The environmental risk of groundwater in landfills has become increasingly prominent, which requires targeted control and remediation strategies. In this study, a landfill site in South China was taken as an example. According to the zoning collaborative control and repair of pollution source control area, groundwater treatment area and groundwater prevention and control area, the control strategy of pollution source reduction, leakage path obstruction, groundwater remediation and monitoring natural attenuation was proposed. The results showed that after six months operation of the leachate drainage system, the liquid level in front of the dam decreased by 3.2-3.4 m, effectively reducing the pollution source. After grouting the dam abutment, the permeability coefficient decreased to 8.10×10-7-8.91×10-6 cm/s, blocking the diffusion pathway of leachate. After three months operation of the groundwater extraction treatment system, the removal rates of ammonia nitrogen and chemical oxygen demand downstream of the waste dam were 77.3%-82.0% and 75.8%-78.1%, respectively. After the completion of groundwater extraction treatment, the groundwater circulation well system operated for three months, and the removal efficiency of ammonia nitrogen and chemical oxygen demand increased by 10.4-16.8 percentage points and 9.5-12.5 percentage points, respectively. Through hydraulic control and natural attenuation monitoring, the pollution plume has been effectively intercepted and the pollutant concentration continuing to decline.

To address leachate accumulation caused by the increasing landfill volumes, a domestic waste sanitary landfill in Liaoning province expanded and upgraded its leachate treatment facilities, adding a treatment capacity of 600 m3/d. The leachate treatment adopted a process of “equalization + membrane bioreactor (MBR) + nanofiltration + reverse osmosis”. Nanofiltration concentrate was treated using a “volume reduction + coagulation-sedimentation” process, while reverse osmosis concentrate was treated by the process of “low-temperature evaporation+drying”, thereby achieving full-volume treatment. The design effluent standard complies with the class 1A limits specified in GB 18918—2002 Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant. Operational results showed that the system performed stably, with effluent COD content<20 mg/L, NH3-N content≤5 mg/L, and TN content≤10 mg/L, consistently meeting and outperforming the discharge limits. By adopting low-energy-consumption blowers and taking advantages of the low-temperature evaporation (LTE) process, the project effectively controlled operating costs, with a unit treatment cost of approximately 125 yuan/m3. This project provides a mature technical model for the efficient and cost-effective treatment of leachate at aging landfills, achieving a synergistic improvement in both treatment efficiency and economic performance.

To mitigate the environmental odorous and safety risks during the excavation of aged municipal solid waste (MSW) in landfills, and to address the long processing duration drawback of conventional aerobic stabilization technologies,the aged MSW with a landfill age of approximately 5 to 10 years from a large-scale MSW landfill in South China was taken as the research sample, and a small-scale laboratory device for rapid aerobic environment simulation was constructed. Using reaction tanks with air flow rates of 15 L/min and 10 L/min, and the AERMOD atmospheric dispersion model was applied for simulation analysis to systematically investigate the variation laws and diffusion behaviors of malodorous pollutants during the rapid aerobic stabilization process. The results indicated that based on on-site monitoring data of the landfill, ammonia was identified as the representative pollutant for rapid aerobic pretreatment. The ammonia concentration exhibited a variation trend of “rapid decline in the initial phase, stabilization in the later phase, and rebound after shutdown”, which was attributed to the stage-specific degradation effect of aerobic treatment on NH3. AERMOD model simulation results showed that the post-attenuation ratios of ammonia at distances of 10 m, 100 m, and 300 m along the dominant diffusion direction were 93%, 23%, and 6%, respectively, with the attenuation rate slowing significantly as the distance increased. The solubility of ammonia was much higher than that of other malodorous pollutants, making it prone to migrate with moisture and expand the pollution scope. Based on these findings, it was recommended to prioritize an aeration rate of 15 L/min or higher, maintain intermittent aeration for a minimum of 1 344 hours, enhance ventilation in the initial phase and supplementary deodorization measures in the later phase and install drying devices during aeration. These measures could effectively improve the aerobic stabilization efficiency of the pretreatment process prior to aged waste excavation in the landfill and further mitigate the diffusion of odorous pollutants.

