Quantitative decision-making methods based on carbon emissions and economic analysis have played an important role in the selection and decision of solid waste treatment and disposal technology. A medium-sized city in Yangtze River Delta was taken as an example, the selection method of multi-source organic solid waste(municipal sludge, food residue, kitchen waste) collaborative treatment and disposal was explored. Different organic solid waste treatment and disposal process combinations were established based on life-cycle theory, and the carbon emission and economic cost were analyzed. On this basis, the feasible solution of low carbon emission and low economic cost was obtained by using linear goal programming method. The results showed that under the lowest carbon emission scenario, it was recommended that all kinds of organic solid waste should be treated with anaerobic digestion, but different disposal methods should be selected for biogas residue. Under the lowest economic cost scenario, compost or incineration was a better option, but if you rely on existing facilities for co-composting or incineration, the amount of co-consumption should be considered.

In the context of the national development strategy of carbon peak and carbon neutrality, municipal solid waste management departments need to adopt carbon emission reduction models in waste management as an entry point and act proactively. Therefore, taking Chengdu as an example, this paper calculated a total of 2 780.40 Gg of carbon emissions would be generated in the domestic waste treatment process in Chengdu in 2021 according to the measured and domestic literature parameters. The net carbon emission rate for landfilling was 794.00 kg/t, while for incineration, it was 0.934 kg/t. By calculating the carbon emissions from landfills (excluding leachate treatment) and incineration (excluding leachate,fly ash,and slag treatment), it was found that the IPCC’s theoretical calculations were 34% and 53% higher than the measured values and the literature parameters, respectively. For food waste treatment, anaerobic digestion is more suitable than aerobic composting. Under the current scenario, Chengdu’s net carbon emissions in 2021 was 784.95 Gg/a, and the net carbon emissions in 2030 and 2060 would be 457.31 Gg/a and 246.26 Gg/a, respectively. The net carbon emission rate of “zero landfill+food waste aerobic composting+rest waste incineration power generation” scheme （Scenario 1） was 113.02 kg/t in the base year (2021), and the net carbon emission rate in 2030 and 2060 would be 57.83 kg/t and 27.01 kg/t, respectively. Using the “zero landfill+anaerobic fermentation of food waste+remaining waste incineration power generation”scheme (Scenario 2),the net carbon emission rate in the base year (2021) was 111.10 kg/t, and the net carbon emission rate in 2030 and 2060 would be 49.31 kg/t and 14.73 kg/t, respectively. The net carbon emission rate of the “zero landfill+anaerobic digestion of food waste+remaining waste incineration power generation+recyclable resource rebate” scheme (Scenario 3) was -156.10 kg/t in the base year (2021), and the net carbon emission rate in 2030 and 2060 would be -256.73 kg/t and -229.08 kg/t, respectively. Carbon emissions in the process of municipal solid waste treatment can be effectively reduced and carbon neutrality achieved through source reduction, classification collection and treatment, recycling of recyclable waste, anaerobic digestion of kitchen waste, incineration power generation of municipal solid waste, zero landfilling, and landfill gas collection and utilization.

In order to realise the resourceful use of landfill humus, the humus from a domestic waste landfill in Shenzhen was taken as the raw material to replace quartz sand, and a combination of dry and wet production process was adopted to prepare high modulus and high quality industrial water glass. The results showed that the humus was an ideal silica source for the preparation of water glass, the content of silica in the silica gel after acid leaching could reach 72.81%. When the mass ratio of sodiun carbonate to humus was 1∶1, the calcination temperature was 850 ℃, the calcination time was 120 minutes, the liquid-solid ratio was 8, the concentration of NaOH was 2%, the hydrothermal temperature was 160 ℃， and the hydrothermal time was 4 hours, the high-modulus water glass with a modulus of 3.03 could be prepared， which reached the standard of superior quality as stipulated in the industrial liquid waterglass L280-41 of GB/T 4209—2022 Sodium Silicate for Industrial Use.

