Particulate Matter Emissions Research Articles

Particulate emissions from biomass power plants: a practical review and measurement uncertainty issues

This paper follows a practical approach to evaluate particulate matter emissions from biomass-fuelled power plants and analysis measurement uncertainties. Sixty-seven measurement reports from 11 biomass power plants, all equipped with fabric filters as dust control device, were analysed. Particulate matter emission measurements by gravimetrical standard reference method were chosen to provide the most reliable values to investigate the influence of bag filter parameters, such as media age or bag filter length. 92.1% of total dust emission measurements were below lower BAT-associated emission levels (BAT-AELs) for waste incineration. Data also showed that bag filter media older than 6 years can still secure very low dust emission levels. This work also gives a summary of findings and problems with uncertainty of automated measuring systems for dust emissions in biomass combustion applications in practice and quality assurance level one (QAL1) process related to very low emission levels such as lower best available techniques reference document (BREF) values. Practical examples on issues of continuous dust emission monitoring devices are also given.

An Integrated Analysis on the Synergistic Reduction of Carbon and Pollution Emissions from China’s Iron and Steel Industry

Decarbonization and decontamination of the iron and steel industry (ISI), which contributes up to 15% to anthropogenic CO2 emissions (or carbon emissions) and significant proportions of air and water pollutant emissions in China, are challenged by the huge demand for steel. Carbon and pollutants often share common emission sources, indicating that emission reduction could be achieved synergistically. Here, we explored the inherent potential of measures to adjust feedstock composition and technological structure and to control the size of the ISI to achieve carbon emission reduction (CER) and pollution emission reduction (PER). We investigated five typical pollutants in this study, namely, petroleum hydrocarbon pollutants and chemical oxygen demand in wastewater, particulate matter, SO2, and NOx in off gases, and examined synergies between CER and PER by employing cross elasticity for the period between 2022 and 2035. The results suggest that a reduction of 8.7%–11.7% in carbon emissions and 20%–31% in pollution emissions (except for particulate matter emissions) could be achieved by 2025 under a high steel scrap ratio (SSR) scenario. Here, the SSR and electric arc furnace (EAF) ratio serve critical roles in enhancing synergies between CER and PER (which vary with the type of pollutant). However, subject to a limited volume of steel scrap, a focused increase in the EAF ratio with neglection of the available supply of steel scrap to EAF facilities would lead to an increase carbon and pollution emissions. Although CER can be achieved through SSR and EAF ratio optimization, only when the crude steel production growth rate remains below 2.2% can these optimization measures maintain the emissions in 2030 at a similar level to that in 2021. Therefore, the synergistic effects between PER and CER should be considered when formulating a development route for the ISI in the future.

Contribution of fossil and biomass-derived secondary organic carbon to winter water-soluble organic aerosols in Delhi, India

Delhi, among the world's most polluted megacities, is a hotspot of particulate matter emissions, with high contribution from organic aerosol (OA), affecting health and climate in the entire northern India. While the primary organic aerosol (POA) sources can be effectively identified, an incomplete source apportionment of secondary organic aerosol (SOA) causes significant ambiguity in the management of air quality and the assessment of climate change. Present study uses positive matrix factorization analysis on the water-soluble organic aerosol (WSOA) data from the offline-aerosol mass spectrometry (AMS). It revealed POA as the dominant source of WSOA, with biomass-burning OA (31–34 %) and solid fuel combustion OA (∼21 %) being two major contributors. Here we use water-solubility fingerprints to track the SOA precursors, such as oxalates or organic nitrates, instead of identifying them based on their O:C ratio. Non-fossil precursors dominate in more oxidized oxygenated organic carbon (MO-OOC) (∼90 %), a proxy for aged secondary organic carbon (SOC), by coupling offline-AMS with 14C measurements. On the contrary, the oxidation of fossil fuel emissions produces a large quantity of fresh fossil SOC, which accounts for ∼75 % of less oxidized oxygenated organic carbon (LO-OOC). Our study reveals that apart from major POA contributions, large fractions of fossil (10–14 %) and biomass-derived SOA (23–30 %) contribute significantly to the total WSOA load, having impact on climate and air quality of the Delhi megacity. Our study reveals that large-scale unregulated biomass burning was not only found to dominate in POA but was also observed to be a significant contributor to SOA with implications on human health, highlighting the need for effective control strategies.

