A comprehensive emission inventory of hazardous air pollutants from municipal solid waste incineration in China

Graphene Derived from Municipal Solid Waste

Landfilling is long the most common method of disposal for municipal solid waste (MSW). However, many countries seek to implement different methods of MSW treatment due to the high global warming potential associated with landfilling. Other methods such as recycling and incineration are either limited to only a fraction of generated MSW or still produce large greenhouse gas emissions, thereby providing an unsustainable disposal method. Here, the production of graphene from treated MSW is reported that including treated wood waste, using flash Joule heating. Results indicated a 71%-83% reduction in global warming potential compared to traditional disposal methods at a net cost of -$282 of MSW, presuming the graphene is sold at just 5% of its current market value to offset the cost of the flash Joule heating process.

Fate of sulfur and chlorine during co-incineration of municipal solid waste and industrial organic solid waste

In China, the co-incineration of municipal solid waste (MSW) with industrial organic solid waste (IOSW) is increasingly adopted. Compared with MSW, IOSW contains higher levels of sulfur (S) and chlorine (Cl), presenting significant challenges for controlling S/Cl emissions in MSW incineration plants. In this study, the impact of co-incinerating IOSW was investigated in a 500 t/d incinerator grate, focusing on the emissions and transformation behaviors of S/Cl. IOSW, with a consistent sulfur content of about 0.22 wt% and a more variable chlorine content averaging 0.53 wt%, contains over 40 % organic sulfur and >90 % organic chlorine, higher than in MSW. The results of co-incineration experiments showed that the median SO2 concentration in the flue gas was stable at 50 mg/m3, while HCl concentration decreased initially and then increased as the co-incineration ratio of IOSW rose from 20 % to 40 %. Furthermore, the concentrations of SO2 and HCl were not significantly influenced by wind flow but were positively affected by the rising furnace temperatures. Besides, the co-incineration ratio had minimal impact on sulfur in fly ash before deacidification, primarily derived from the gas stream. However, the (Na + K)/Cl ratio in fly ash progressively increased from 1.5 to 1.9, and the Ca content decreased from 0.35 % to 0.15 % as the co-incineration ratio rose to 40 %, indicating more chlorine migration into the fly ash at higher co-incineration rates. This research offers essential guidance for effectively controlling pollutant emissions during the co-incineration of IOSW, specifically the S/Cl pollutants.

Synergistic control potential of flue gas pollutants under Ultra-Low emission standards in waste incineration plants

As the dominant waste disposal process, incineration is regarded as the main incentive for the "not-in-my-backyard" syndrome, and faces an inescapable pressures of ultra-low emissions (ULE). Establishing precise response relationships between emission factors (EFs) and full-process influencing factors can provide guidance for the synergistic mitigation of flue gas pollutants (FGPs). In this work, the multi-dimensional EFs of FGPs were identified by initially integrating FGPs concentration monitoring data of existing 1,226 processing lines in China, technologies applied and operational experience (OE), local economic and political characteristics. Significant regional imbalance performance was observed, which EFs in the coastal regions were 3.55-92.39 % lower than those of the inland areas. NOx, SO2, HCl were identified as critical components requiring further reduction under the ULE standards, with exceedance rates recorded at 73.07 %, 38.90 %, and 56.69 %, respectively. An indicative value of 20 mg/m3 for PM is recommended for the control of heavy metals of Cd + Tl and Sb + As + Pb + Cr + Co + Cu + Mn + Ni based on the correlation coefficients of r = 0.28 (p < 0.001) and r = 0.20 (p = 0.002), respectively. Waste composition and OE were quantified as the main contributors of EFs' disparities by the tree-branching controlled variable approach established in this study. Predictive models for FGPs control process and corresponding EFs were constructed. EFs of nine FGPs in 2030 would decrease by 0.97-65.42 %, due to more complex purification processes employed to meet ULE's limitations, such as the application of five-stage processes growing from 45.60 % to 58.28 %. While regional imbalance in EFs-SO2 and EFs-HCl were extended with increases from 25.83 % to 33.07 % and 9.91 % to 32.32 %, respectively, due to the consistent disparities of OE and growing heterogeneity of control policies. Enhancing interregional empirical exchanges, reducing the regional market monopolies, and formulating technical guidelines would be beneficial to synergize the reduction of FGPs emissions and alleviate regional imbalance.