The humus soil of an aged landfill in Jishui county was taken as the research object to explore the physics-chemistry properties and leaching solution, in order to provide an effective way for its resource utilization. The results showed that the content of lime soil, brick and stone components in waste humus was as high as 93.62%, and the content of glass and plastic was 6.38%. The humus was sandy soil with good thermal stability. The results of XRD and EDS showed that the main chemical components were SiO2, Al2O3, FeO and CaCO3, while the main mineral components were quartz, calcite and so on. The content of organic matter in humus was 15.4%. Heavy metals including chromium,zinc and arsenic exceeded the standard,and the leaching concentration of arsenic and plumbum also exceeded the standard in different degrees. The pH of humus after curing by lime-cement was greater than 12, which was beneficial to accelerate the decomposition of organic matter. Its unconfined compressive strength was 1.7-3.1 MPa, while the total content of lime and cement more than 10% could meet the filling requirements of JTG D50—2017 Specifications for Design of Highway Asphalt Pavement for medium and light traffic base and subbase of secondary and below secondary roads, which had the potential to be used as road filling materials.

The effects of different ratio of dead animals meat to fruit and vegetable waste on the growth performance of black soldier fly larvae were studied. The study found that the waste meat as a substrate had high nutritional value. It met the relevant safety standards of feed, showing the potential of resource utilization. Through experiments, it was also found that the waste meat to fruits and vegetables with a mass ratio of 3∶1 was optimal, which could significantly improve the weight per larvae, the conversion rate and the survival rate of feed worms, reaching 100 mg/piece, 22.0% and 80.9%, respectively. In addition, the crude protein content of the dried black soldier fly reared in this mixed ratio was as high as 40.64%, and the essential amino acid index (EAAI) reached 0.88, indicating that it was a good source of protein feed. Studies have also pointed out that leucine was the first limiting amino acid, and the second limiting amino acid was histidine or lysine, which was recommended to be supplemented in practical applications. The research results provide a scientific basis for the resource utilization and high-value utilization of dead animals meat, as well as improve the economic benefits of solid waste sanitary treatment plants.

Typical aquatic organic waste Myriophyllum verticillatum samples were pressed at a pressure of 0-10 MPa, and the water content of the dewatered samples and the quality of the filtrate were examined. The results found that when the pressing pressure was 2.5 MPa, the mass of Myriophyllum verticillatum could be reduced by 53.85% and the volume reduced by more than 80%. The COD, suspended solids concentration and total phosphorus content in the press filtrate could not meet the Class III water discharge requirements of GB 3838—2002 Environmental Quality Standards for Surface Water, and further treatment was needed. The protein content could reach more than 200 mg/L, which has certain potential for resource utilization. The organic components of lake water and leachate include protein-like, fulvic acid-like and humus-like substances. Among them, the lake water was dominated by protein-like substances, while the content of fulvic acid-like and humus-like substances in the leachate was significantly higher.

The bioconversion of kitchen waste by black soldier fly (BSF) is one of the effective approaches to further utilize the kitchen waste. However, the supply issue of commercial BSF eggs has become a potential instability factor in BSF breeding operation. Therefore, the potential and feasibility of large-scale self-produced insect eggs for converting kitchen waste was researched. The results indicated that using self-produced BSF eggs could increase 5.6 percentage points of larvae conversion and 12.9 percentage points of solid waste reduction efficiency with the dosing ratio of 1∶7 500, which higher than those of purchased eggs, reaching 19.4% and 60.3%, respectively. The protein and lipid content of the larvae were 43.9% and 20.2%, respectively. Further, based on the results of single-factor optimization experiments with egg-to-waste ratio and economic benefit analysis, an optimal ratio of 1∶7 500 was determined. Additionally, taking a 50 t/d waste treatment project by BSF as the basis for calculation, the construction and operation costs of setting up a spawning house were estimated. The operational cost of self-produced BSF eggs was approximately 0.60 yuan/g, which was lower than the market price of 0.80 yuan/g, with an expected annual saving of 0.864 million yuan. Comprehensive analysis showed that establishing a spawning house to achieve self-supply of BSF eggs was feasible and necessary for the large-scale BSF conversion project.