Effect of ferrocene as a combustion catalyst on the premixed combustion flame characteristics of Jatropha biodiesel

Fuel additives are widely used to optimize the combustion process, reduce the harmful emissions, and improve the performance of engines. Among the metal-based additives, ferrocene is soluble in most fuels, including biodiesel. Furthermore, it is easily available and has high stability, low toxicity, and high lipophilicity. It can evenly disperse in biodiesel without causing any change in the physicochemical properties. Therefore, it can serve as an effective combustion catalyst for biodiesel. In this study, the effect of ferrocene as a combustion catalyst on the pyrolysis and combustion performance of Jatropha biodiesel is investigated. The coupled technique of thermogravimetry-Fourier transform infrared spectroscopy-mass spectrometry (TG-FTIR-MS) is used to analyze the evolution characteristics of multicomponent gaseous products generated during the pyrolysis and high-temperature oxidation of Jatropha biodiesel (JB100) and Jatropha biodiesel + ferrocene (JBF). The laminar premixed combustion flame and pollutant emissions of JB100 and JBF are examined using a variety of techniques, including OH planar laser-induced fluorescence (OH-PLIF), flue gas analysis, spectral analysis, transmission electron microscopy, etc. The results reveal that after adding ferrocene, the activation energy for the pyrolysis reaction of JB100 decreases by 4.66 kJ/mol and the complete weight loss temperature decreases by 10 ℃. Further, the addition of ferrocene reduces the endothermic heat by 0.38 mW/mg during the initial stage of the high-temperature oxidation reaction of JB100, and the amounts of final products CO2 and H2O are increased. Compared with JB100, JBF shows an enhanced OH group intensity in the combustion flame and a lower soot spectral peak. Furthermore, compared with JB100, under JBF combustion, the pollutant PM2.5 emissions decrease by 13.3 %, PM10 emissions decrease by 13.2 %, PM> 10 particulate matter emissions decrease by 19.3 %, CO emissions decrease by 6.8 %, NOx emissions increase by 21.2 %, and the size of soot particles decreases by 20.8 %.

Effect of operation conditions on particulate matter removal by a packed-bed wet scrubber for a small-scale biofuel boiler

In 2013 the EU’s Clean Air Policy Package was established, aiming to reduce air pollution to half by 2030 compared to the level in 2005. Small-scale (<500 kW)biofuel boilers play a key role in particulate matter emission, and exposure to particulate matter even in the short term can cause different diseases. With the aim of reducing particulate matter emission in Europe, this study presents an approach to improve the removal of particulate matter emitted by small-scale boilers. A biofuel combustion boiler was equipped with a packed-bed wet scrubber, and the flue gas emitted through combustion was cleaned through the wet scrubber using a saltwater mixture. The performance of a packed-bed wet scrubber was investigated under different operating conditions. The effect of the salt concentration of the absorption solution, the temperature of the absorption solution fed to the absorber, and the height of the packed-bed material on the particle collection efficiency were measured. The operating conditions were selected based on the results obtained in a previous computational fluid dynamic simulation study. The results obtained in the present study show that an absorption solution temperature of 30 °C and an absorption solution concentration of 75 % with a full height of the packed-bed material lead to the best performance in the system. Totally keeping the absorption solution temperature as low as possible, increasing the absorption solution concentration, and raising the packed-bed material height could improve the particle collection efficiency by enhancing the effect of the diffusiophoresis and thermophoresis forces and the contact time between the flue gas and solution.