Response of trace elements in urban deposition to emissions in a northwestern river valley type city: 2010-2021

Anthropogenic activities release significant quantities of trace elements into the atmosphere, which can infiltrate ecosystems through both wet and dry deposition, resulting in ecological harm. Although the current study focuses on the emission inventory and deposition of trace elements, their complex interactions remain insufficiently explored. In this study, we employ emission inventories and deposition data for eight TEs (Cr, Mn, Ni, Cu, Zn, As, Cd, Pb) in Lanzhou City to unveil the relationship between these two aspects. Emissions in Lanzhou can be roughly divided into two periods centered around 2017. Preceding 2017, industrial production constituted the primary source of TEs emissions except for As; coal combustion was the primary contributor to Cr, Mn, and As emissions; waste incineration played a significant role in As, Zn, and Cd emissions; biomass combustion influenced Cr and Cd emissions; and transportation sources were the predominant contributors to Pb and Cu emissions. With the establishment of waste-to-energy plants and the implementation of ultra-low emission retrofits, emissions from these sources decreased substantially after 2017. Consequently, emissions from industrial production emerged as the main source of TEs. The deposition concentrations of Cr, Mn, Ni, Cu, and Pb followed a similar trend to the emissions. However, Cd and As exhibited lower emissions and a less pronounced response relationship. Moreover, Zn concentrations fluctuated within a narrow range and showed a weaker response to emissions. The consistent changes in emissions and TEs deposition concentrations signify a shift in deposition pollution in Lanzhou city from Coal-fired pollution to that driven by transportation and industrial activities. Within this transition, the industrial production process offers significant potential for emission reduction. This insight provides a crucial foundation for managing TEs pollution and implementing strategies to prevent ecological risks.

Comparing and optimizing municipal solid waste (MSW) management focused on air pollution reduction from MSW incineration in China

China is the largest developing country in the world, and its municipal solid waste (MSW) has increased with a compound annual growth rate of 5.1 % since 1980. Incineration, which has the advantages of mass- and volume-reduction as well as energy and heat recovery, has become the mainstream environmentally sound treatment method in China. However, air pollution emissions are the primary reason for limiting MSW incineration (MSWI). Currently, the Chinese government is devoted to comprehensively implementing MSW classification. However, the classification model and the future MSW reduction rate are not yet clear. In this study, we project scenarios of air pollution emissions until 2030 based on the different MSW classification models (MSW reduction rates) and diffusion rates of ultra-low emission technology. A total of 6011 tons (t) of particulate matter, 25,881 t of SO2, 14,915 t of CO, 17,167 t of HCl, and 200,166 t of NOx will be emitted in 2030 under the business-as-usual (BAU) scenario, and air pollutants will not peak under this scenario. Air pollutants will reduce by 11 % of the BAU scenario by only implementing an MSW reduction of 20 % (JPN-model). The optimal scenario (DEU-model, increasing the efficiency of material recovery and upgrading air pollution control devices) means that air pollutants will be reduced by 83.2-96.2 % from the base amount under the BAU scenario. These results provide references for MSW management and air pollution emission reduction from the aspects of MSW classification and technology upgrades in China.

Health effects of future dioxins emission mitigation from Chinese municipal solid waste incinerators

Dioxins (including 2,3,7,8-tetrachlorodibenzo-p-dioxin, as Group 1 Carcinogen) in the atmosphere mainly originate from incomplete combustion during municipal solid waste (MSW) incineration. To significantly reduce dioxins emission from the MSW incineration industry, China has promulgated a set of ambitious plans regulating MSW-related pollution; however, the emission reduction potentials and concomitant environmental and health impacts associated with the implementation of these programs on a national scale remain unknown. Here, we use real measurements from official environmental impact assessment systems and continuous emissions monitoring systems (covering 96.6% of national MSW incinerators) to estimate unit-level dioxins emission and concomitant environmental and health impacts. We find that in 2018, 99.3% and 66.7% of Chinese incinerators met such concentration and temperature standards, respectively, controlling the total emissions to 19.6 g toxic equivalency quantity and maintaining carcinogenic and noncarcinogenic risks significantly below safety levels nationwide. Fully achieving both current standards and future regulations will reduce emissions and health risks by 67.7% and 62.6%, respectively, with waste sorting program contributing the majority. This study reveals substantial benefits from curbing MSW-related dioxins pollution and underscores the promise of ongoing management.

