The organic components in municipal solid waste (MSW) can be classified into biogenic and fossil-derived fractions. Only carbon emissions from the combustion of fossil-derived components are accounted for in the carbon emissions from waste incineration. Online monitoring of carbon sources in complex waste streams is essential for accurately assessing the carbon emissions and reduction benefits of WtE incineration plants. Based on the characteristics of China’s waste incineration processes, an online monitoring method for the carbon sources of incinerated waste in WtE plants using energy-mass balance principles was developed. A case study was conducted at a WtE plant in Zhejiang province, where radiocarbon (14C) comparative experiments were carried out to validate the accuracy and sensitivity of the method under actual operating conditions. Furthermore, a systematic analysis was performed to quantify the carbon source composition and carbon emissions of the waste at the plant. The results indicated that for the No.2 incinerator (with a daily processing capacity of 750 tons) in 2023, the monthly average proportion of biogenic components in the waste exceeded that of fossil-derived components by 7.10-18.74 percentage points. The annual incineration of waste generated a total of 87.3 thousand tons of fossil-derived carbon emissions, with the fossil carbon emission factor (in terms of CO2) per ton of waste ranging from 277.55 kg/t to 421.56 kg/t. Additionally, the findings further demonstrated the limited applicability of default values in existing carbon emission methodologies. The online carbon source monitoring method established in this study provides a methodological foundation for carbon emission accounting and real-time monitoring in WtE incineration plants.

With the advancement of municipal solid waste classification, the cost and greenhouse gas emissions associated with waste collection and transportation have become critical challenges. This study focused on the impact of different collection and transportation modes (direct transport and indirect transport) and vehicle types (electric and diesel) on the costs and greenhouse gas emissions in this process, aiming to provide optimization strategies and decision-making support for urban waste management and contribute to the achievement of green and low-carbon development goals. Based on field investigations and real vehicle test data, a system dynamics model was developed using Anylogic software to compare and analyze the differences in cost and greenhouse gas emissions between food waste and residual waste under different collection and transportation modes, and to evaluate the impact of type selection of collection and transportation vehicles. The results indicated that for food waste collection and transportation, the emission reduction potential of electric vehicles was significant, with emissions approximately 44.49% lower than those of diesel vehicles, albeit at a slightly higher overall cost. For residual waste collection and transportation, the direct transport mode costs reduced by 28.02%-33.02%, and GHG emissions reduced by 27.69%-28.96% compared to the transfer transport mode. In practice, shortening collection and transportation distances, optimizing the layout of transfer stations and improving transportation routes could effectively reduce energy consumption and emissions. The research findings could provide reference and methodological support for the planning and design of urban waste collection and transportation systems, as well as for vehicle selection and policy formulation.

In the context of the “dual carbon” goals, accurately accounting for and reporting carbon emission data is crucial for developing effective emission reduction policies. To verify the reliability of carbon emission data from coal-fired power plants in China, by comparing the data discrepancies between the incoming coal and the coal fed into the furnace, and applying statistical methods for quantitative analysis, a method was proposed to validate the reliability of carbon emission data obtained by the mass balance approach. The reliability of this method was tested through case studies of two power plants (Plant A and Plant B) in Zhejiang province. The results showed that although the correlation between the incoming and furnace-fed coal data in Plant A for 2022 and 2023 (the determination coefficients of carbon content, incoming/consumed quantities, and carbon emission were 0.76/0.80, 0.81/0.95, and 0.82/0.96, respectively) was significantly stronger than that of Plant B (-0.03/0.25, 0.54/0.64, and 0.43/0.66), this difference was due to the varying magnitudes of the time lags between coal entering the plant and entering the furnace at the two plants. This discrepancy increased the difficulty of assessing data estimation errors, but by applying appropriate statistical methods, the reliability of carbon emission data from different power plants could be effectively evaluated using a unified standard. And the carbon emission data from both Plant A and Plant B were verified as reliable.

