in outlet smoke box. Secondly, the "W" shaped and trapezoid net-like dust collection devices perpendicular to the air flow direction were developed, which significantly increased the dust collecting area of electrostatic precipitator and solved the problem of dust re-entrainment. At last, the efficiency deep improvement technologies of vertical airflow electrostatic precipitator were applied on 630 MW coal-fired unit project. The application results showed that the dust concentration could be controlled to be lower than 10 mg/m³ at the outlet of electrostatic precipitator without changing the shape and size of the electrostatic precipitator and the number of electric fields. The dust concentration at the outlet of electrostatic precipitator was reduced from 14.4 mg/m³ before transformation to 6.5 mg/m³ by applying the technology. And the efficiency improvement range was as high as 54.9%, which was equivalent to that of the low-temperature electrostatic precipitation technology. Apparently, the dust concentration could achieve ultra-low emissions by applying the technology.