Enzymatic pretreatment can promote the degradation of organic components in sludge and thereby enhance its anaerobic digestion efficiency. Nevertheless, the high cost of commercial enzymes and the limited hydrolysis efficiency of single enzymes restrict their large-scale promotion and application. In this study, a strain of fungus, Aspergillus tamarii FM2, was isolated and screened from excess sludge (ES)， which could rapidly produce compound enzymes using multi-source organic solid wastes. The hydrolysis and anaerobic digestion efficiency of ES were enhanced by optimizing enzyme production and hydrolysis conditions, and the underlying mechanism was systematically elucidated. The results showed that soybean residue was the optimal solid-state fermentation substrate for Aspergillus tamarii FM2. The optimal enzyme production conditions were determined as follows: a temperature of 30 ℃, a moisture content of 90% of fermentation substrate, and a fermentation duration of 3 days. Under these conditions, the activities of protease, amylase, and cellulase in the compound enzyme-containing fermentation substrate reached 89.8, 89.0, and 17.2 U/g, respectively. The optimal dosage of compound enzyme substrate for pretreatment was 10%. At this point, the soluble chemical oxygen demand and soluble protein content in ES increased by 41.9% and 23.3%, respectively, compared with the control group. Further mechanism analysis revealed that compound enzyme pretreatment effectively promoted the dissolution of organic matter in ES and significantly improved the biodegradability of the pretreated liquid. Meanwhile, it disrupted the surface structure of ES. The preferential degradation order of the main constituents in the pretreated solid changed from structural carbohydrates to protein-amide substances, with the relative content of protein-N decreasing from 71% to 63%. After compound enzyme pretreatment, the methane yield from ES anaerobic digestion reached 209.0 mL/g, which was 84.0% higher than that of the raw sludge. Preliminary analysis of operational costs showed that, compared with other processes, the integrated process of compound enzyme preparation combined with hydrolytic pretreatment for enhancing sludge anaerobic digestion featured low cost and low energy consumption in operational economy, and presented high potential for popularization and practical application.

Taking perishable organic waste as the main framework, a cross-linked system of “acrylic acid grafting+methylene diacrylamide” was constructed, and sodium dihydrogen phosphate/magnesium sulfate was introduced for flame retardant regulation. Meanwhile, the water absorption and water retention, mechanical properties and flame retardancy of gel were systematically evaluated. The research results showed that the gel water retention rate was equal or over 30% and the swelling rate within 72 hours was 1.91-2.44 g/g. Under simplified loading conditions, the deformation of a 300 g load was approximately 0.5 cm. Horizontal burning met the HB grade flame retardant standard, and vertical burning met the V-0 grade. In this study, kitchen waste has been used to replace high-purity natural polymer materials to achieve low-cost resource utilization. The mechanism of “high water content thermal barrier+acid source carbon promotion/inorganic heat absorption” has been coupled in the same system, and the flame retardancy evaluation has been completed based on standardized criteria.

Small-scale waste treatment facilities for municipal solid waste in remote areas of China (such as high-altitude, severely cold, and island regions) face bottlenecks including poor operational stability, difficulty in meeting pollutant emission standards, and high operation and maintenance costs. Based on an analysis of the current status of small-scale waste treatment technologies at home and abroad, the advantages and disadvantages of mechanical grate furnaces and pyrolysis gasification technologies were compared, and pointed out that grate furnace technology had greater reliability in dealing with waste with high moisture content and low calorific value. Given the characteristics of low thermal capacity and large fluctuation in small-scale facilities, systematic research directions for optimization were proposed. In terms of combustion system optimization, the focus is on waste shear crushing pretreatment, lightweight air-cooled grates, and high-performance composite refractory materials. For intelligent control, machine learning can be employed to establish a combustion prediction model based on image recognition, enhancing the system’s disturbance rejection capability. Regarding flue gas purification, a deep dry deacidification process using sodium bicarbonate and an integrated removal technology with catalytic filter media can be developed to simplify the process flow. For fly ash disposal, a synergistic treatment approach of “agglomeration and weight gain plus in-situ return to the furnace” can be explored. The research findings can provide systematic technical support for the construction of environmental infrastructure and the enhancement of governance capacity in remote areas of China.