Effective treatment of toilet feces is an important aspect of rural environmental sanitation remediation. In order to efficiently realize the aerobic composting of toilet manure in rural areas of the Qinghai-Xizang Plateau, based on the physical and chemical characteristics of manure, household dry-toilet manure and highland barley straw in rural areas of the Qinghai-Xizang Plateau were selected as compost raw materials, and the effects of four factors, namely C/N, decompose clinker (dry-toilet manure, highland barley straw, mature compost) addition ratio, moisture content, and ventilation mode on aerobic composting of dry-toilet manure were investigated through orthogonal experiments. The results showed that the manure of rural dry-toilet in the Qinghai-Xizang Plateau had the characteristics of high moisture content, high organic matter content, low C/N, low heavy metal content, and low seed germination index, and had good potential for compost recycling. The influence of various factors on the aerobic composting of dry-toilet manure in rural areas of the Qinghai-Xizang Plateau was C/N > the proportion of decomposing clinker > moisture content > ventilation mode. The optimal process parameters were as follows: the C/N ratio was 30, the proportion of compost raw materials (dry-toilet manure∶highland barley straw∶mature compost) addition was 2.0∶0.7∶0.3(in terms of wet weight), the moisture content was 55%, and the ventilation mode was continuous ventilation (ventilation rate was 0.42 L·min?1·kg?1). This research work provides a theoretical basis for the efficient resource utilization of household dry-toilet manure and highland barley straw in the rural areas of the Qinghai-Xizang Plateau, and is of great significance for promoting the construction and sustainable development of local beautiful villages.

With the progress of domestic waste classification and resource recovery in China, acidogenic fermentation of kitchen waste for resource utilization is confronted with problems such as low efficiency and difficulties in the utilization of fermentation liquid. The synergistic effect of mixed bacterial strains was utilized to enhance the acid production efficiency of kitchen waste fermentation and evaluate the possibility of resource utilization of the fermentation liquid as a carbon source for denitrification. With volatile fatty acids (VFAs) yield and chemical oxygen demand (COD) concentration as vital indicators, the impacts of microbial strain ratios and initial pH of kitchen waste slurry on acidogenic fermentation performance of kitchen waste were assessed. Results showed that with yeast, Acetobacter, Bacillus licheniformis, and Bacillus subtilis being co-inoculated at a ratio of 1.0∶0.5∶3.0∶4.5,under 30 ℃ with an initial pH of 8 for the kitchen waste slurry, peak VFAs concentration showed a 284.5% increase relative to the control group, whereas the biochemical-to-chemical oxygen demand (B/C) raised from 0.54 to 0.92. It indicated that the mixed bacterial strain significantly enhance the hydrolysis and acidification rate of macromolecular organic substances. Denitrification assays further verified that the denitrification performance of the composting liquid from kitchen waste was basically the same as that of industrial glucose, which proved that the composting liquid from kitchen waste enhanced by the mixed microbial agent is an economical, efficient and stable alternative carbon source.

As an abundant biomass resource, the high-efficiency energy/resource utilization and proper disposal of straw possess has great significance in achieving the “dual carbon” goals. Straw is rich in organic matters, which can be used as raw material for producing high-value bio-based products through bioconversion processes. However, the complex and recalcitrant lignocellulosic structure limits its bioconversion efficiency. Therefore, appropriate pretreatment is a crucial step for high-efficiency bioconversion of straw. Based on the above analysis, this review systematically summarizes the advantages, limitations, and technological breakthroughs of the developed straw pretreatment technologies, and discusses the potential engineering applicability, economic feasibility and environmental sustainability of the integrated approach for directional enzymatic hydrolysis and bioconversion of straw, which is based on the in situ preparation of microbial consortium-based compound enzyme. Leveraging the multiple advantages of the microbial consortium-based compound enzyme, the proposed integrated approach can effectively reduce the pretreatment cost and enhance the bioconversion efficiency of straw. Although there are still some technical challenges in practical application, with the continuous advancement of relevant biological technologies, the proposed approach has the potential for large-scale industrial application.

Trace metal elements (TME) play a crucial regulatory role in the synthesis of enzymes and metabolic activities of microorganisms within anaerobic digestion systems. The efficiency of TME in the three stages (hydrolysis and acidogenesis, acetogenesis, methanogenesis) of anaerobic digestion was comprehensively evaluated. It was concluded that TME not only promoted the hydrolysis efficiency of granular organic matter and enhanced the metabolic activity of acidogenic bacteria, but also significantly improved system stability and methane production by dynamically regulating the metabolic balance between acidogenic and methanogenic bacteria. Due to the typical characteristic of low-concentration promotion and high-concentration inhibition of TME in the digestive system, its dosing strategy was difficult to quantify. Therefore, the effects of key parameters such as substrate organic composition, inoculum sludge properties, temperature, organic loading rate, and TME addition methods on the requirement of TME dosing strategy were further investigated. The effective methods for changing the chemical form of TME and improving its bioavailability through chelating agents were further summarized. The potential of extracellular polymers (EPS) as natural green ligands was particularly explored, its rich functional groups could effectively regulate the bioavailability of TME through mechanisms such as electrostatics, complexation and adsorption, providing a new perspective for optimizing the TME dosing strategy.