The scientific validity and rationality of soil eco-environmental baselines for informal solid waste landfills fundamentally govern the impartiality of assessment conclusions and the efficacy of remediation strategies. To address the prevalent issue whereby national risk screening values are routinely substituted for regional environmental baselines in current soil ecological damage assessments， practices that readily generate false positives in high-background areas and false negatives in low-background areas， this study investigated nine typical informal solid waste landfills in the Yangtze River Delta. Stratified soil samples were collected at depths of 0-0.5 m and 0.5-5.0 m, with two reference frameworks employed: the control-area baseline derived from on-site survey statistics, and the standard baseline represented by national risk screening values. A systematic comparison was conducted to elucidate discrepancies between these two baselines regarding pollution identification, exceedance determination, and remediation depth accounting. The results showed that the control area baseline was generally 24.2% to 99.8% lower than the standard baseline, exhibiting significant gradients with soil depth and pollutant type. When assessed against the control area baseline, the overall exceedance rate increased from 10.8% to 47.3%, revealing substantial “hidden” pollution that met regulatory standards but exceeded local baseline levels. Domestic waste landfills exhibited characteristics of “low-concentration, large-scale” non-point source accumulation, while industrial waste landfills showed “composite-deep” penetration patterns. Embedding the “real regional background” as living data that can be cited on demand will defuse the risks of “false compliance”, “excessive compensation” and “over-remediation”, promoting soil ecological environment damage assessment for informal landfills from “one-size-fits-all national line” to “true local baseline” and providing closed-loop support for precise identification, moderate remediation and fair compensation.

Municipal solid waste incineration (MSWI) bottom ash represents a promising precursor for alkali-activated cementitious materials, owing to its abundant supply and high content of reactive Si, Ca, and Al. However, effective pretreatment is mandatory to manage its inherent heavy metals and soluble salts. The hydration mechanism of this type of cementitious material is a process dominated by an alkaline environment. The hydration degree is synergistically tunable by the ash fineness, alkali activator type, and supplementary cementitious materials. Research demonstrates that optimizing the ratio of activators to composite systems can enhance mechanical performance, while suitable pretreatment improves durability against freeze-thaw and sulfate attack. The alkali-activated system also ensures environmental safety by efficient immobilizing heavy metals via gel-based physical encapsulation and chemical bonding. Rational matching of the activator system, the bottom ash characteristics and the auxiliary cementitious materials is pivotal for tailoring the setting time to ensure the success of its practical application. However, key research bottlenecks still persist, particularly concerning the synergistic mechanisms of composite activators, detailed reaction pathways and microstructural evolution remain unclear, alongside a lack of systematic investigation into long-term durability of materials and their performance evolution under real service conditions.

To achieve nutrients recovery from source-separated urine, the study investigated the impact of key factors in a vacuum membrane distillation system on the concentration effect and energy consumption of alkalized urine. Real fresh urine, alkalized and diluted fivefold with calcium hydroxide, was used as the treatment object. The influence of feed temperature (40-70 ℃), condensation temperature (0-20 ℃), and feed pump speed (1 000-1 600 r/min) was investigated, and the significance of each factor was analyzed through multiple linear regression. The results showed that feed temperature was the core factor affecting membrane flux and energy consumption. When the temperature increased from 40 ℃ to 70 ℃, membrane flux increased from 0.82 L/(m2·h)to 3.02 L/(m2·h). When the feed temperature was 70 ℃, the water recovery efficiency reached 72.36%, the urine concentration index reached 3.62, and the specific energy consumption decreased by 29.3%. At a condensation temperature of 20 ℃, membrane flux, water recovery efficiency, and energy consumption efficiency were all superior to those at 0 ℃, with a specific energy consumption reduction of 13.0%. The feed pump speed had no significant impact on treatment efficiency and energy consumption, with membrane flux stabilizing at 1.99-2.06 L/(m2·h)and specific energy consumption maintaining at 1.429-1.442 kWh/L. The total energy consumption of the system mainly came from the heating of the feed, with a total salt rejection efficiency exceeding 98.5% and a total nitrogen recovery efficiency of over 80%. The multiple linear regression model exhibited good fit with the experimental results. This study indicates that vacuum membrane distillation is suitable for the concentration of alkalized urine, providing theoretical support for process optimization.