A pilot test platform was established in the municipal solid waste incineration power plant, and the effects of sodium bicarbonate flue residence time, excess coefficient and dust collector pressure difference on the removal of HCl and SO₂ in the flue gas by fine sodium bicarbonate powder were investigated at the reaction temperature of 145-205 ℃, and the deacidification effect of sodium bicarbonate was compared with that of ordinary slaked lime and high-specific surface area slaked lime. The results showed that the overall efficiency of chlorine removal by sodium bicarbonate was higher than that of desulfurization. Increasing the reaction temperature, extending the residence time or raising the pressure drop across the dust collector all contribute to reducing the excess coefficient of sodium bicarbonate and improving the overall deacidification efficiency, with a particularly notable impact on SO₂ removal. However, the optimization of the operation would lead to a corresponding increase in operating costs, an economic assessment was required.

In the flue gas purification system of hazardous waste incineration, the quench tower is used for rapid cooling of the tail flue gas to prevent the reformation of dioxins within the temperature range of 200-500 ℃. Aiming at the problems of corrosion and liquid leakage caused by droplet wall adherence in the quench tower of hazardous waste incineration, the quench tower of a hazardous waste incineration plant has been taken as an research object. Based on the Euler-Lagrange method, a numerical calculation model of the quench tower was established by considering the heat and mass transfer between droplets and flue gas and tracking the movement trajectories of droplets. The effects of nozzle position, atomization angle, and atomized particle size on flue gas cooling in the quench tower were mainly investigated, and the droplet wall adherence under different operating conditions was statistically analyzed. The results showed that the atomized particle size had the most significant effect on the flue gas cooling performance. When the atomized particle size was reduced from 250 μm to 123 μm, the average outlet flue gas temperature decreased from 515 K to 446 K. The atomization angle directly affected liquid accumulation and droplet wall adherence in the tower, and comprehensive analysis indicated that 30° was the suitable atomization angle for this quench tower. The flue gas cooling rate in the upper region of the tower could be accelerated by increasing the spray gun height. The research results provide certain guidance for improving the flue gas cooling rate and reducing the probability of droplet wall adherence in the tower.

In the current analysis process of NOx emissions from waste incineration plant, convolutional neural networks are mainly used to predict NOx emissions. Due to the fact that variable data features can only be captured from the spatial dimension, the prediction results have relatively large errors. Therefore, a prediction model for NOx emissions from waste incineration plant based on spatiotemporal convolutional network optimization was proposed. By mutual information analysis, the key process variables strongly correlated with NOx emissions were screened out. The persistent time series data were transformed into multiple intrinsic mode function components through ensemble empirical mode decomposition,extracting multi-scale features and suppressing noise. An intelligent prediction model was established based on multi-scale convolutional neural network and long short-term memory network. By capturing the temporal and spatial variation characteristics of the data, the high-precision prediction of future NOx emission concentrations was achieved. The experimental results showed that the relative error of the model prediction could remain stable within 3%, demonstrating its superior performance. This model not only enhances the accuracy of emission prediction, but also provides reliable data support for the real-time optimization and emission regulation of the incineration process.

Aiming at the leachate treatment challenges caused by the mixing of rainwater and sewage in landfills under different operating conditions, this study was guided by the pollution control throughout the whole life cycle of landfills. Three typical municipal solid waste landfills in Ganzhou, Hefei and Shenzhen in southern China were selected, and the key technologies for rainwater-sewage separation in landfills were systematically analyzed around three typical engineering scenarios, such as newly-built landfill areas, closure treatment, and waste excavation & restoration. By standardizing the calculation of rainwater and leachate flow rates, scenario-specific technical schemes were proposed: the collaborative control technology of “horizontal zoning + vertical zoning + three-dimensional anti-seepage” was adopted for newly-built landfill areas， the comprehensive treatment measures of “stockpile reshaping + full-area drainage + three-dimensional anti-seepage”were implemented for closed landfill areas， and the combined measures of “zoned excavation + dynamic membrane coverage +vertical barrier” were applied for excavated landfill areas. The results showed that the constructed scenario-specific technical system could significantly reduce the leachate generation from the source, lower the subsequent leachate treatment load and operational costs, and effectively prevent and control the pollution risks to soil and groundwater. The research results can provide practical technical basis and engineering reference for the pollution prevention and control throughout the whole life cycle of municipal solid waste landfills.