This study designed and operated a 100 m3/d thermal extraction deammonification system for treating anaerobic digestate from a food waste recycling project. The effects of inlet position, ammonia reflux, and operating temperature on deammonification efficiency were investigated through pilot-scale experiment, and equipment clogging after operation was further revealed. The system operated for 50 days, treating a total of 4 086 m3 of digestate with a treatment load of 4.14 m3/h. The comprehensive cost of treating digestate using thermal extraction deamination system was calculated to be approximately 23.59 yuan/t, with an average deammonification efficiency of 58.92%. The significantly increased COD/NH4+ ratio for deammonification biogas slurry indicated that it could reduce carbon source addition during the treatment process of digestate deamination. The results demonstrate that the thermal extraction deammonification process is feasible for treating anaerobic digestate and can be further engineered for application in food waste resource recovery projects.

This study focuses on the performance and environmental safety of municipal solid waste incineration (MSWI) fly ash melt-derived products as aggregates in cement concrete pavement. Through a process of “electric furnace melting followed by forced washing” applied to a mixture of fly ash and quartz sand (at a ratio of 100.0∶17.6), vitrified slag was produced. This slag was subsequently sieved and its gradation optimized for use in mortar specimen preparation, followed by characterization of its fundamental physical and chemical properties. The results demonstrated that the mortar specimens prepared with the optimally graded vitrified slag achieved a 28-day compressive strength of 32.9 MPa and a wet density of approximately 2.5 t/m3, meeting the mechanical requirements for road construction materials. Under simulated acid rain conditions (pH = 4.32), the leached concentrations of Cr, Ni, Cu, Zn, As, Cd, Pb, and Mn were all significantly lower than the limits stipulated in the Technical Requirements for Solid Waste Vitrification Product (GB/T 41015—2021). Predictions based on the US EPA 1315 semi-dynamic leaching test indicated exceptionally low cumulative leaching amounts over 15 years, with Zn showed the highest value at 2.12 mg/kg and Cd the lowest at 0.001 mg/kg. The accelerated leaching method established in this study showed a deviation of less than 10% compared to the long-term predicted results, verifying its validity. The vitrified slag demonstrates strong potential for application as an aggregate in cement concrete pavement.

The feasibility of co-melting municipal solid waste incineration (MSWI) fly ash with red mud and its synergistic effects on heavy metal immobilization were systematically investigated. Through analysis of the chemical composition, co-melting characteristics of fly ash and red mud, and the compositions of the melting products and its leaching toxicity, the effects of high-temperature co-melting treatment on both melting temperature reduction and heavy metal stabilization were evaluated. The experimental results demonstrated that the co-melting process could significantly reduce the flow temperature from above 1 500 ℃ to approximately 1 250 ℃ and shorten the melting process of fly ash. The main molten products were complex silicate minerals, including Alinite, Wadalite, and double perovskite. Leaching tests conducted that the molten treatment had a significant solidification effect on most heavy metals, and the leaching concentrations were all below the relevant standard limits. These findings collectively suggest that the co-melting treatment of MSWI fly ash with red mud represents an effective approach for waste treatment, providing a innovative pathway for achieving “waste treatment with waste”.