Effecting pattern study of SO2 on Hg0 removal over α-MnO2 in-situ supported magnetic composite

α-MnO₂ was in-situ supported onto silica coated magnetite nanoparticles (MagS-Mn) to study the adsorption and oxidation of Hg⁰ as well as the effecting patterns of SO₂ and O₂ on Hg⁰ removal. MagS-Mn showed Hg⁰ removal capacity of 1122.6 μg/g at 150 °C with the presence of SO₂. Hg⁰ adsorption and oxidation efficiencies were 2.4% and 90.6%, respectively. Hg⁰ removal capability deteriorated at elevated temperatures. Surface oxygen and manganese chemistry analysis indicated that SO₂ inhibited the Hg⁰ removal through consumption of adsorbed oxygen and reduction of high valence manganese. This inhibiting effect was observed to be counteracted by O₂ at lower temperatures. O₂ tended to compete with SO₂ for active sites and further create additional adsorbed oxygen sites for Hg⁰ surface reaction via surface dissociative adsorption rather than replenish the active sites consumed by SO₂. The high valence manganese was also preserved by O₂ which was essential to Hg⁰ oxidation. The intervention of O₂ in the inhibition of SO₂ on Hg⁰ removal was weakened at temperatures higher than 250 °C. Aa a result, Hg⁰ tends to be catalytic oxidized in the condition of low reaction temperatures and with the presence of O₂ over α-MnO₂ oriented composites.

Ecotoxicity of PM10 emissions generated during controlled burning of waste PET

Domestic waste is often burned either as fuel for winter heating or in open areas, simply to get rid of waste. Polyethylene terephthalate (PET) represents an important component of plastics usage as well as of plastic waste produced. While most studies attempt to characterize environmental risk of open burning of mixed household waste, present work evaluates chemical and ecotoxicological parameters of particulate matter (PM) produced during controlled burning of PET samples. In the PM₁₀ samples, polycyclic aromatic hydrocarbon and heavy metal concentrations were measured, ecotoxicity was evaluated using the kinetic Vibrio fischeri bioassay. Both chemical composition and ecotoxicity of the 4 samples showed significant correlation, regardless of the colored or colorless nature of the original PET sample. Antimony was found in considerable concentrations, in the range of 6.93-16.9 mg/kg. PAHs profiles of the samples were very similar, showing the dominance of 4-and 5-ring PAHs, including carcinogenic benzo(a)pyrene.

PCDD/Fs in indoor environments of residential communities around a municipal solid waste incineration plant in East China: Occurrence, sources, and cancer risks

Prolonged exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) can pose several adverse outcomes on human health. However, there is limited information on public health associated with indoor PCDD/F exposure in residential environments. Here, we examined PCDD/F concentrations in indoor air and indoor dust samples obtained from households near a municipal solid waste incineration (MSWI) plant. Our measurements revealed that the toxic equivalent (TEQ) concentrations of PCDD/Fs in indoor air ranged from 0.01 to 0.05 pg TEQ/m³, which were below intervention thresholds (0.6 pg TEQ/m³). Additionally, the TEQ concentrations of PCDD/Fs in indoor dust ranged from 0.30 to 11.56 ng TEQ/kg. Higher PCDD/F levels were found in household dust in the town of Taopu compared to those in the town of Changzheng. Principal component analysis (PCA) of PCDD/Fs suggested that waste incineration was the primary source of PCDD/Fs in indoor air, whereas PCDD/Fs in indoor dust came from multiple sources. The results of the health risk assessment showed the carcinogenic risk due to indoor PCDD/F exposure was higher for adults than for nursery children and primary school children. The carcinogenic risks of PCDD/Fs for age groups residing near the MSWI plant were all less than the risk threshold (10^-5). Our findings will help to better understand the levels of PCDD/F exposure among urban populations living in residential communities around the MSWI plant and to formulate corresponding control measures to reduce probabilistic risk implications.

Air pollutant emissions and reduction potentials from municipal solid waste incineration in China

China fully implemented the new emission standards in 2016 to further reduce the emissions of air pollutants from the municipal solid waste (MSW) incineration industry; however, the implementation effect of the new standards remains unknown. This study developed the first nationwide air pollutant emission inventory of MSW incineration plants in China based on the measured concentration data from China's continuous emissions monitoring systems (CEMS) network, and activity level data from the China Urban Construction Statistical Yearbook, to evaluate the effectiveness of implementing the new emission standards and estimate the future reduction potentials. Our results demonstrated that the overall standard-reaching proportions of particulate matter (PM), sulfur dioxide (SO₂), nitrogen oxide (NO_X), hydrogen chloride (HCl) and carbon monoxide (CO) were 98.8%, 99.3%, 99.4%, 99.4% and 97.6%, respectively, by comparing with the corresponding concentration limits of new emission standards. The total emissions of PM, SO₂, NO_X, HCl and CO from 412 MSW incineration plants in 2019 were 1.9, 6.2, 50.8, 4.3 and 6.6 kt yr^-1, respectively, which is 33.6-75.8% lower than those in 2015, mainly due to the sharp decrease in emission factors. Pollutant emission hotspots were mainly concentrated in eastern and central and southern regions with large populations and well-developed economies. The analysis of future scenario results shows that despite the continuous increase of MSW incineration amount in the future, if the government strengthens pollutant emission standards and comprehensively implements waste sorting, total emissions and emission factors of air pollutants could be further reduced by 25.8-72.7% and 59.8-81.2%, respectively, by 2050. These findings provide helpful insights into future policymaking and technology selection for China and other countries seeking to reduce pollutant emissions from the MSW incineration industry.