Landfilling is one of the most widely used waste disposal methods in China, but it may have significant impacts on the surrounding environment during long-term operation, especially the potential threat posed by the migration of leachate pollutants to the surrounding groundwater and soil quality. Two typical landfills in Hunan province were selected as the research object to systematically analyze the environmental quality of the surrounding groundwater and soil, as well as the potential health risks posed by heavy metal pollution to the surrounding residents, by using the single-factor pollution index, Nemerow comprehensive index method, and health risk assessment model. The results show that arsenic is the dominant carcinogenic risk element in groundwater pollution in the two counties, with a contribution rate of 82.1%-87.9%. Soil pollution is prominent in County B, with the average single-factor index of zinc exceeding 3, indicating severe pollution. Arsenic in soil poses a significant carcinogenic risk, with a value of 1.19×10-5 in County B, and oral ingestion is the main route. The research results provide a reliable scientific basis for environmental supervision, pollution prevention and control, and ecological restoration of landfills, and are of great significance for ensuring regional environmental safety and human health.

To improve the resource utilization efficiency of combustible solid waste and explore efficient low-carbon production paths for hydrogen energy, an integrated energy-exergy-environment (3E) assessment model was constructed for a commercial combustible waste gasification poly-generation (CWGP) system to evaluate its technical performance and environmental impacts. Through sensitivity analysis, the global optimal operating parameters were determined as follows: a gasification temperature of 950 ℃, a steam-to-waste ratio of 0.5, and an equivalence ratio of 0.30. Under these conditions, the total yield of CO and H2 was 488.7 kmol/h, and the total thermal efficiency of the system reached 64.13%. The overall exergy efficiency was 58.69%, with the gasification reaction unit (GSF) being the largest source of exergy destruction (56.09%) due to the strong irreversibility of high-temperature chemical reactions. Life cycle assessment (LCA) results showed that treating 1 ton of solid waste yielded 89.7 kg of hydrogen with a carbon capture rate as high as 91.1%, and a total life cycle global warming (GW) potential of 413.14 kg. Normalization analysis further identified ecotoxicity as the primary environmental load of the system, stemming from the external electricity consumption of 205.1 kWh/t, which contributed to the majority of environmental indicators besides GW. In conclusion, enhancing process thermal efficiency to reduce auxiliary power consumption and introducing renewable energy supply are the core paths for synergistically reducing the carbon footprint and environmental toxicity of the poly-generation system, thereby achieving a green transition of the process.

A typical chlorinated hydrocarbon contaminated site in Tianjin was taken as the research object, and the full-life-cycle environmental impacts of two soil remediation schemes were evaluated based on engineering measured data and the life cycle assessment (LCA) method. The survey area of the site is 49 691.52 m2, with soil pollution involving 5 types of pollutants such as tetrachloroethylene and trichloroethylene, and groundwater pollution involving 4 types of pollutants such as trichloroethylene and vinyl chloride. The total remediation earthwork volume is 39 236.7 m3, and the groundwater remediation volume is 10 118.0 m3. The remediation target values were determined based on the health risk assessment model in HJ 25.3—2019 Technical Guidelines for Risk Assessment of Soil Contamination of Land for Construction, combined with the risk control values calculated inversely using plot exposure parameters. By quantifying indicators such as material consumption, energy consumption, and solid waste generation, the carbon emission characteristics and environmental benefits of the two schemes were compared and analyzed. The results showed that there were significant differences in carbon emission intensity (in terms of carbon dioxide equivalent) per cubic meter among different remediation technologies. In-situ chemical oxidation (ISCO) had the lowest intensity (0.38 t/m3), cement kiln co-processing (CKC) had the highest intensity (0.57 t/m3), while thermal-enhanced soil vapor extraction (TE-SVE) (0.54 t/m3) and in-situ thermal desorption (ISTD) (0.49 t/m3) were in the middle. Scheme 1 adopted the combined technology of ISTD + ISCO, with a total carbon emission of 32 301.52 t and a remediation cost of 94.585 4 million yuan. Scheme 2 adopted the combined technology of CKC + in-situ TE-SVE + ISCO + groundwater pump-and-treat, with a total carbon emission of 27 050.41 t, which was 16.3% lower than that of scheme 1, and the remediation cost was 69.994 0 million yuan, which was 26.0% lower than that of scheme 1, reflecting the remediation advantages of “low carbon + high efficiency”.