USEPA CALPUFF validation and dispersion modeling of beef cattle feedlot PM10 and PM2.5 emissions factors

Beef cattle feedlots are major sources of criteria air pollutants in the United States. To aid stakeholders in air quality modeling, emissions factors for animal waste-producing facilities are under development by the U.S. Environmental Protection Agency (USEPA). However, beef cattle feeding operations (feedlots) are not among facilities surveyed under the associated USEPA National Air Emissions Monitoring Study (NAEMS). Authors aim to supplement NAEMS through development and validation of particulate matter (PM10 and PM2.5) emission factors from a previous sampling campaign of five large feedlots in the Southern High Plains of North America via USEPA's CALPUFF dispersion model. PM concentrations were higher overall during the warm season (March–August; PM10 = 692 ± 507, PM2.5 = 114 ± 110 μg/m3) relative to cool season (November–January; PM10 = 102 ± 105, PM2.5 = 12.2 ± 8.6 μg/m3), and overall median PM10 and PM2.5 emission factors were 48.2 (day = 33.8, night = 72.4) and 5.22 (day = 8.4, night = 3.1) mg/m2/hr, respectively. Validated emissions factors were then used to model diurnal peaks and long-range transport (100 km maximum extent). Peak concentrations were most frequently observed between 2000 and 0600 h (93.9%; mean 1-hr peak ± SD = 1119 ± 1240 μg/m3) for PM10 and 1600-0600 h (80.0%; mean 1-hr peak ± SD; 178 ± 174 μg/m3) for PM2.5. Four of five feedlots exceeded ≥1 primary PM National Ambient Air Quality Standard (NAAQS) at receptors (2-m height) over a 5-km spatial extent during the modeling period (November 2010–August 2011). Moreover, present estimates of feedlot-derived inhalable PM represent human and environmental exposure pathways currently exempt from Clean Air Act monitoring and reporting standards, and spatial interpolation of federal air quality monitors cannot adequately characterize inhalable PM concentrations in non-metropolitan municipalities and unincorporated rural communities.

Particulate Pb emission factors from wildland fires in the United States

Wildland fires, which includes both wild and prescribed fires, and agricultural fires in sum are one of the largest sources of fine particulate matter (PM2.5) emissions to the atmosphere in the United States (US). Although wildland fire PM2.5 emissions are primarily composed of carbonaceous material, many other elements including trace metals are emitted at very low levels. Lead (Pb) is a US Environmental Protection Agency (EPA) criteria pollutant that is ubiquitous in the environment at very low concentrations including in biomass that can burn and emit Pb into the atmosphere. Although fires may emit Pb at very low concentrations, they can be a source of sizeable Pb emissions to the atmosphere because of the large quantity of PM2.5 emitted from fires. In this work, we measure Pb concentrations in unburned biomass, ash/residues, and particulate matter <2.5 μm (PM2.5) emitted from wildland fires using in-field measurements near prescribed fires and in laboratory simulations. Emission factors were calculated for multiple biomass types, representative of different regions of the US including grasslands in Oregon and Kansas; forest litter from Oregon, Montana, Minnesota, and North Carolina; and peat cores from Minnesota. Most of the biomass Pb remains in the ash/residues. The small percentage (<10%) that is emitted in PM2.5 is dependent on the biomass Pb concentration. The emissions factors measured here are several orders of magnitude lower than some reported in the literature, but the studies exhibited a wide range of values, which may be due to large uncertainties in the measurement method rather than differences in Pb emissions. Wildland fires are expected to increase in size and frequency in future years and these new emission factors can be used to improve the accuracy of Pb emissions estimates and better constrain our understanding of Pb emissions to the atmosphere.

Multi-objective impact mechanism on the performance characteristic for a diesel particulate filter by RF-NSGA III-TOPSIS during soot loading

Diesel particulate filter (DPF) provides an effective control method for particulate matter (PM) emissions from diesel vehicles. In the PM trap process of DPF, pressure drop and filtration efficiency present conflicting relationships as the main indicators of the comprehensive trap performance. To fully optimize the comprehensive trap performance of DPF, this research develops a hybrid multi-objective optimization approach of FGRA-RF-NSGA III-TOPSIS. Specifically, critical structures are selected from DPF structural features by fuzzy grey correlation analysis (FGRA). Three machine learning (ML) models are trained on the computational fluid dynamics (CFD) model dataset to relate the critical structures to the initial filtration efficiency and pressure drop. Then, statistical indicators are introduced to evaluate three ML models, and the best-performing model – The random forest (RF) model is selected as the input of the optimization algorithm. Finally, a hybrid Critic-TOPSIS approach is used to select the most ideal solution from the Pareto frontier obtained by the NSGA III as the output of the optimization results. The optimized DPF reduces the pressure drop by 49.84 % and improves the initial filtration efficiency by 49.31 % compared to the original DPF under standard operating conditions. The optimization effect is more significant at high-speed and high-load conditions.

