Direct air-cooled condenser(DACC) system poses great advantage on water-saving compared to wet cooling system. However, lower efficiency and higher initial investment remain critical bottleneck issues that need to be addressed. A scale of 2×750 t/d municipal solid waste incineration (MSWI) power plant with 45 MW turbine and generator unit in Central Asia was taken as an example, combined with thermal calculation, off-design conditions operation, and the maximum annual net power generation profit and profit of the whole life cycle method, initial temperature difference(ITD, namely the difference between the condensate temperature corresponding to exhaust pressure of the turbine and the design environment temperature) optimization, main design parameters selection and optimization method for DACC of waste incineration power plants were formed, in order to achieve the dual goals of harmless treatment of waste incineration and increase the net profit of the whole life cycle of waste incineration. Optimal ITD value of this project was obtained as 18.97 ℃ (design ambient temperature 35 ℃ and exhaust pressure 15 kPa), face velocity was 2.00-2.25 m/s and heat transfer area was approximately 3.15×105 m2. The research results showed that the increase rate of heat transfer area was sharply varied with the design ambient temperature and exhaust pressure when the design ambient temperature was higher than a certain value. And it also revealed that electricity sales price was one of the important factors of ITD and when it was at a higher level, it could increase the heat transfer area of condenser (that is, by choosing a smaller ITD value) to get maximum annual net profit and net profit of whole lifecycle. And the ITD value increased with the rise of the bundle price which was a significant ITD sensitive factor. Face velocity had a great influence on the heat transfer area and power consumption of fans and there was an optimal face velocity(2.00-2.25 m/s) to achieve maximum annual net profit. Compared with thermal power plants, ITD of MSWI plants was lower, and the design ambient temperature should be determined more closely in combination with typical annual meteorological parameters through ITD optimization and the design ambient temperature method for DACC recommended in DL/T 5339—2018 Code for Hydraulic Design of Fossil Fired Power Plant .

The circulating water pump is a core power-consuming device in the cold-end system of waste-to-energy incineration plants, while its operational efficiency and system compatibility directly impact the plant’s electricity consumption rate, unit vacuum level, and overall economic performance. Taking the waste-to-energy incineration plant (600 t/d grate furnace + 15 MW unit) in Yuanyang county, Xinxiang city, Henan province as a case study, this paper addresses issues such as cavitation, excessive vibration, high noise, and inefficiency in the actual operation of circulating water pumps caused by severe deviations from design operating conditions (particularly during single-pump operation, the reduces of pipeline system resistance results in actual flow rates far exceeding the design-rated flow, leading to inefficient pump operation). Comprehensive energy-saving measures have been implemented, including replacing circulating water pumps with models matching flow and head requirements during single-pump operation, and adopting a combination of high-power frequency pumps and variable-frequency small pumps during dual-pump operation. After optimization, the circulating water system can save 5.25×105 kWh of electricity throughout the year, equivalent to an annual carbon emission reduction (calculated as CO2) of 299.41 t, with an overall energy-saving rate of 39%.

This study focused on the Luzhuangzi site in the decommissioned Tiangang Liulin Industrial Agglomeration Zone in Tianjin. To address the challenges of chlorinated hydrocarbon contamination characterized by complex sources, high mobility, and remediation difficulties, the research carried out engineering practices of contamination tracing, spatial distribution characterization, and low-carbon remediation. The contaminated soil area of the site was 5 099.8 m2, with a contaminated earthwork volume of 39 236.7 m3. The contaminated groundwater area was 21 079.9 m2, with a contaminated aquifer thickness of 14.3 m. The characteristic contaminants of the site were tetrachloroethylene, trichloroethylene, vinyl chloride, cis-1,2-dichloroethylene, ethylbenzene, and petroleum hydrocarbons. Geological conductivity imaging technology was employed to accurately identify the contamination spatial distribution. A zoning-classification-grading remediation strategy was developed based on contamination levels and hydrogeological conditions, and bench-scale experiments were conducted to determine grading benchmarks and remediation technologies. A combined remediation approach of targeted source removal, contamination reduction, comprehensive restoration was implemented, incorporating in situ chemical oxidation, thermally enhanced soil vapor extraction, cement kiln co-processing, and groundwater pump-and-treat. The results demonstrated that the combined process achieved efficient contaminant removal while reducing carbon emissions by 41% compared to single-technology approaches, achieved green remediation of contaminated land. This study provides a technical reference and engineering demonstration for the precise and low-carbon remediation of similar industrial legacy sites.