Under the dual context of tightening environmental standards and preferential subsidy retrenchment in the electricity market, enhancing the economic robustness of denitrification systems in municipal solid waste (MSW) incineration power plants is of paramount importance. Based on life cycle cost (LCC) theory, this study develops a dynamic economic quantification model for the SNCR-SCR integrated denitrification system. The model specifically incorporates the unique operating conditions of MSW flue gas, such as high corrosiveness, alkali metal poisoning, and steam-extraction reheating, spanning initial investment, routine operation, unplanned shutdown penalty costs, and hazardous waste disposal. A project with a capacity of 2×1 000 t/d was selected for empirical research. The dynamic accounting and 10 000 Monte Carlo uncertainty simulations demonstrated that the integrated process exhibited superior cost-effectiveness within its life cycle under the 50 mg/m3 ultra-low emission constraint, with the expected mean of the dynamic net cost of denitration per unit of waste was 23.3 RMB/t. Global sensitivity analysis indicated that the policy subsidy retention coefficient (variance contribution of 48.6%) and the raw inlet NOx concentration (variance contribution of 19.0%)were the critical driving factors of the system’s economic robustness. Accordingly, a “dual-dimensional” robust control zone was defined, in terms of technical working condition, the inlet NOx concentration should be stabilized between 240 mg/m3 and 360 mg/m3 via front-end pre-sorting and combustion optimization. While in terms of policy-market, the compliant subsidy price should be secured above 0.014 RMB/kWh. Finally, the proposed synergistic optimization framework integrated catalyst life extension, system energy conservation, and intelligent control, which would be projected to reduce the annual operating cost by approximately 13.7%-14.4%. This study provides reference value for advancing refined asset dynamic management in the traditional waste-to-energy industry.

To address the environmental risks and resource wastage associated with the long-term stockpiling of high-alumina coal gangue in the Jungar mining area, a three-level synergistic integrated technology system of short-flow aluminum-silicon co-smelting-targeted enrichment and recovery of trace elements-high-value material conversion of calcium silicate residue was proposed, aiming to overcome the systemic limitations of traditional single-element extraction technologies, such as low resource utilization efficiency and high yield of secondary solid waste. By constructing a coupled model of material flow analysis and life cycle assessment, the resource utilization efficiency, environmental benefits and economic feasibility of this system were quantified. A simulation was conducted based on a demonstration scale with an annual processing capacity of 200 000 tons. The results indicated that the integrated system achieved a comprehensive resource utilization rate of 92.3%. It could annually produce approximately 70 000 tons of aluminum-silicon alloy (aluminum + silicon≥95%) and 1.04 tons of high-purity metallic gallium (purity≥99.9%), while fully converted 130 000 tons of calcium silicate residue into high-performance foamed ceramics (compressive strength≥3.5 MPa), which realized near-zero discharge of solid waste. Comparative analysis of life cycle assessment revealed that, compared to the conventional one-step acid leaching process, the global warming potential of the integrated technology route reduced by 38.5%, the cumulative energy demand reduced by 40%, and the acidification potential and eutrophication potential reduced by 42% and 34%, respectively. This study provided a engineering-feasible systematic solution and quantitative decision-making basis for the large-scale, high-value-added, and low-carbon utilization of coal gangue in mining areas.