Aiming at the problem of delayed CO concentration measurement in the grate furnace system of domestic waste incineration, the correlation between the continuous images of high-temperature flue gas and the CO concentration level at the first flue of the domestic waste incineration grate furnace was studied, and a real-time monitoring method for the CO concentration level at the first flue based on a three-dimensional convolutional neural network model was proposed. Firstly, a large number of high-temperature flue gas images in the furnace and CO concentration data in the flue were obtained by high-temperature industrial cameras and high-temperature laser flue gas analyzers TDLAS to produce a “high-temperature flue gas image sequence-CO concentration level” dataset. Secondly, the data set was used to train a CO concentration level classification model based on the Slow-Fast three-dimensional convolutional neural network model. The classification accuracy of this classification model on the validation set can reach 95.40%, which is about 7.8 percentage points higher than that of the traditional single-frame image classification algorithm, and the classification result is highly stable, which better meets the actual needs of the project. Finally, the fine-tuned CO concentration level classification model was deployed on a domestic waste incineration grate furnace system, and the online effect evaluation was carried out. The model performed inference once per second. Compared with the results of high-temperature laser flue gas analyzer TDLAS and continuous flue gas emission monitoring system CEMS, it was found that the recall rate and alarm accuracy of the model reached 90.7% and 68.5% respectively, and the model achieved an early warning of about 214 seconds for all CO exceeding the standard conditions in CEMS. The comparison results proved that the proposed method had high application value and prospects in improving the environmental protection performance of municipal solid waste incinerator operation.

For terminal control of PCDD/Fs generated during municipal solid waste (MSW) incineration, the predominant technology employs adsorption by activated carbon powder, combined with filtration and collection via fabric bag filters. This process concentrates PCDD/Fs into fly ash, although the total quantity remains unchanged. In this research, a dry process with deacidification+catalytic ceramic fiber tube integrated system+heat exchange+activated carbon fixed-bed adsorber was utilized. We deployed a pilot-scale system in a waste-to-energy plant, conducting sample collection at multiple locations and analyzing dioxin emission levels, and the mechanisms of dioxin formation and control were investigated. The results showed that the initial dioxin concentration (measured in TEQ) in the flue gas from the circulating fluidized bed (CFB) economizer section was 29.840 ng/m3, with the solid phase accounting for 80.46%. Using a hybrid system of catalytic ceramic fiber tubes coupled with an activated carbon fixed-bed adsorber, PCDD/Fs removal rate of 99.93% was achieved, resulting in a final emission concentration (measured in TEQ) of 0.022 ng/m3. The catalytic ceramic fiber tubes can physically intercept and filter solid-phase PCDD/Fs, and chemically decompose gaseous-phase PCDD/Fs, leading to an overall reduction in total dioxin levels. This study provides theoretical reference for dioxin control in MSW incineration flue gas.