The determination of soil baseline values is a critical step in the identification and assessment of ecological environmental damage, as its accuracy directly influences the attribution of pollution responsibility and the outcomes of ecological environmental damage assessments. Guided by GB/T 39791.4—2024 Technical Guidelines for Identification and Assessment of Environmental Damage: General Principles and Key Procedures: Part 4: Investigation and Determination of Soil Environmental Baseline, this study systematically investigated the distribution test of soil background data and the determination of baseline values, using measured soil data from a specific area in northwestern Shanghai as a case study. Through statistical analysis of 14 indicators, including pH, organic matter, and heavy metals, across different soil depths（surface, shallow, and deep layers）, and by comprehensively applying methods such as the Shapiro-Wilk test, graphical methods（histograms, Q-Q plots, P-P plots）, and Dixon outlier test, the data distribution types for each indicator were clarified, and corresponding baseline values for the soil ecological environment were calculated. The results indicated that indicators such as As and Zn exhibited non-normal distributions in the surface layer, reflecting characteristics of exogenous pollution input. The non-normal distributions of Cd and Hg in the shallow layer suggested potential vertical migration and enrichment behaviors of pollutants. Most indicators in the deep soil layers showed normal distributions, representing the natural background levels. This study also found that for pH, the median was more appropriate than the upper limit of the standard-recommended reference value as the baseline to avoid misjudgment. The findings provide a scientific basis for the identification of ecological environmental damage in urban construction waste and other contaminated sites, highlighting the importance of site-specific baselines， and offering optimization suggestions for the practical application of GB/T 39791.4—2024.

The remediation of agricultural and mountain soils contaminated by atmospheric deposition of heavy metals has emerged as a new research hotspot, following the remediation of typical industrially polluted sites. Such contaminated areas are usually extensive, involving large volumes of soil with generally lower contamination levels compared to factory zones in industrial areas. To evaluate the applicability and cost-effectiveness of the leaching remediation technology in the treatment of such pollution, the representative atmospheric-heavy metal-polluted agricultural and mountain soils were selected from the vicinity of an industrial area in Zhuzhou city, Hunan province. The particle-size fractionation leaching experiments were conducted, soils were separated into fine (<0.074 mm), medium (0.074-0.250 mm), and coarse (>0.250 mm) fractions. Results showed that fine particles accounted for more than 60% of agricultural soils, and heavy metal concentrations increased with the increase of particle size. The concentration of heavy metals in sandy mountain soils was also related to particle size. Particle-size-specific leaching could reduce polluted agricultural soils by 78%-82% and by more than 31% in mountain soils. These findings provided a technical reference for the large-scale remediation of soils contaminated by atmospheric deposition of heavy metals.

According to the problems of landfill leachate aging and difficult treatment after closure, the scattered pressure filtrate from the transfer station was collected and transported to the landfill for synergistic treatment by using its characteristics of high COD and low ammonia nitrogen. Taking the leachate from transfer station combined with landfill leachate in a city of Jiangsu as an example, the landfill leachate production after the closure was 250 m3/d, the pressure filtrate production from the transfer station was 100 m3/d, and the processing scale of current landfill leachate treatment station was 600 m3/d. The main treatment process is pretreatment + external MBR + NF + RO. NF and RO concentrate are evaporated after reduction, and the equipment and facilities of the existing landfill leachate are calculated according to the water quality and quantity of the mixture. According to the calculation, the existing buildings and equipment only need to be partially opened, and the rest can be used as standby or part of the equipment to reduce the daily operation time to meet the treatment of the mixed liquid and meet the standard. According to the calculation, the operating cost of the leachate co-processing section of “pretreatment + external MBR + NF + RO + concentrate reduction” is 93.53 yuan/m3, the operation cost of the evaporation section of the concentrated liquid is 365.27 yuan/m3. Compared with the decentralized treatment process, the synergistic treatment process can save the cost of 1.967 4 million yuan per year. The overall operation of the collaborative treatment system is good, and the effluent quality is stable and up to standard, which achieves the goal of intensive layout and energy saving.

Hydrogen sulfide (H2S) is a key odorous pollutant in solid waste treatment facilities, often leading to odor nuisance and environmental complaints. Therefore, accurate prediction of H2S is essential for odor pollution risk prevention and control. Based on hourly monitoring data of H2S concentrations collected from three stations at a solid waste treatment site in Shanghai from 2018 to 2021, this study proposed a hybrid model combining Empirical Mode Decomposition (EMD) and Long Short-Term Memory (LSTM) networks, namely the EMD-LSTM model, for predicting H2S concentrations at the base. The analysis showed that while the average temperatures at the three sites were similar, wind speeds differed significantly. H2S concentrations fluctuated considerably across all sites, with the southern boundary site, adjacent to the municipal solid waste landfill operation area, exhibiting significantly higher H2S concentrations than the other sites. Using wind speed, wind direction, temperature, humidity, air pressure, and ammonia concentration as input features, the EMD-LSTM model achieved accurate prediction of H2S concentrations. The prediction results demonstrated that the model performed well in forecasting concentrations for the next hour, with acceptable levels of mean absolute error (MAE: 1.71-13.13 μg/m3) and coefficient of determination (R2： 0.74-0.84) across the three boundary sites. The model performed best at the northern boundary site, where emissions were relatively stable (MAE: 1.71 μg/m3). The results verify the effectiveness and generalization capability of the model, providing technical support for precise early warning of odor pollution and emergency management decision-making at solid waste disposal bases.

