Pollution Control Devices Research Articles

Identification of mercury species in coal combustion by-products from power plants using thermal desorption-atomic fluorescence spectrometry on-line coupling system

Along with the environmental protection policies becoming strict in China, the air pollution control devices (especially selective catalytic reduction (SCR)) are widely equipped in coal-fired power plants. The installation and run of these devices will inevitably affect mercury (Hg) species distribution in coal fired by-products such like fly ash (FA) and gypsum. In this work, a new on-line coupling system based on atomic fluorescence spectrometry (AFS) with a home-made chromatographic workstation was successfully developed to identify Hg species through thermal programmed desorption (TPD). The influences of matrix, furnace temperature, and carrier gas flow on analytical performance were investigated and the parameters were optimized. The FA and gypsum samples from coal-fired power plants equipped with SCR were collected and the mercury species were analyzed by the developed coupling system. HgCl2 and HgO were the main species in FA, while Hg2Cl2 and HgO were the main species in gypsum. All of Hg species in the studied FA and gypsum samples were released below 400 °C. A sequential extraction procedure was applied to further verify the operational Hg species including mobile and non-mobile fractions in FA and gypsum samples. This study demonstrated that AFS coupled with TPD procedure was an effective method to analyze Hg species in coal combustion by-products from power plants.

Design and construction of a gas filter system for hospital incinerators

An incinerator is designed to burn combustible waste materials such as municipal solid waste and infectious waste into inert ash. The design reduces waste volumes and subsequently destroys pathogens. A gas filtering unit is designed, constructed, and fitted on an existing incinerator for cleaning the smoke from medical waste treatment. Its main components are a framework whose material is made of galvanized diamond, three wire meshes, made of steel, to serve as filter bed supports, an inlet and 2 sampling holes of diameter 1.5cm beneath the wire meshes, and an outlet and 2 sampling holes of 1.5 cm above the wire meshes. As part of the gas filter design considerations, the amounts of dry volumetric gas discharged during combustion, and of particulate matter produced per cycle of combustion in the chosen incinerator were estimated to be 12,051.86 m3 /cycle, and 2.17 kg PM/cycle of incineration respectively. The novelty in this design consisted in adapting the impingement plate type of wet scrubbing unit for dry adsorption of organic pollutants in smoke using locally-activated charcoal powder. The incorporation of powdered activated charcoal in the filter unit as adsorbent material significantly reduces the emission of harmful pollutants into the atmosphere. As a result, pollution of the environment is minimized. The smoke was sampled before and after filtration, and the samples were later tested in the laboratory for 14 polychlorinated biphenyls, namely PCB 18, PCB 28, PCB 31, PCB 44, PCB 52, PCB 101, PCB 118, PCB 138, PCB 149, PCB 153, PCB 170, PCB 180, PCB 194 and PCB 209. The three charcoal filter beds used in the evaluation study achieved target pollutant reductions in smoke ranging from 2.03 % - 71.85%. An Air Pollution Control Device with such pollutant reductions should justify the continued use of incinerators if they are properly mounted and secured on the incinerators and can curb the problem of air pollution from point sources.

Distribution of the existence forms of condensable particulate matter during condensation: The surface collection and the space suspension forms

Condensable particulate matter (CPM), as an air pollutant that has received wide attention in recent years, has a high emission concentration compared to filterable particulate matter (FPM), yet there is not a well-developed removal method. Air pollution control devices (APCDs) with a condensation process have a certain effect on CPM removal, which inspired us to study the condensation behavior of CPM. During the condensation process, the condensed CPM may exist in two final forms: one was collected by the cold surface that caused the condensation; the other was converted to fine particles and suspended in the space of the flue. In a sense, the surface collection form can reflect the removal of CPM, while the CPM in the space suspension form should be further separated with the aim of removal. In this work, we adopted a CPM sampling system based on EPA Method 202 to reveal the distribution of the condensation behavior of CPM. In this sampling system, the CPM collected by all the cooling surfaces, including the cooling coil and impingers, can be counted as the surface collection form, while those collected by the terminal CPM filter can be regarded as the space suspension form. It was found that about 75 % of CPM was collected by the cooling surfaces, which suggested that CPM preferred to be in the surface collection form than the space suspension form. This preference characteristic also could be observed in the inorganic (CPMi) and organic components of the CPM (CPMo). Among the CPMi, almost all NH4+ and SO42− condensed in the form of surface collection. The preference characteristics in CPM's (and its components') condensation behavior are similar under every temperature reduction condition. In this work, the interference of CPM measurement error was resolved by the statistical method of ANOVA.