Effect of phospholipids on the oxidative reactivity and microstructure of soot particles from Jatropha biodiesel combustion

Excessive phosphorus content can aggravate the formation and emission of particulate matter (PM) during biodiesel combustion, which can lead to the performance degradation of automobile exhaust catalytic converters and make it difficult to control pollutant emissions. However, the influential mechanism of phosphorus in biodiesel on PM formation is not clear yet. Therefore, thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy are used to study the formation, oxidation characteristics, and nanostructures of soot particles produced from Jatropha biodiesel (JB100) combustion under different phospholipid (PE:phosphatidylethanolamine, main phospholipid type in JB100) contents. The results show that with increasing PE content in JB100, the amount of soot particles first increases and then decreases. When the PE content is 400 ppm, the amount of soot particles is the largest, almost 13.40% higher than that produced from neat JB100. Further, the activation energy (AE) of soot oxidation first increases and then decreases with increasing PE content. The apparent AE is the largest (131.40 kJ/mol) at 400 ppm. Furthermore, when the PE content is 400 ppm, the strength of oxygen-containing functional groups in the soot particles is the weakest, and the ratio of nanocrystal height to polycyclic aromatic hydrocarbons (PAHs) interlayer spacing (Lc/d002) (4.396), the average lattice spacing of PAHs (0.367 nm), and the ratio of D1 and G peaks integral intensity (ID1/IG) (2.566) are minimum. This verifies that the PE content in JB100 can affect the strength of active oxygen-containing functional groups and the size and structure of PAHs in the soot particles and that the oxidative reactivity of soot particles is lowest at 400 ppm.

Emissions and combustion characteristics of torrefied wood pellets

The influence of torrefaction temperature on the durability, combustion characteristics, and emissions of CO, CO2, NOX, and particulate matter (PM) from biomass pellets was studied. The pellets were torrefied under inert conditions at 225, 250, and 300 °C for 60 min. Physical properties, such as weight loss, fines percentage, pellet durability index (PDI), and water absorption, were evaluated using ISO standards. The weight loss increased with higher torrefaction temperatures. Torrefied pellets had lower water absorption than untreated pellets. Fines percentage increased with torrefaction temperature while PDI decreased. Torrefied pellets at 300 °C had the lowest PDI (82.7%), while 225 °C had the highest (98.0%). The energy density and heating values increased with torrefaction temperature from 22.0 MJ/kg at 225 °C to 29.9 MJ/kg at 300 °C compared to 18.9 MJ/kg for untorrefied pellets. There were reductions in CO, CO2, and NOX emissions with an increase in torrefaction temperature while PM slightly reduced. This study found that torrefied biomass pellets had lower CO2 emissions than raw pellets.

Particulate Matter and Volatile Organic Compound Emissions Generated from a Domestic Air Fryer.

Air frying has become a popular cooking method for domestic cooking, but the level of released indoor air pollutants is poorly understood. In this work, we compared particle and gas phase emission factors (EF) and particle size distributions between cooking with a domestic air fryer and a pan for a variety of foods. The PM10 EFs of air frying chicken wings and breast were higher than pan cooking by a factor of 2.1 and 5.4, respectively. On the other hand, a higher PM10 emission factor from air frying can be achieved by increasing the amount of oil to levels similar to or above those from pan-frying for French fries and asparagus. We propose that higher temperature and greater turbulence lead to higher PM10 EFs for cooking with the air fryer compared with the pan for the same mass of oil added. EFs of volatile organic compounds (VOCs) are also generally higher for cooking with the air fryer compared with the pan: 2.5 times higher for French fries and 4.8 times higher for chicken breast. Our study highlights the potential risk of higher indoor PM10 levels associated with domestic air frying under certain cases and proposes possible mitigation measures.

