Based on the carbon accounting methods provided from The Guidelines for the Provincial Greenhouse Gas Inventories (Trial) and The 2006 IPCC Guidelines for the National Greenhouse Gas Inventories, combined with relevant data from the statistical yearbook and environmental sanitation planning of Shanghai, the direct carbon emissions of domestic waste in Shanghai from 2008 to 2035 were calculated. In 2021, the carbon emissions from domestic waste treatment reached 4.62 million tons of CO2e, with dry waste incineration accounted for 84% of the carbon emissions. According to the planned output and expected characteristics, the carbon emissions would continue to increase. As the continuous increase in the content of plastics in dry waste was an important reason for the increase of direct carbon emissions from domestic waste treatment, in the absence of considering the application of CCUS (carbon capture, utilization, and storage) technology, measures such as policy guidance and scenario optimization should be taken to ensure that less plastics would be incinerated. Taking the peak of direct carbon emissions reached in 2025 (with a peak of 5.83 million tons of CO2e) as an example, the control values for the per capita domestic waste output and the plastic content in dry waste in typical years were calculated.

Nowadays, the production of municipal solid waste (MSW) in China had accounted for 13% of the global production, which would make MSW treatments and disposal the key to achieving “waste-free city”,carbon peaking and carbon neutrality goals. Four main international carbon accounting methods were compared and sorted out, and their practicality and deficiency in carbon emission reduction accounting of MSW in China were analyzed. Proceed to the next step, based on the life cycle method, and on the basis of investigation and analysis of domestic and foreign cases, the carbon emission reduction path of MSW in China, such as optimizing the performance of incineration technology, enhancing utilization of landfill gas, using anaerobic digestion to treat kitchen waste, classification recycling and constructing MSW circular economy industrial park were put forward. The development direction of each path was prospected, aiming to provide theoretical support for the realization of green, low-carbon development in the whole life cycle of the MSW treatment industry during the 14th Five-Year Plan period.

he imbalance of influent C/N is common in urban sewage plants in China, which is an important factor restricting the denitrification of sewage. Adding extra carbon source to enhance denitrification process is an important measure to overcome C/N imbalance, but there were problems such as high cost and secondary pollution. Organic waste contained abundant carbon source substances, which were expected to replace fossil carbon sources used in sewage plants. It was conducive to the reduction and resource utilization of waste, while it could also reduce the cost of sewage treatment. The latest research in utilizing organic waste to produce carbon source both domestically and internationally was reviewed, mainly include food waste and fruit and vegetable waste. The key influencing factors of the carbon source process were summarize. The effects of pH, temperature, organic load, enzymes, and different pre-treatment technologies on the carbon source process were summarized. And the current application status of organic waste carbon source utilization technology in municipal wastewater, landfill leachate, aquaculture wastewater, and sludge fields were generalized, and look forward to the future development direction of organic waste carbon source utilization technology.

Food waste has the characteristics of high organic matter content, high waster content, and easy deterioration, which was easy to pollute the environment. The promotion of food waste treatment is conducive to the reduction, recycling and harmless of waste. In the study, the typical food waste treatment project in southeast coastal areas were mainly composed of food waste pretreatment system, anaerobic fermentation system, biogas purification system, sewage treatment system, boiler system and deodorization system. The operation effect of the project was influenced by the factors such as the quality of food waste collection, the characteristics of local diet (heavy matters was 1.4 times the average such as shell) and the volume of food waste collection and transportation (only have 1/4 design capacity on average). During the commissioning of the project, the pretreatment system was stuck seriously, the concentration of COD/ammonia nitrogen in biogas slurry of the anaerobic system was approximate to 2(<5), the sewage system needed to add a large number of carbon sources to maintain stable operation, and the sulfur load was less than 1/3 of the design led to the biological desulfurization system was not suitable for sludge inoculation. Through strictly controlling the quality of collection in the operation, adding additional equipment to the pretreatment system (gravel conveying line), adjusting the operation mode of biogas purification system(adjusted to alkali desulfurization) and using the three-phase separation liquid of the pretreatment system as the carbon source to allocate the sewage water inflow at the ratio of 1∶5~1∶10, etc, the stable and up-to-standard operation of the project could be ensured, the average gas production and methane concentration of the anaerobic system were 62 m3/t (into the anaerobic tank material) and 60%. The design and operation experience of the project could provide reference for other similar projects, and contribute to promoting the stable operation of similar projects at low cost and up to standards.

The management and resource utilization status of seven types of organic waste, such as food waste, garden waste, sewage sludge, fecal residue and waste water, crop straw, blue algae and other aquatic plant were analyzed. Several problems, such as low resource utilization efficiency, blocked industrialization channels and imperfect supervision system were raised. And some strategies were provided from the aspects of planning management, technical research, standard establishment and supervision system, in order to improve the efficiency of the resource utilization of organic waste in urban and rural areas.