Effectiveness of Charcoal Adsorbent in Flue Gas Filters for PCB Reduction in Smoke from Hospital Incinerators

The release of gas-phase polychlorinated biphenyls (PCBs) as one of the persistent organic pollutants (POPs) is an unfortunate result of combustion, especially from medical waste incinerators. This tends to make incinerators unpopular. The idea of a cheaply available air pollution control device fitted to incinerator chimneys can justify the continued use of incinerators. A gas filter unit, consisting of 3 filter beds with activated charcoal as an adsorbent, was designed, constructed, and fitted onto an existing incinerator at a university hospital in Ghana. Flue gas from the incinerator was sampled before and after the filter beds, using cylindrically-shaped mini-polyurethane foam (mini-PUF) samplers, and the analytes in the samples were then Soxhlet-extracted, purified, and analyzed for certain PCBs using the gas chromatography-mass spectrometer (GC-MS) technique. Twelve of the 14 indicators PCBs analyzed in the smoke samples were present, and 11 of them saw mean reductions ranging from 3.67% to 54.9% by the charcoal filter beds. These were PCB 18, PCB 28, PCB 31, PCB 44, PCB 101, PCB 118, PCB 138, PCB149, PCB 153, PCB 170, and PCB180. The gaseous concentrations of PCBs before filtration ranged from 0.0000788 ng/m3 for PCB 180 to 0.00129 ng/m3 for PCB 153. After the filtration by the charcoal adsorbent, they ranged from 0.00003734 ng/m3 for PCB 170 to 0.00112016 ng/m3 for PCB 153. The highest mean reduction of 54.9% came from the homologue, PCB 180, whilst the homologue with a dioxin-like character (PCB 118) saw a 22.44% reduction. This suggests that dioxins and other dioxin-like compounds are most likely adsorbed by the charcoal adsorbent. This gas filter unit should further be investigated for its effectiveness at removing other dioxin-like PCBs, dioxins, and furanes and for testing the effectiveness of thermophilic bacterial strains that can further metabolize these POPs into less harmful products.

Systematic evaluation of decentralized thermal treatment of rural solid waste: Status, challenges, and perspectives

Rural solid waste (RSW) management in emerging economies is crucial in both improving the environment of rural areas and balancing the urban-rural disparity. The lack of capacity for RSW treatment and high cost of waste collection caused by long travelling distances contributed to the implementation and development of decentralized thermal treatment facilities (DTTFs) as a supplement to centralized facilities. Using China as a typical emerging economy for case study, this paper provides systematic evaluations of the rationality, performances, and challenges of decentralized thermal treatment in the context of RSW management development. The analysis results show that the operation performances of DTTFs, including the stability of reactors and the grade of syngas, are less satisfying in spite of the positive intention of their applications. Meanwhile, the emissions of CO, NOx, SO2 and PCDD/Fs varied depending on whether the syngas was combusted and the complexity of air pollution control devices (APCDs). The emissions of some DTTFs were unable to meet the national standard. Therefore, technological and managerial measures should be taken to improve the status of DTTFs. Waste sorting, operation optimization and proper APCDs are suggested, and the promotion of financial support, supervisory monitoring and training courses are important for the sustainability of RSW treatment.

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.

Investigation on Pollution Control Device (PCD) in iron foundry industry to reduce environmental chemicals.

Right from the olden days, many products have been made according to foundry practices in order to generate prosperity in the societies in which they operate while reaping these types of benefits through the operation of foundries. It is alarming that the emissions released by foundries affect human health. Therefore, foundries installed Pollution Control devices (PCDs), in accordance with this development; researchers examined the effectiveness of these PCDs in controlling emissions from foundries in different parts of the world. The emission control obtained by installing these PCDs is explained in this article based on the data gathered from the survey. The cartridge filter equipped with an induction furnace reduced the concentration of SPM to less than 20 mg/Nm3. This result of the investigation indicates that the cartridge filter built into the induction furnace achieves the best efficiency in controlling contaminants from iron foundries. Interestingly, the operation of the cartridge filter has yet to be documented. Therefore, the construction operation, the performance of the cartridge filter, and its efficiency in achieving contaminations control in foundries are described. This will provide useful information on the use of cartridge filters in an induction furnace to reduce Iron foundry emissions.