Gaseous, particulate matter, carbonaceous compound, water-soluble ion, and trace metal emissions measured from 2019 peatland fires in Palangka Raya, Central Kalimantan

This study aimed to develop field emission factors of gaseous pollutants, PM2.5, OC/EC, water-soluble ions, and trace elements and to estimate the total gas and particulate emissions from peatland fires. This study was conducted in Palangka Raya, Central Kalimantan, in September 2019 during the main fire episode. Gas samples were collected using the LGR-ICOS analyzer at a flow rate of 0.5 L/min. In comparison, particulate pollutant samples were collected using two Airmetrics Mini Volume Portable Air Samplers at a flow rate of 5 L/min with Quartz fiber and PTFE filters. For further analysis, quartz fiber filters were used for carbon aerosols and water-soluble inorganic ions, while PTFE filters were used for trace element analysis. The gaseous emission factors determined in this study for CO2, CO, and CH4 were 1589.5 ± 41.8 g/kg, 236.5 ± 25.7 g/kg, and 5.4 ± 1.3 g/kg, respectively. Meanwhile, the emission factors for PM2.5, OC, EC, water-soluble inorganic ions, and elements were 27.8 ± 41.8 g/kg, 18.1 ± 8.9 g/kg, 0.25 ± 0.06 g/kg, 1.7 ± 0.7 g/kg, and 62.5 ± 32.3 mg/kg, respectively. With peat burned density of 0.11 g/cm3, a burned depth of 37 cm, and a total area burned of 317,749 ha, peatland fires in Central Kalimantan in 2019 had emitted CO2, CO, PM2.5, total carbon aerosol, water-soluble ions, and elements about 34.9 ± 0.9 Tg, 5.3 ± 0.6 Tg, 0.6 ± 0.3 Tg, 0.4 ± 0.2 Tg, 36.7 ± 15.9 Gg, and 1.4 ± 0.7 Gg, respectively.

Microstructure and Wear Resistance of Fe3Al Coating on Grey Cast Iron Prepared via Direct Energy Deposition

In this study, the potential of Fe3Al coating material as an environmentally friendly alternative to coatings containing critical elements for brake discs was investigated. A buffer layer of Cr–Mo steel (Ferro 55) that was about 500 µm thick was applied on a gray cast iron disc to enhance the coating quality and prevent the formation of hot cracks during solidification. The microstructural analysis of the cross-section of the coating showed that the buffer layer diffused into the Fe3Al coating, forming a combination of Fe3Al, Fe, and Fe3AlC0.5 phases. The tribological properties of the Fe3Al-coated disc were evaluated using pin-on-disc tests against two different copper-free friction materials extracted from commercial brake pads. The wear results show a coefficient of friction comparable to that of an uncoated disc (≈0.55), but with a reduction in particulate matter (PM) emissions, which decreased from 600 to 476 #/cm3. The last issue is an interesting aspect that is gaining increasing importance in view of the upcoming international standards.

Comparative analysis of PODE3 and PODE4 fuel additives for emission reduction and soot characteristics in compression ignition engines

Polyoxymethylene dimethyl ethers (PODEn) have been regarded as promising fuel additives in reducing engine emissions due to their extra oxygen content and absence of C–C bonds. This research compares the effectiveness of PODE3 and PODE4 as fuel additives (10 % oxygen content) in a compression ignition (CI) engine. The results show that PODE can retard the ignition delay and shorten the combustion duration. They can both reduce HC emissions, with PODE4 having the greatest reduction. Both additives comparably reduce NOx emissions while consuming similar oxygen amounts. PODE alters particle size distribution, favoring higher nucleation mode particles and reducing accumulation mode particles, especially for the case with Diesel/PODE3. Further, this study investigates the soot characteristics when with different fuel blends. Thermogravimetric analysis (TGA) reveals enhanced oxidative reactivity in soot when with Diesel/PODE3 and Diesel/PODE4 fuel blends. Raman spectroscopy shows reduced crystalline structure and increased crystalline width in soot when with PODE additives. Fourier transform infrared (FT-IR) spectroscopy indicates improved relative intensity of aliphatic C–H groups and intensified aromatic C–H groups with PODE addition. In summary, PODE3 and PODE4 are promising CI engine fuel additives, substantially reducing particulate matter (PM) emissions and enhancing soot reactivity. These findings hold significance for cleaner combustion technologies.