The organic slurry from wet waste exhibits a “high carbon to low nitrogen”characteristic, making it suitable as an external carbon source to address the carbon-nitrogen ratio imbalance in leachate treatment plants. The experiment of hydrolytic acidification and stepwise filtration pretreatment of organic slurry was carried out in this study. The effects of pH, temperature, and hydrolysis acidification time on the preparation of acidizing fluid from wet waste organic slurry were investigated. The results showed that the optimal acid production conditions for acid production were temperature of 35 ℃, pH of 6, and a hydrolysis acidification time of 4 days, according to actual factors such as site, turnover cycle and economic costs, under which the concentration of VFAs reached 36 g/L, and the VS to VFAs conversion rate was 26%. Additionally, pH significantly affected the composition of fermentation products. At a moderate temperature of 35 ℃ and pH levels of 5.0, 6.0, and 7.0, butyric acid was the dominant product at the end of fermentation, followed by acetic acid and propionic acid. In the stepwise filtration experiments, it was recommended to pre-filtering the slurry using dual filtration with pore sizes of 1.0-2.0 mm and 0.2-0.5 mm, to prevent the rapid decline in membrane flux caused by ceramic membrane blockages.

The integrated treatment technology of desulfurization and denitrification in the furnace of waste incineration power plant is to inject denitrification and desulfurization agents into the furnace of waste incinerator at the same time to remove NOx and SO2 from the source of pollutant generation. In this study, the collaborative control of multi-pollutants in large-capacity incinerator flue gas was taken as the research object, and the emission characteristics of NOx and SO2 were analyzed under the conditions of no desulfurization and denitrification process, using high-temperature denitrification agent and high-temperature desulfurization agent alone, adopting the process of “high-temperature desulfurization+semi-dry deacidification” and using desulfurization and denitrification agents collaboratively. And the economic costs of traditional process and the integrated process of desulfurization and denitrification were compared. The results showed that when 0.5 g/m3 denitrification agent and 0.9 g/m3 desulfurization agent were injected into 750 t/d furnace at the same time, the denitrification efficiency and desulfurization efficiency could reach above 74% and 84% respectively, and the daily average of NOx emission index could be lower than 100 mg/m3, and the daily average of SO2 emission index could be lower than 50 mg/m3. When the process of “high-temperature desulfurization+semi-dry deacidification” was adopted and the lime slurry flow rate was fixed at 2 000 L/h, the SO2 emission concentration at the chimney outlet could be stably controlled below 20 mg/m3. The technical and economic analysis showed that compared with the traditional boiler tail flue gas treatment processes, the integrated process of desulfurization and denitrification in the furnace was simple and low cost, which could not only reduce the consumption of chemicals, but also reduce investment costs by 90% and operating costs by 59%. It had a good application prospect in the source control of NOx and SO2 emissions.

A plasma melting furnace of a 10 000 t/a solid waste disposal system in Guangdong province was taken as an example, the auxiliary spray gun hydraulic model test and industrial application of the hazardous waste plasma melting furnace were carried out by setting up a hydraulic model test platform. The results showed that as the spray gun load increased, the penetration depth, splash height, amplitude and material discharge ratio gradually increased. As the height of the spray gun arrangement increased, the penetration depth, splash height, amplitude and material discharge ratio gradually decreased. Compared with the staggered layout schemes, the penetration depth, splash height, amplitude and material discharge ratio of symmetrical layout were smaller. Finally, the auxiliary gun design scheme of the prototype furnace body was determined as the gun layout height was 250 mm and symmetrical layout. According to this plan, the on-site renovation achieved the expected effect, with 28.6% reduction in plasma torch power consumption, 13.2% reduction in system power consumption after considering oxygen preparation, and 9.8% reduction in hourly operating costs.

The ash deposition and coking on the heating surface of a waste incineration boiler brings great challenges to the long-term stable operation. In order to take a reasonable and effective way of ash cleaning to extend the life of boiler heating surface, an experimental study of the shock pulse generators technology applied to clean ash in the second and third flue of a 660 t/d waste incineration waste heat boiler was carried out, and the effects of different ash cleaning modes on flue gas temperature were compared. The results showed that, in the comprehensive consideration of the ash cleaning effect, ash cleaning profit and the impact on the working conditions, operate normal mode at a frequency of once a day was the best plan, the outlet flue gas temperature of the second flue was reduced by about 10 ℃, and the flue gas temperature in the middle of the third flue was reduced by about 40 ℃ during long-term application. The results of this study can provide a reference for the selection and application of ash cleaning technology for waste incineration waste heat boilers, which can help to achieve the goal of its long-term stable operation.