With increasingly stringent emission standards and requirements for co-combustion of industrial solid waste, traditional deacidification processes face challenges such as high operational load, low lime utilization efficiency, increased fly ash generation, and tightening emission compliance pressures. This study established a three-stage collaborative acid gas removal system (furnace dry process + semi-dry process + wet process) by integrating a furnace dry process into the existing flue gas treatment process. The coupling performance was systematically investigated by dynamically adjusting the calcium-to-sulfur ratio (Ca/S). Results showed that the removal efficiencies of SO2 and HCl by the furnace dry process increased with rising Ca/S, reaching 89% and 66%, respectively, at Ca/S=1.52. Reasonable control of Ca/S (0.8-1.0) reduced the subsequent semi-dry process slurry volume and wet process alkali solution consumption, while decreasing system fly ash generation (fly ash rate reduced from 2.68% to 2.33%) and total acid gas removal costs. Taking the in-furnace dry process injection volume of 200 kg/h of desulfurizer as an example, the operational cost for acid gas removal per ton of waste decreased by 1.12 yuan, with daily fly ash disposal costs reduced by 9 908 yuan. This study demonstrates that the furnace dry process, as a front-end technology, achieves integrated “waste reduction, cost reduction, and efficiency enhancement” through high-temperature rapid reactions and collaboration with back-end processes,while ensuring compliance with emission standards. It provides an efficient and economical flue gas treatment solution for waste incineration plants co-incinerating industrial solid waste.

Waste-to-energy(WTE) has become the mainstream way of waste treatment method in China. Improve the energy efficiency of waste incineration power plants is currently the focus of the operation of the waste incineration industry in the context of “dual carbon”goals. The different waste heat utilization technology routes and their advantages and disadvantages were discussed. And a certain waste incineration power plant in Northeast China was taken as the research object to analyse the waste heat utilization effect. Results indicated that the adoption of waste heat heating technology enabled the overall plant efficiency to exceed 50% during the winter heating period, with a maximum efficiency of up to 71.33%. The utilization of waste heat for heating in waste incineration power plants could improve the social environmental benefits, economic benefits and carbon emission reduction benefits of the incineration plant. During a single heating season, 25 000 tons of standard coal could be saved, and the carbon emission reduction was approximately 66 000 tons. The research aims to provide references and inspirations for promoting the technical optimization of waste incineration equipment and systems, and enhancing the development level of the industry.

In response to the problems of low collection efficiency and energy waste in food waste pretreatment workshops, in combination with the actual case of a harmless treatment plant for food waste in a certain county，the computational fluid dynamics (CFD) technology was employed to carry out numerical simulation of the airflow organization in the workshop. By establishing a 1∶1 physical model (workshop dimensions was 66.65 m× 34.50 m×13.40 m), the influence of ventilation frequency and air outlet layout on the air flow distribution were compared and analyzed under four working conditions with varying numbers of open discharge doors (0-3 doors). Results showed that exhaust vents was concentrated at a height of 6.00 meters from the center, and the supply air outlet (at a height of 2.50 meters) had insufficient air volume and its location was unreasonable, which caused significant dead zones at the 1.50 meters personnel breathing height on the first floor, and the dead zone was the largest under condition 4 (three doors all open). The mechanical supply air volume was only designed to be 50% of the exhaust air volume, and the supply air cannot penetrate the equipment-obstructed areas, resulting in insufficient air turbulence. By adjusting the positions of the supply/exhaust vents and increasing the proportion of low-altitude air supply, it is possible to reduce ineffective ventilation while meeting the requirement that the wind speed in the door opening be greater than or equal to 0.3 m/s. This also helps to decrease the equipment footprint and energy consumption.

To understand the groundwater environmental status around waste incineration plants in Xi’an, pH and the contents of Fe, Mn, Cu, Cd, Pb， Ni, As， Se in the collected groundwater samples were measured. The Nemerow comprehensive pollution index and entropy weight water quality index were used to evaluate the pollution status, and the health risk model was combined to assess the health risks caused by different exposure pathways. The results showed that in groundwater during the wet season, normal season and dry season in this area, Cd had the lowest content, while Fe had the highest content. In the study area, the Fe and Mn contents at the GL-N groundwater point exceeded the standard, while the other points did not exceed the standard. The pH value ranged from 6.88 to 8.16, all complying with class Ⅲ standards specified in GB/T 14848—2017 Standard for Groundwater Quality. According to the Nemerow index, only the GL-N point showed mild pollution due to the exceedance of Fe and Mn standards, while other points were in a clean level. The entropy weight water quality index indicated that the overall water quality in the region was excellent, and Fe and Mn contributed 78.6% to the pollution at the GL-N point. Health risk assessment showed that in non-carcinogenic risks, As and Cd had the highest hazard quotients,but both were less than 1. All carcinogenic risk values were below the threshold 10-6, with the carcinogenic risk of As being higher than that of Cd. Drinking water was the main exposure pathway for Cd, and children were more sensitive to Cd.