Air Quality Analysis of Indoor Working Environments from Different Industries and Regions of Punjab

Background: Air pollution is a major health hazard and one of most crucial environmental aspects which cause mass mortality of population. Workers in different factories often directly exposed to particulate matter which can initiate respiratory related problems which may steer to incidence of cancer. Materials and Methods: Various particulate matter (PM) fractions and gaseous emissions were monitored in indoor environments of different industries using DRX Aerosol Monitor. Parallel monitoring of PM2.5 was performed in outdoor air by using TSI DUSTTRAK. Besides, analyses of indoor environment of different industrial units for volatile organic carbon (VOC’s), temperature, relative humidity, gaseous emissions (CO, CH4, O3, and NO2) was done by using Aeroqual. Results: The levels of particulate matter (PM) of all fractions and other criteria pollutant gases were significantly higher in all manufacturing units compared with recommended permissible WHO limits. Furthermore, PM2.5 levels were significantly higher in outdoor environment as compared to indoor workplaces at all monitored sites. Conclusion: There is a dire need to consider these high levels of PM and other gaseous emissions and take some serious steps to control this ever-increasing problem.

Ammonia and Particulate Matter Emissions at a Korean Commercial Pig Farm and Influencing Factors.

Quantifying emission factors of ammonia and particulate matter (PM) in livestock production systems is crucial for assessing and mitigating the environmental impact of animal production and for ensuring industry sustainability. This study aimed to determine emission factors of ammonia, total suspended particles (TSPs), PM10, and PM2.5 for piglets and growing-finishing pigs at a commercial pig farm in Korea. It also sought to identify factors influencing these emission factors. The research found that the emission factors measured were generally lower than those currently used in Korea, but were consistent with findings from individual research studies in the literature. Seasonal variations were observed, with ammonia emissions peaking in spring and autumn, and PM emissions rising in summer. Correlation analyses indicated that the number of animals and their average age correlated positively with both ammonia and PM emission factors. Ventilation rate was also positively correlated with PM emissions. Future extended field measurements across diverse pig farms will offer deeper insights into the emission factors of pig farms in Korea, guiding the development of sustainable livestock management practices.

Size-resolved particulate matter filtration efficiency of macroporous asymmetric SiC ceramic filters

Controlling particulate matter (PM) emissions to the atmosphere in industrial processes is critical for a safe and healthy environment. Because of its high strength and thermal stability, silicon carbide (SiC) is among the best materials for producing hot gas filters to be coupled to sugarcane bagasse-fired boilers in Brazil and India. In this study, we evaluated the performance of asymmetric SiC-based filters of different features for removing fine PM with particle sizes ranging from 90 to 3000 nm. The collection efficiency of the asymmetric filter made of SiC/mullite support with no pore former, porosity of 31–33 %, and permeability of (0.17–0.30) × 10−11 m2 with a coating thickness of 109–138 μm, effective pore size of 19–26 μm, and effective collector diameter of 64–86 μm was higher than 99 % for PM with size greater than 0.60 μm. The SiC formulation with mullite and pore former also presented promising performance. The resulting pressure drop remained within the range reported for commercial hot gas filters. Over 99 % of the mass of soot and fly ash particles generated during sugarcane bagasse combustion exceeds the MPPS range found for filters, which was between 0.16 and 0.36 μm. Therefore, the SiC asymmetric filters presenting mullite in their formulation are anticipated to meet current international emission standards.