As a new pollutant, antibiotic resistance genes (ARGs) pose a risk of accumulation and spread in food waste. Among the common treatment technologies of food waste, aerobic composting is not only simple to operate, but also can realize resource utilization on the spot and nearby, and can effectively reduce ARGs in food waste and control their spread, meanwhile, which is of great significance to achieve sustainable development, protect human health and ecological environment. At present, most studies mainly focus on the ARGs reduction in aerobic composting of organic solid waste, such as livestock manure and sludge, and relative research on food waste is not deep enough. The types of ARGs in food waste and its aerobic composting process, the transmission paths and mechanisms of ARGs among humans, animals, plants and food waste were reviewed, and the impacts of physicochemical parameters (temperature, water content, pH, O2 content, C/N ratio and granularity of raw material, etc.) and exogenous additives (microbial agents, leavening agents and biochar, etc.) on the reduction of ARGs during composting were systematically analyzed. Meanwhile, some possible future research directions, such as strengthening the exploration of the relationship between physicochemical parameters and the growth and decline of ARGs, and studying the propagation mechanism of ARGs under different environmental conditions were proposed, which could provide theoretical references for the further optimization of composting technology of food waste, the control of the spread risk of ARGs and improvement of ARGs reduction effect.

Taking the stockpiled waste excavation project of a domestic waste sanitary landfill in South China as the analysis object, according to the hydrogeology of the landfill, the anti-seepage system and the physicochemical characteristics of the stockpiled waste, a modular and automated oxygen injection stabilization pretreatment system was designed in a phased, zoned, and layer-by-layer manner. This could enable the waste excavation unit to form an aerobic bioreactor and increase the conversion speed from anaerobic state to aerobic state. The stabilization goal could be achieved within a short period (less than 35 days), which is convenient for the subsequent excavation and transportation of stockpiled waste. Through the monitoring and control means of oxygen injection stabilization pretreatment, the concentration of methane gas in the waste pile was less than 3%, the odor concentration limit in the natural exhaust of the excavation unit met the requirements of GB 14554—1993 Emission Standards for Odor Pollutants, and the leachate head in a single-layer waste pile was less than 40 cm. At the same time, a large amount of degradable substances in the stockpiled waste were degraded, and the BDM index had a large drop compared with that before oxygen injection stabilization pretreatment.

Since 2019, China has fully launched municipal solid waste（MSW） classification in cities at the prefecture level and above, but there is still a lack of economic benefit analysis for MSW classification in large and medium-sized cities. Economic benefits of MSW classification in Zhanjiang city by using the cost-benefit methods were evaluated. For the revenue unit, the economic benefit of recyclables after being included in the government supervision system were the highest (221.19-342.25 million yuan/a). Followed by the economic benefit (49.47 million yuan/a) from front-end recovery of recyclables which were assumed entering the end-treatment facility. The economic benefit of different recycling paths of food waste were quite different, specifically, 100% anaerobic digestion (20.33 million yuan/a)>50% composting+50% insect rearing (17.42-19.00 million yuan/a)>100% composting (4.73-7.89 million yuan/a). Furthermore, based on the cost-benefit method and referring to the specific indicators in Zhanjiang Urban Solid Waste Classification Special Plan (2020—2035)，it was indicated that Zhanjiang MSW classification work could achieve net income in the fifth year (2040) after the second fixed investment. This study filled the gap in economic benefit analysis for Zhanjiang city’s MSW classification and could provide a reference for other large and medium-sized cities to calculate the economic benefit of MSW classification.

The generation of packaging waste in four typical waste-producing industries including electronic components, food manufacturing, furniture manufacturing and medical manufacturing were investigated, in order to find out the generation and disposal practices of packaging waste in these industries, encompassing the types of packaging waste, the amount generation, and the methods of recycling and disposal. Meanwhile, the existing problems in packaging waste reduction and resource utilization were analyzed, while the countermeasures and suggestions of reduction, management and utilization were put forward, which could provide a basis for promoting the standardized management of packaging waste in industrial enterprises.