Based on 52 typical application cases from both domestic and international sources over the past 25 years, the differential landscape, core bottlenecks, and underlying causes in the market promotion of domestic waste pneumatic conveying system in both domestic and international were systematically analyzed. It further focused on exploring the development path of this system under the backdrop of the “dual carbon” goals and the construction of “zero-waste cities”, which realized the marketization of environmental protection value through energy structure transformation and model innovation. Analysis indicated that high initial investment, monopolies on foreign technology, technical challenges such as pipeline clogging and abrasion, and an underdeveloped specialized operation and maintenance system were the main bottlenecks hindering the large-scale adoption of this system in China. The study further revealed that the carbon footprint of the system was highly dependent on the electricity structure during the operation phase, and its life cycle environmental impact varied with the increasing cleanliness level of the power grid. The conclusion pointed out that by promoting urban planning integration, green power coupling, innovative carbon accounting methodologies, and smart operation and maintenance, the environmental benefits of the system could be effectively translated into economic value, which would help overcome barriers to market-oriented promotion, enable it to become an important technological option for supporting the construction of “zero-waste cities” and achieving the “dual carbon” goals.

Taking the municipal solid waste containerized inland waterway transport system in Shanghai as an example, the technical upgrade for the vertical baler system at a transfer station was carried out. The original station utilized a horizontal compression process, which was converted to a vertical compression system in 2017 to meet waste classification requirements. The modified baler system initially experienced severe waste scattering and container leakage during operation. By optimizing the chute structure, enhancing sealing performance, and improving the loading and compression process, the issue of waste scattering was effectively resolved, leading to a significant improvement in the on-site working environment. Post-improvement operational data indicated that the score for the degree of waste scattering on the first-floor ground had reduced by 75%, the score for carry-over and leakage from dry waste containers had decreased by 82%, and the kitchen waste containers had achieved zero carry-over and zero leakage. Additionally, the operating costs for the equipment at a single set of the loading berths have been reduced by 56%. These outcomes demonstrated a dual enhancement in both environmental benefit and economic benefit, providing a practical reference for the technical transformation of similar transfer stations.

To address the challenge of carbon emission reduction in putrescible waste treatment during urbanization, this study conducted Life Cycle Assessment (LCA) of three typical putrescible waste treatment plants in Hangzhou to quantify carbon emissions and comprehensive environmental impacts across the entire chain (pretreatment-anaerobic digestion-wastewater treatment). The results indicated that the carbon emissions per 1.00×104 t of putrescible waste treated ranged from -82.83 t to 150.29 t (in terms of carbon dioxide equivalent). Grid electricity consumption and wastewater discharge were identified as the main sources of carbon emissions, with grid electricity (primarily coal-based) contributing over 58% of the system’s total. The use of hydrochloric acid and methanol were the primary contributors to carbon emissions from wastewater discharge, with hydrochloric acid accounting for approximately 65% of the carbon emissions in the wastewater treatment stage at Plant A, and methanol contributing above 75% at Plant B. Grid-connected electricity from biogas power generation could offset 9% to 220% of carbon emissions, highlighting energy recovery efficiency was a crucial pathway for emission reduction. For the three plants, the main environmental risks were human carcinogenic toxicity, freshwater ecotoxicity, and marine ecotoxicity. The primary source of these risks was wastewater treatment for Plant A, and gutter oil treatment for Plant B. Grid electricity consumption was a notable contributor to the environmental impact across all three plants.

Based on the first-phase project of a wet waste treatment plant in Shanghai, aiming at the problems of insufficient reduction and resource utilization rates in wet waste treatment, experimental research on the organic solid residue recirculation prehydrolysis technology was carried out. A process channel of “biological leaching hydrolysis-squeeze solid and liquid separation-three phase separation extraction-reflux hydrolysis” was constructed to explore its optimization effects. Based on the component characteristic analysis of wet waste, mixed residues, organic solid residues, and digestate, the optimization effects were verified through on-site experiments. The results showed that the recirculation prehydrolysis technology could effectively reduce the overall plant residue discharge rate by more than 5%, while increase the COD concentration in the anaerobic system, and raise the biogas production rate per ton of waste by more than 10 m3/t. The data from the second-phase of the project were used to verify the technology’s role in improving the organic matter conversion rate and resource utilization level. In view of the limitations of the temporary process channel for the field experiment of recirculation prehydrolysis, a technical renovation plan for the original first-phase process route was proposed. The economic analysis of the proposed technical renovation plan showed that the annual comprehensive economic benefit after the retrofit could reach 2.221 3 million yuan, which mainly from the reduction of residue disposal costs and the increase in biogas power generation revenue. The study aims to optimize wet waste treatment processes, enhance the levels of waste reduction and resource recovery, and provide a feasible solution for the technical optimization and economic benefit improvement of similar projects.