The selective non-catalytic reduction (SNCR) denitrification system of the municipal solid waste incineration plant mainly relies on the preset static mapping table of NOx concentration and ammonia injection amount at the outlet of the bag filter, which adjusts the ammonia injection amount by real-time detection of parameters such as flue gas temperature and flow rate and checking the table. Due to the lack of adaptability to the dynamic characteristics of the operating conditions, the control stability is poor. Based on it, an efficient composite control method for the SNCR denitrification system in domestic waste incineration plants is proposed. The K-means algorithm is used to iteratively update the clustering centers to cluster the typical operating conditions of the SNCR denitrification system. Based on the clustering results of typical operating conditions, the operating condition dataset is divided. The training process of the model is divided into initialization stage and online learning stage using an online sequential extreme learning machine (OS-ELM). The model parameters are adjusted to adapt to the dynamic characteristics of the denitrification system by combining real-time operating data of the denitrification system, and the NOx concentration at the outlet of the bag filter is predicted. Using NOx concentration and real-time flue gas parameters as state inputs, and ammonia injection amount adjustment as action space, a reinforcement learning algorithm based Actor network is used to generate ammonia injection strategy, and the intelligent agent dynamically optimizes ammonia injection control through online interactive learning. Further more, the control stability of the proposed method has been tested. The final test results show that when using the proposed method for composite control, the fluctuation rate of ammonia injection amount is 4.2%, which has a relatively ideal control effect.

Waste incineration fly ash, as a hazardous waste containing heavy metals and dioxins, has become a critical bottleneck constraining the waste-to-energy industry. High-temperature melting can transform fly ash into a dense glassy material, offering pathways for both volume reduction and resource recovery. In response to the challenges of significant fluctuations in fly ash composition and poor vitreous quality, a process route for preparing microcrystalline glass through plasma high-temperature melting was proposed, which regulated the composition ratio of the calcium-aluminum-silicon three-phase system in fly ash based on thermodynamic equilibrium calculations. Theoretical calculations revealed that at 1 450 ℃, the single-liquid-phase region of the calcium-aluminum-silicon system (CaO-Al2O3-SiO2) were CaO 5%-60%, Al2O3 5%-55%, and SiO2 25%-75%. Based on this, 14 different formulations（P1-P14）were developed using fly ash and coal fly ash, through experimental and characterization studies validated the glass formation efficacy. Results showed that the complete melting temperatures(1 293-1 338 ℃) of the formulations (P3, P5, P6, P9) within the single-phase region were relatively low. Calculated data for liquid phases and molten salts suggested that formulations within the single liquid phase region were more readily capable of achieving overall liquid phase transformation and vitrification at the target melting temperature of 1 450 ℃. Formulations within the single liquid phase region appeared a green, smooth, and uniform glass matrix after melting at an equipment current of 120 A (approximately 1 450 ℃). XRD results revealed that the melted product primarily exhibited diffuse peaks characteristic of the glass phase, overlaid with weak crystalline peaks such as SiO2. The elements were predominantly oxygen, silicon, calcium, aluminum and distributed uniformly. In contrast, formulations with a single liquid phase region (P1, P7) exhibited higher complete melting temperatures (1 600 ℃, 1 595 ℃). Both computational and characterization results indicated that these formulations were unfavorable for forming stable vitrified products at the target temperature. In summary, formulation adjustments based on single liquid phase regions provided a basis for thermodynamic control and stable vitrification in the fly ash melting process.

With the continuous expansion of the scale of municipal solid waste incineration, the generation of incineration fly ash has significantly increased, and its resource utilization has become a research hotspot. A systematic review was conducted on the research progress of using fly ash from domestic waste incineration as an alternative to inorganic cementitious materials. The fly ash contains active components such as CaO, SiO2, and Al2O3, and has potential for cementation. However, due to the presence of a large amount of pollutants such as chlorides, heavy metals and dioxins, its direct utilization is restricted. Studies show that through pre-treatment methods such as water washing, heat treatment, and carbonation, harmful components in fly ash can be effectively removed or stabilized, thereby improving its physical and chemical properties. The treated fly ash can be used to prepare building materials such as concrete, roadbed materials and geopolymer products by replacing cement at an appropriate blending ratio of no more than 30%. The leaching concentration of heavy metals is lower than the national standard limit, ensuring good environmental safety. Future research should focus on developing efficient and low-consumption composite pretreatment technologies, strengthening long-term performance and environmental risk assessment, and establishing a standardized application system, in order to promote the scale-up and high-value utilization of fly ash in building materials.