During the 14th Five-Year Plan period, the CPC Central Committee and the State Council made strategic decisions to promote the construction of livable, productive, and harmonious rural areas, strengthen the governance of agricultural non-point source pollution, advance carbon emission reduction and carbon sequestration in agriculture and rural areas, and improve the rural ecological environment, to ensure that a healthy ecosystem underpins rural revitalization. Rural domestic waste management constitutes an integral part of these efforts. Drawing on policy implementation and practical progress in rural domestic waste management during this period, this paper systematically analyzed the regional characteristics and current status of technological application in waste management. The findings indicated that during the 14th Five-Year Plan period, China intensified rural domestic waste management, steadily improved policy and standardization frameworks, gradually upgraded the collection, transport, and disposal system (CTDS), and elevated overall governance capacity. By the end of 2025, the proportion of administrative villages with waste collection and transport services had remained stable above 90%; over 95% of administrative villages had conducted rural sanitation campaigns; and more than 18% had implemented fee systems. Nevertheless, China’s rural domestic waste governance still remains in a phase characterized by the issues of addressing “universal coverage” and “quality enhancement”coexist. It faces persistent bottlenecks, including sluggish progress in source separation and waste reduction as well as resource recovery, marked deficiencies in collection, transportation and disposal infrastructure in remote areas, inadequate operational and management capacity, and unsustainable financing mechanisms. To address these core challenges, this paper proposes targeted policy recommendations centering on optimizing the governance layout, deepening source separation and waste reduction with resource recovery, strengthening long-term operation and supervision mechanisms, and improving diversified funding guarantee systems, all with a view to inform the high-quality development of rural domestic waste management during the upcoming 15th Five-Year Plan period.

In this study, the three-stage countercurrent water-washing products of municipal solid waste incineration (MSWI) fly ash were taken as the research objects. Leaching tests were conducted respectively in accordance with three standard methods: HJ 557—2010 Solid Waste Extraction Procedure for Leaching Toxicity Horizontal Vibration Method, HJ/T 299—2007 Solid Waste Extraction Procedure for Leaching Toxicity Sulphuric Acid and Nitric Acid Method, and HJ/T 300—2007 Solid Waste Extraction Procedure for Leaching Toxicity Acetic Acid Buffer Solution Method. The leaching toxicity characteristics of heavy metals in water-washed fly ash under different leaching systems were compared and analyzed, and a simplified overall pollution toxicity index (OPTIs) was introduced to evaluate the environmental risks. The results indicated that the leaching efficiencies of Cu, Zn, Mn, Cd, Pb, and Ni under the acetic acid buffer solution method were significantly higher than those under the other two methods, with concentrations generally 1-2 orders of magnitude higher. Specifically, under the acetic acid method, the average leaching concentrations of Zn and Cd reached 14.00 mg/L and 1.23 mg/L, respectively, exceeding the grade I limits of GB 8978—1996 Integrated Wastewater Discharge Standard by 6.0 and 11.3 times, respectively. In contrast, the concentrations detected via the horizontal vibration and sulfuric-nitric acid methods remained below the regulatory limits. The comprehensive toxicity evaluation identified Cd and Zn as the primary contributors to the leaching toxicity of washed fly ash, driven by the high ecological risk potential of Cd and the high leaching concentration of Zn. Although the current technical specification HJ 1134—2020 Technical Specification for Pollution Control of Fly-ash from Municipal Solid Waste Incineration (for trial implementation) primarily relies on the horizontal vibration method for toxicity evaluation, washed fly ash still poses a risk of heavy metal migration under specific acidic scenarios. Therefore, it is recommended to incorporate the acetic acid buffer solution method as a supplementary evaluation for extreme acidic scenarios in the environmental risk assessment of resource utilization of water-washed fly ash，and to establish a tiered assessment framework, providing a more robust scientific basis for the safe utilization of MSWI fly ash.