The main steam temperature of the mechanical grate waste incinerator varied greatly during the initial period of operation (within 6 months). And the problem was analyzed from two aspects: by comparing with coal-fired boiler, it was found that the overall heat transfer temperature-pressure of superheater of waste heat boiler was smaller; and through the comparison of thermal calculation data of waste heat boiler in operation for 5 days and 6 months, it was found that the change of the heat transfer temperature-pressure of superheater was the main influencing factor of heat absorption of superheater. It was concluded that the large change range of the flue gas temperature at superheater inlet of waste heat boiler was the main influencing factor of the large change of heat transfer from superheater. The operation data showed that the inlet flue gas temperature of superheater during the initial period of operation could be increased by more than 100 ℃, the overall heat absorption of superheater increased by more than 60%, and the main steam temperature increased by more than 65 ℃. Finally, the feasible suggestions to reduce the change range of superheater inlet flue gas temperature and ensure the safe operation of superheater were put forward.

Pyrolysis/gasification is one of the important ways to convert Municipal Solid Waste (MSW) into energy and is also an effective way to dispose rural solid waste. High-temperature flue gas was used to directly heat up the preheated materials for pyrolysis/gasification. The influence of the temperature of heating flue gas and the preheating temperature of materials on the distribution of pyrolysis/gasification products were analyzed. And the influence of CO2 ratio in flue gas on the composition and calorific value of the combustible gas, and volatile release rate were emphatically analyzed. It was found that both preheating materials and increasing the temperature of flue gas could increase the yield and calorific value of combustible gas, promote the decomposition of macromolecular organics in the tar. When the preheating temperature was higher than 300 ℃ and the temperature of heatingflue gas was higher than 800 ℃, the calorific value of combustible gas was greater than 8.00 MJ/m3. The increase of CO2 content in the heating flue gas could significantly increase the CO content of the combustible gas, increase the calorific value of the combustible gas, promote the volatile release rate in the char, and improve the average voluetric heat transfer coefficient.

According to seven key design elements of the main factory building floor area, concrete reinforcement amount, pile foundation optimization, leachate spraying, main steam parameter selection, on-line soot blowing combined mode and station service power consumption rate of municipal solid waste incineration power plant, the optimization design ideas for the construction of new waste to energy plant were proposed from the angle of cost reduction and efficiency increase. Through the comparison and analysis of technical and economic indexes of several typical projects, seven recommended application modes or typical control values were formed on the optimization design of waste to energy plants with the scale of 500 t/d×1 and 500 t/d×2. Among which, main factory building floor area should be controlled at 12 000~19 000 m2, concrete reinforcement amount of main factory building should be controlled at 160~195 kg/m3, more than 25% of the pile foundation investment could be saved by selecting reasonable pile types and optimizing pile testing. Leachate spraying was applied to an incineration line, which could reduce leachate treatment system scale by 30 t/d，medium temperature and sub-high pressure parameters of 450 ℃ and 6.4 MPa should be applied to main steam. On-line soot blowing combined mode of “water spray soot blowing+steam soot blowing+shockwave soot blowing” should be applied to waste heat boiler, and the station service power consumption rate should be controlled at 14%~18%.

The concentrated ash was taken as the research object, HCl was used as the acid washing leaching agent to elute heavy metals into the acid washing solution. The effects of three heavy metal precipitators of flake alkali (NaOH), 30% NaOH solution, and Na2CO3 powder on the precipitation and recovery of Zn, Pb, Cu, and Cd in the acid washing solution were studied. The results showed that at pH 7~9, there was an increasing trend with the increase of pH, and the precipitation removal efficiency of NaOH type precipitants for heavy metals was much higher than that of Na2CO3 type precipitants; when pH>9, the growth trend of its removal rate became slow or slightly decreased. Among them, when the pH of flake alkali (NaOH), 30% NaOH solution, and Na2CO3 powder were 9, 10 and 10, the removal efficiency of the four heavy metals reached the peak, which were 97.95%, 98.71% and 99.41%, respectively. The removal efficiency of heavy metals by the three types of precipitants was not significantly different, but considering the engineering application value of cost, transportation, storage, and feeding, as well as safety production, flake alkali (NaOH) was used as a heavy metal precipitant. When the pH value of the reaction solution was adjusted to 10, the removal effect of heavy metals in the concentrated lime acid washing solution was the best, which was the most suitable for engineering application.

In order to develop a scientifically robust sampling scheme for identifying the hazardous characteristics of solid waste in the open air and visually represent the spatial distribution range of waste exceeding the super identification limit, a study was conducted at a large solid waste site. First, a waste sampling scheme was developed using ArcGIS to delineate the site boundaries, create grids, calculate central coordinates, and number the sequence. Then, the Environmental Visualization System(EVS) was utilized to generate 3D visual models of the terrain and the inorganic fluorides extraction toxicity respectively. The spatial ranges and quantities of inorganic fluorides exceeding the threshold were compared using four interpolation methods, including Kriging, Inverse Distance Weighting (IDW), Nearest Neighbor (NN), and Radial Basis Function (RBF). Finally, the accuracy of these methods was evaluated using the K-fold cross-validation technique. The findings indicated that the application of ArcGIS to develop the sampling scheme could considerably simplify the on-site workload. And there were differences in 3D visualization models constructed by the four EVS interpolation methods. Moreover, the Kriging method demonstrated the highest accuracy and offered a more realistic depiction of the space range exceeding the standard limits. And based on this, the amount of excess square was estimated.