Present Knowledge and Future Perspectives of Atmospheric Emission Inventories of Toxic Trace Elements: A Critical Review

Toxic trace elements (TEs) can pose serious risks to ecosystems and human health. However, a comprehensive understanding of atmospheric emission inventories for several concerning TEs has not yet been developed. In this study, we systematically reviewed the status and progress of existing research in developing atmospheric emission inventories of TEs focusing on global, regional, and sectoral scales. Multiple studies have strengthened our understanding of the global emission of TEs, despite attention being mainly focused on Hg and source classification in different studies showing large discrepancies. In contrast to those of developed countries and regions, the officially published emission inventory is still lacking in developing countries, despite the fact that studies on evaluating the emissions of TEs on a national scale or one specific source category have been numerous in recent years. Additionally, emissions of TEs emitted from waste incineration and traffic-related sources have produced growing concern with worldwide rapid urbanization. Although several studies attempt to estimate the emissions of TEs based on PM emissions and its source-specific chemical profiles, the emission factor approach is still the universal method. We call for more extensive and in-depth studies to establish a precise localization national emission inventory of TEs based on adequate field measurements and comprehensive investigation to reduce uncertainty.

Air Pollutant Emission Inventory of Waste-to-Energy Plants in China and Prediction by the Artificial Neural Network Approach

The waste-to-energy (WTE) plant has been deployed in 205 cities in China. However, it always faces public resistance to be built because of the great concerns on flue gas pollutants (FGPs). There are limited studies on the socioeconomic heterogeneity analysis and prediction models of WTE capacity/ FGP emission inventories (EIs) based on big data. In this study, the incinerator level emission factors (EFs) in 2020 of PM, SO₂, NO_x, CO, HCl, dioxins, Hg, Cd + Tl, and Sb + As+ Pb + Cr + Co + Cu + Mn + Ni were calculated based on 322,926 monitoring values of all the 481 WTE plants (1140 processing lines) operating in China, with uncertainties in the range of ±34.70%. The EFs were significantly 45-96% lower than the national standard (GB18485-2014) and had negative relationships with local socioeconomic elements, while WTE capacity and FGP EIs had significantly positive correlations. Gross domestic product, area of built district, and municipal solid waste generation were the main driving forces of WTE capacity. The WTE capacity increased by 150% from 2015 to 2020, while the total emission of PM, SO₂, CO, dioxins, Hg, and Sb + As + Pb + Cr + Co + Cu + Mn + Ni decreased by 42.46-88.24%. The artificial neural network models were established to predict WTE capacity and FGP EIs in the city level, with the mean square errors ranging from 0.003 to 0.19 within the model validation limits. This study provides data and model support for the formulation of appropriate WTE plans and a pollutant emission control scheme in different economic regions.

Spatiotemporal characteristics of air pollution in Chengdu-Chongqing urban agglomeration (CCUA) in Southwest, China: 2015-2021

Studying the spatiotemporal characteristics of air pollutants in urban agglomerations and their response factors will help to improve the quality of urban living. In combining air quality monitoring data and wavelet analysis from the Chengdu-Chongqing urban agglomeration (CCUA), this study assessed the spatiotemporal distribution characteristics and influential factors of air pollutants on daily, monthly and annual scales. The results showed that the concentration of air pollutants in the CCUA has decreased year by year, and air quality has improved. Except for O₃, pollutants in autumn and winter were higher than those in summer. The spatial distribution of air pollutants was obvious distributed in Chengdu, Chongqing, Zigong and Dazhou. Pollution incidents were mainly concentrated in winter. The 6 air pollutants and air quality index (AQI) have dominant periods on multiple time scales. AQI showed positive coherence with PM_2.5 and PM₁₀ on multiple time scales, and obvious positive coherence with SO₂, CO, NO₂ and O₃ in the short term scale. AQI was not strongly correlated with the fire point, but exhibited obvious negative coherence in the long term scale. In addition, AQI showed an obvious positive correlation with temperature and sunshine hours in short term, and a clear negative correlation with humidity and rainfall. The research results of this paper will provide a reference for pollution prevention and control in the CCUA.