Evaluation of the Source Concentration of Particulate Matter and Gaseous Emissions from Cement Milling and Grinding Facilities in Athi River, Machakos County, Kenya

Evaluation of the Source Concentration of Particulate Matter and Gaseous Emissions from Cement Milling and Grinding Facilities in Athi River, Machakos County, Kenya

Feasibility Analysis of Municipal Solid Waste Incineration for Harmless Treatment of Potentially Virulent Waste

The outbreak of major health emergencies, such as the COVID-19 pandemic, has posed numerous challenges to waste management. Environmentally sound treatment of such epidemic-related municipal solid waste (MSW) plays a vital role in interrupting virus transmission. In this study, the furnace type, incineration process and control parameters of an MSW incinerator were comparatively analyzed with those of a medical waste incinerator and hazardous waste incinerator according to China’s MSW incineration pollution control standards. In addition, changes in flue gas emissions data before, during and after the outbreak of the pandemic were empirically analyzed. The study revealed the following: (1) the feasibility of MSW incinerators to meet the harmless disposal of potentially viral municipal solid waste (PVMSW); (2) the priority order of incinerator types for MSW incinerators in the disposal of potentially virulent waste was grate furnace incinerator &gt; fluidized bed incinerator &gt; cement kiln; and (3) when MSW incinerators treated PVMSW, the emissions of dioxin compounds in the flue gas fluctuated between 0.00052 and 0.031 ng TEQ/m3, HCl emissions fluctuated between 1.6 and 23.742 mg/m3, CO emissions fluctuated between 0.18 and 59.15 mg/m3, heavy metal emissions fluctuated between 0.000008 and 0.855 mg/m3, and particulate matter emissions fluctuated between 0.64 and 12.13 mg/m3. All emissions met the flue gas emission standards. This study verified the feasibility of using MSW incinerators to treat PVMSW during a sudden major pandemic and provided a theoretical basis for the environmentally sound collaborative treatment of PVMSW and a reference for the emergency management and sustainable development of MSW.

Evaluation of air quality changes in a Chinese megacity over a 15-year period (2006–2021) using PM2.5 receptor modelling

Air quality impairment has a massive impact on human health, with atmospheric particulate matter (PM) playing a major role. The People's Republic of China experienced a trend of increasing PM2.5 concentrations from 2000 to 2013. However, after the application of the Air Pollution Prevention and Control Action Plan and other related control measures, sharp decreases in air pollutant concentrations were particularly evident in the city of Wuhan (central China). This study analysed major changes in PM2.5 concentrations, composition and source apportionment (using receptor modelling) based on Wuhan's PM2.5 chemical speciation datasets from 2006 to 2007, 2019–2021 and contemporaneous gaseous pollutant values. Average SO2 concentrations decreased by 88%, from the first to the second period, mostly due to measures that reduced coal combustion. However, NO2 only declined by 25%, with policy measures likely being undermined by an increased number of vehicles. PM2.5 concentrations decreased by 65%, with the PM constituents each being affected differently. Coal combustion-related element concentrations, OC, SO42−, NH4+, EC, Cl−, Al, Ca, Cu, Fe, Co and NO3− decreased by 22–90%. Secondary inorganic aerosol (SIA) was initially dominated by (NH4)2SO4 (73%) in 2006, but later dominated by NH4NO3 (52%) in 2021. Receptor modelling identified major sources contributing to PM2.5: Mineral, road and desert dust (MRDD), Secondary sulphate (SECS), Secondary nitrate (SECN), Tungsten industry (W), Toxic Elements of Coal (TEC), Iron and Steel (IRONS), Coal Combustion (CC), Residential Heating (RH), Refinery (REF) and Traffic (TRF). In relative proportions, TEC (−83%), SECS (−64%) and SECN (−48%) reduced their contributions to PM2.5 whilst MRDD increased (+62.5%). Thus, the results indicate not only a drastic abatement of PM pollution in Wuhan but also a change in the sources of pollution, which requires further actions to reduce PM2.5 concentrations to health protective values. Secondary PM and fugitive emissions are key components to abate.