With the rapid development of modern industry, hazardous waste pollution had become a prominent environmental problem. In order to comprehensively understand the current status and direction of hazardous waste research, the literature in the field of hazardous waste research in Web of Science and China National Knowledge Infrastructure databases was summarized and organized, and the current situation, frontier hot spots and development trends of hazardous waste research in the past 20 years were analyzed using bibliometric methods. The results showed that the scale of publications and scientific cooperation in the field of hazardous waste research had shown a steady increase, and many countries had shown a high degree of attention to it. China’s development in this field had accelerated since 2009, and had ranked first in the world in terms of the number of articles published and the scale of international cooperation. The bibliometric results showed that the current field of hazardous waste was mainly focused on the formulation of policy standards, disposal technology development and environmental impact assessment of pollutants. Adsorption, solidification/stabilization and co-processing were the main disposal technologies developed in this field.And the migration release and leaching toxicity of heavy metals, arsenic and dioxins were the hotspots in this field. Under the circular economy, the life cycle assessment which was conducive to the comprehensive utilization of hazardous waste, had begun to replace the previous one-sided and single research approach. The realization of hazardous waste reduction, harmless and resource utilization would become the starting point and primary goal of hazardous waste research in the future.

The laser ionization-time-of-flight mass spectrometry online detecting system for dioxins was used to continuously monitor dioxin emission in the flue gas of a circulating fluidized bed incinerator. The effect of different operating conditions on dioxin emission was explored. The results showed that increasing the amount of activated carbon from 10 kg/h to 30 kg/h slightly reduced the concentration of dioxin. And the steady-state concentration of dioxin only decreased by 13.33%. The inhibitor could make high dioxin emission caused by abnormal conditions return to the normal low emission more quickly. After reducing the amount of treated solid waste and adopting auxiliary combustion measures, the dioxin emission became low and stable, with an average TEQ concentration of 0.028 ng/m3. It was an effective way to control dioxin emission by stabilizing the combustion condition, fully burning solid waste and reducing dioxin generation from the source. The correlation between dioxin and 14 boiler operating parameters was weak. Dioxin emission was a comprehensive problem, which was related to many factors and could not be judged by a single parameter.

The farmland soils along the main highways around Changchun City was taken as the research object, the environmental risk research was carried out. Through studying the content and types of polycyclic aromatic hydrocarbons (PAHs), the distribution characteristics and sources of PAHs were analyzed, in order to provide references for the treatment of PAHs pollution in Changchun area. The results showed that the total content of PAHs ranged from 0.85 mg/kg to 45.86 mg/kg, the main source of PAHs was biomass combustion source, while petroleum source and petroleum combustion source existed simultaneously.50% of the agricultural soils in the study area had a certain degree of PAHs contamination risk that required attention.

The effectiveness of the waste sorting policy in Beijing was evaluated through literature review, questionnaire surveys, and cost analysis. The collection and treatment situations of domestic waste in Beijing before and after the implementation of the waste sorting policy was compared, and the current state and existed issues of waste management in Beijing were analyzed. The results showed that, on the one hand, the implementation of the waste sorting policy had promoted waste reduction and resource utilization, and improved residents’ environmental awareness. On the other hand, although the existed domestic waste treatment facilities could match the current disposal situation, with the progress of waste sorting work and the construction of new waste treatment facilities, incineration companies may face the situation of “not having enough waste to burn”. Therefore, it was necessary to balance the advantages and disadvantages of waste sorting and facility construction, further optimize the layout and make reasonable plans. Based on this, fully considered the opportunities and challenges faced by the implementation of waste sorting policies in Beijing, countermeasures and suggestions were proposed for promoting waste sorting in Beijing from multiple aspects, such as improving the quality of classification, adjusting facility construction, innovating sorting modes, and establishing coordination mechanisms, in order to provide theoretical and practical basis for urban domestic waste management planning and policy making.

In order to analyze the management mode of MSW in typical small and medium-sized cities in China and the existed problems， Xilinhot City was taken as an example， the current integrated management method of MSW was summarizd， the management level of MSW was analyzed combining with the classification. And the problems and possible solutions of MSW management in Xilinhot City were discussed through sampling survey of residents. At present， Xilinhot takes the Municipal Environmental Sanitation Management Office as the main organization of MSW management， the classification was at the initial stage， and the harmless treatment relied on sanitary landfilling. It was found that there were problems such as the lack of residents’sense of belonging to environmental responsibility， the lack of supporting facilities for waste sorting， the social atmosphere was not strong， and the effectiveness of publicity work was not ideal. It was suggested to improve the system and the refined management level of the whole process， gradually increase the investment in the construction of classification infrastructure and match the end classified disposal facilities； introduce social forces to build a joint investment mechanism； formulate targeted publicity strategies and reward and punishment measures to enhance residents’ sense of responsibility.

Suzhou Vortexinfo Technology Co. Ltd.; Anhui Biaoke Environmental Technology Co. Ltd.