National and provincial dioxin emissions from municipal solid waste incineration in China

China presently lacks an up-to-date regional inventory of dioxin emissions from municipal solid waste incineration (MSWI), although MSWI has grown rapidly in recent decades. Based on dioxin concentrations from the official website for governments and enterprises, we created an inventory of dioxin emissions from 29 areas in mainland China. MSWI released a total of 22.56 g I-TEQ of dioxins in 2020. According to Monte Carlo simulation, the dioxin emissions with 95 %, 75 %, and 50 % certainty are 17.03-31.62, 19.24-27.71, and 20.43-25.96 g I-TEQ, respectively. Notably, Guangdong, Zhejiang, and Jiangsu provinces accounted for 38.8 %. The primary regions with considerable dioxin emission per capita and density are Zhejiang and Shanghai. Furthermore, Jilin and Heilongjiang provinces are the top two regions in terms of dioxin emissions per unit of billion gross domestic product. These indicators were affected significantly by the quantity of MSW generated and incinerated (MSWGI), capacity and operating years of incinerators, and degrees of air pollution control devices (APCDs). Dioxin emission factors (EFs) were about 100 times lower in 2020 than in 2004. Note, however, that there is a gap in dioxin EFs between China and European nations. We have proposed that MSW source classification, stable operation conditions of incinerators and APCDs, categories of incinerators selection, and technological upgrading should be China's major measures to curb dioxin emissions. Moreover, with the future increment in the quantity of MSWGI, it is essential to completely reinvent the dioxin monitoring program.

A Review of the Impact That Healthcare Risk Waste Treatment Technologies Have on the Environment

Health-Care Risk Waste (HCRW) treatment protects the environment and lives. HCRW is waste from patient diagnostics, immunization, surgery, and therapy. HCRW must be treated before disposal since it pollutes, spreads illnesses, and causes harm. However, waste treatment increases the healthcare sector's carbon footprint, making the healthcare sector a major contributor to anthropogenic climate change. This is because treating HCRW pollutes the environment and requires a lot of energy. Treating HCRW is crucial, but its risks are not well-studied. Unintentionally, treating HCRW leads to climate change. Due to frequent climate-related disasters, present climate-change mitigation strategies are insufficient. All sectors, including healthcare, must act to mitigate and prevent future harms. Healthcare can reduce its carbon footprint to help the environment. All contributing elements must be investigated because healthcare facilities contribute to climate change. We start by evaluating the environmental impact of different HCRW treatment technologies and suggesting strategies to make treatments more sustainable, cost-effective, and reliable to lower the carbon footprint.

Curbing dioxin emissions from municipal solid waste incineration: China's action and global share

China generates the world's second-largest amount of municipal solid waste (MSW) and incinerates the largest quantity of MSW. However, data on the latest dioxin emissions from MSW incineration (MSWI) and the related global share were lacking. In the context of MSW classification, distinguishing the long-term MSW generation and incineration quantity, and dioxin emissions was necessary for macro-control and policy-making by the Chinese Government. By considering population size and GDP per capita, China's MSW generation toward 2050 was projected based on Monte Carlo simulation. Moreover, dioxin emission factors were also assumed based on the diffusion rate of four grades of air pollution control devices (APCDs). Finally, we show that the quantity of China's MSW generation in 2050 will be 363.50 million tonnes (Mt) with 341.06-382.45 Mt of 75% certainty. China's dioxin emissions from MSWI were approximately 15.46 g I-TEQ in 2019, which accounted for 26.1% of total emissions from global MSWI. We discuss dioxin emission reduction scenarios depending on MSW diversion and APCD upgrades. China's dioxin emissions will be 70.38 g I-TEQ for the business-as-usual scenario, and the dioxin emissions will be 9.29 g I-TEQ (within the range of 8.88-9.64 g I-TEQ) for the optimal scenario in 2050. Moreover, in 2050, the APCD diffusion rate will account for 98.8% of the sensitivity of dioxin emissions from China's MSWI. According to the assumed scenarios, there is a dioxin emission reduction potential of 18.6% and 86.8% in 2050 by MSW diversion alone and maximum APCD upgrades combined with food waste diversion, respectively.