ased on a sewage treatment plant in Ningbo with a processing capacity of 1.0×105 m3/d, this study evaluated the technical feasibility and economic benefits of using the oxidation liquid produced from the wet oxidation of kitchen waste as an additional carbon source through engineering practice. The experiment was conducted in stages, gradually increasing the dosage of the oxidation liquid from 10 m3/d to 30 m3/d, replacing part of the sodium acetate added to the denitrification tank of the A/O system, to investigate its impact on the system treatment effect and the carbon sources cost. Results showed that effluent COD and TN consistently met discharge standards before and after dosing oxidation liquid, with no increased risk of pollutant release. When the oxidation liquid dosage reached to 30 m3/d, the COD removal rate increased by approximately 3.63 percentage points compared to the period without oxidation liquid. TN removal also improved during all dosing phases. Economic analysis revealed that the cost of carbon source saved by adding oxidation liquid during the actual operation period in 2024 was 127.88 yuan per cubic meter. This study provided a practical technical pathway for the resource utilization of organic waste and the cost reduction and efficiency improvement of wastewater treatment plants.

For the anaerobic biogas slurry, and other industrial and domestic wastewater produced from a food waste treatment plant in Zhejiang, the “regulating tank + air flotation + MBR built-in membrane + nanofiltration system” process was adopted, and the main indicators of effluent complied with the third-level standards of GB 8978—1996 Integrated Wastewater Discharge Standard. Through a series of process design optimization measures such as strengthening pretreatment to remove oil and impurities, extending biochemical retention time, and increasing reflux multiples, the treatment effects of relevant operation data during debugging were analyzed. Under pre-treatment settings with multi-precision interception of solids, a total hydraulic retention time in the bioreactor of 16.17 days, and a 48-fold recirculation rate, the removal rates of CODCr, ammonia nitrogen, and total nitrogen by membrane bioreactor were not less than (96.15±1.75)%, (99.64±0.17)%, and (97.14±0.59)%, respectively, and the effluent from MBR ultrafiltration could stably meet the standards. The system demonstrates excellent treatment performance, operates with high energy efficiency and low carbon emissions, and possesses strong economic viability and broad application potential.

To elucidate the intrinsic driving mechanisms and reveal the dynamic evolution of residents’ willingness to participate in waste separation, Shanghai was taken as a case. By integrating longitudinal tracking with dynamic simulation, it employed targeted questionnaire surveys, Geodetector method, and system dynamics modeling to identify key influencing factors and their interaction effects, as well as to simulate the improvement effectiveness of different intervention measures. Results showed that one year after classification policy implementation, residents’ satisfaction increased by 2.7%, whereas their willingness to participate decreased by 5.4%. The key influencing factors of participation willingness exhibited temporal heterogeneity. Before the implementation of the classification policy, factors such as classification attitude, public publicity, classification recycling methods, classification time consumption and classification refinement were the main influencing factors. After the policy implementation, the community waste collection satisfaction of the impact factors soared and showed a significant interaction effect with classification recycling methods. Policy simulation reveals that refined waste separation exerts a negative effect on residents’ willingness to participate. However, improving community norms and facility convenience produces positive compensatory effects. The research is aimed at revealing the impact of institutional changes on residents’ willingness to participate, and optimizing policy intervention measures.

In 2021, Zhongshan city completed the organic waste resource utilization project and comprehensively promoted the resource utilization of food waste. At present, Zhongshan city has established a collection and transportation system for food waste. By the first half of 2025, the daily average collection and transportation volume reached the scale of food waste treatment. However, there were still problems such as untimely and inadequate collection and transportation, and non-standard operations, which affect the efficiency of food waste resource utilization. Based on the existing food waste collection and transportation system in urban areas of Zhongshan city, this paper studied and analyzed the existing problems. Referring to the main urban food waste collection and transportation models and experience practices in China, countermeasures and suggestions for improving food waste collection and transportation system in urban areas have been proposed to help enhance the quality of food waste collection and transportation services and the resource utilization rate throughout the city.