In response to the strict demands for high reliability and equipment compactness of the quench heat exchanger of flue gas from the high-temperature pyrolysis incineration of medical waste, this research innovatively designed a vertical multi-pass quench heat exchanger, with flue gas flowing through the tube side and cooling water through the shell side. Taking the inlet and outlet temperatures on the flue gas side and the working medium side, as well as the system pressure drop as the core evaluation indicators, numerical simulation and multi-objective optimization of the heat exchanger were conducted with SolidWorks Flow Simulation. The research has determined the optimal design scheme (single arched baffle plate, with the inlet and outlet on the same side) for the prototype that achieves the best overall performance under the premise of meeting the quenching process requirements. Prototype testing results demonstrated that the heat exchanger achieved effective quenching performance with reasonable flow resistance, and could achieve ash cleaning. It was well-suited for integration requirements of the vehicle-mounted treatment systems, providing important support for the key technological breakthroughs of the small-scale, mobile skid-mounted high-temperature pyrolysis incineration complete equipment for medical waste.

The development of strategic emerging industries, centered on new productive forces, is crucial for promoting high-quality economic growth. However, the associated generation of new types of hazardous waste poses severe challenges to urban environmental management. Taking Shanghai as a case study, Material Flow Analysis (MFA) was employed to systematically investigate the current state of hazardous waste management in five major emerging industries: integrated circuits, biomedicine, new materials, and others. By collecting 2024 hazardous waste data from 211 key enterprises and establishing core indicators such as recycling utilization rate and external transfer rate, the generation characteristics, flow paths, and disposal bottlenecks of waste at both the municipal and industrial levels were deeply analyzed. The research revealed that emerging industries have become the primary source of hazardous waste in Shanghai. Among them, the new materials and integrated circuit sectors exhibit the highest waste generation intensity. HW06 (waste organic solvents and waste containing organic solvents), HW11 (distillation residues), and HW34 (waste acids) are the three largest categories by volume, possessing significant recycling potential yet remaining underutilized. Furthermore, local disposal capacity suffers from structural deficiencies, leading to a strong reliance on regional collaborative disposal. Accordingly, this paper proposes that strategies should be adopted from the perspectives of implementing industry-specific precision management (“one-policy-per-industry”), overcoming technical bottlenecks in the recycling of core waste streams, and optimizing the layout of local disposal facilities. These measures aim to address the complex situation of hazardous waste management in emerging industries and promote the synergistic development of Shanghai’s economy and environmental protection.

Many cities in China are now introducing carbon inclusive mechanism methodologies related to waste classification, but the incentive objects vary across regions. In response to the demand for allocation of carbon emission reduction credits based on different links of the whole-process waste classification, a monetized calculation method was proposed, calculating the proportion of carbon emission reduction contribution for each link based on the incremental investment in each link after waste classification compared to before, serves as the basis for the allocation of carbon emission reduction contribution. Based on data of Shanghai, this article found that waste classification was a typical manifestation of achieving positive environmental externalities through the internalization of residents’ behavioral costs. Wet waste and recyclables generated relatively significant incremental investment in the sorting and disposal stage after waste sorting, which was an important factor affecting residents from maintaining their enthusiasm for waste classification in the initial stage. It also provided the proportion of contribution for different links, such as the residents’ contribution accounting for 70% in the dry and wet waste classification system and 86% in the recyclables classification system. However, in regions where both wages and housing costs are relatively low, and residents have already had a strong habit of submitting/selling recyclables, the contribution ratio of residents will drop to below 50%.

The application of domestic waste treatment and disposal technologies needs the support of engineering construction standards, but there are relatively few studies on the engineering construction standardization of domestic waste treatment and disposal. This paper systematically studied the current engineering construction standards of domestic waste treatment and disposal in China from three levels, including national standards, industry standards and local standards, and analyzed the current situation of them. It was found that the current engineering construction standard system of domestic waste treatment and disposal could not meet the needs of green and low-carbon development, promote resource utilization, build beautiful village, and construct smart sanitation. In combination with the requirements of the engineering construction standardization reform, a new engineering construction standard system of domestic waste treatment and disposal was established. The new system contained four sub-systems: mandatory national codes, basic standards, general standards, and special standards. Finally, according to the future development trend of domestic waste treatment and disposal, suggestions such as compiling relevant standards for carbon emission calculating of domestic waste treatment and disposal engineering, technical standards for small-scale domestic waste incineration treatment, and standards related to the construction of smart sanitation systems were put forward.