Particulate PCDD/F size distribution and potential deposition in respiratory system from a hazardous waste thermal treatment process

The particulate polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) of various sizes produced from the waste incinerators might have different toxicities, deposition characteristics, and potential health effects in the respiratory system, and their total toxicity equivalent (TEQ) concentration has been strictly regulated in recent years. There is a knowledge gap on the effects of air pollution control devices on particle size distributions (PSDs) of PCDD/Fs and their TEQ deposition. A hazardous waste thermal treatment plant equipped with an advanced scrubber, a cyclone demister, and activated carbon adsorption coupled with a baghouse filtration was investigated in this study. An 8-stage impactor was used to collect the particle distribution of PM10 and bounded PCDD/Fs from the gas stream at four sampling points located before and after each control unit. A “TEQDE” index is defined for the toxicity deposition of PM10-PCDD/F in the respiratory system. The advanced scrubbers significantly reduced the PM10-PCDD/F levels, especially for those with sizes ≥0.6 and ≤ 0.4 μm. Additionally, the cyclone also showed a better performance than the general dry gas treatment but had an efficiency drop with 1.5–4 μm particles. The PM10-PCDD/F loads in the final adsorption-filtration unit were eased and effectively removed the PM10-PCDD/Fs to sizes ≤0.5 or≥1.5 μm. The total TEQDE was 0.00052 ng WHO-TEQ Nm−3 and had a peak level of 0.000157 ng WHO-TEQ Nm−3 at 1.2 μm. PSDs were more sensitive to the PSDs of PM mass at high PM levels but strongly correlated with the PSDs of “PM10-PCDD/Fs/PM10” at low PM10 loads. Consequently, the advanced control system could effectively remove the PM10-PCDD/Fs and might extend the adsorption-filtration lifetime. However, the PM10-PCDD/Fs ≤ 0.4 μm had a higher TEQ deposition rate and should be further considered in emissions and ambient air quality evaluations.

Emission characteristics of filterable particulate matter and condensable particulate matter from coal-fired power plants

Particulate matter (PM) emission has been widely concerned all over the world. The formation of condensable particulate matter (CPM) was affected by atmospheric temperature. An optimal-designed sampling device and monitoring method for particulate matter in high-humidity flue gas were applied to the particulate matter emission concentration of 12 ultra-low emission coal-fired units. The emission levels and composition characteristics of particulate matter and main inorganic ions in the flue gas were analyzed and evaluated. The results showed that the filterable particulate matter (FPM) concentration range was 0.81–7.52 mg/m 3 , and the condensable particulate matter concentration range was 1.10–12.25 mg/m 3 . The emission characteristics of CPM/FPM was significantly affected by different air pollution control devices. Preferable emission reduction result of condensable particulate matter may be realized by units equipping wet limestone-gypsum flue gas desulfurization and wet electrostatic precipitator. The certain correlation was showed between CPM/FPM and ash content. The inorganic ion concentration range was 1104–8240 μg/m 3 in condensable particulate matter. Ca 2+ concentration accounted for more than 45% of the cation concentration, and SO 4 2− concentration accounted for up to 97.81% of the anion concentration in CPM.

A typical 300 MW ultralow emission coal-fired power plant: source, distribution, emission, and control of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are one of the dominant contributors to toxic organic pollutants emitted from coal combustion. In this study, the PAHs and condensable particulate matter (CPM) were sampled from a 300 MW ultralow emission coal-fired power plant. The effect of air pollution control devices (APCDs) on PAHs migration regularity and the influence of coal species changes on the emission of PAHs were studied. Note that the APCDs have definite selectivity for the removal of PAHs with different phases and ring numbers. The low-low temperature electrostatic precipitator (LLT-ESP) presented the best removal effect on PAHs (PAHs in flue gas, 29.92%; PAHs in CPM, 94.76%). The concentrations of PAHs were reduced at the outlet of the furnace (PAHs in flue gas, decreased from 3.318 to 2.850 μg/Nm3) and at the stack (PAHs in flue gas, decreased from 4.737 to 3.008 μg/Nm3; PAHs in CPM, decreased from 0.554 to 0.429 μg/Nm3) by replacing bituminous coal with blended coal (lower volatiles) as fuel. The adsorbent injection coupled with LLT-ESP had a preferable removal effect on the PAHs (decreased from 4.949 to 1.451 μg/Nm3), which was nearly 40% higher than the efficiency without the spray adsorbent.

Efficiency of Emission Reduction Technologies for Residential Biomass Combustion Appliances: Electrostatic Precipitator and Catalyst

Residential biomass combustion has been pointed out as one of the largest sources of atmospheric pollutants. Rising awareness of the environmental effects of residential biomass combustion emissions boosted the development of different emission reduction devices that are currently available on the market for small-scale appliances. However, detailed studies on the efficiency of these devices in different combustion systems available in Southern European countries are lacking. In this study, two pollution control devices (catalytic converter and electrostatic precipitator) were tested in two different combustion systems (batch mode operated woodstove and automatically fed pellet stove) in order to assess the emission reduction potential of the devices. Pine firewood was used to fuel the woodstove. One commercial brand of pellets and an agricultural fuel (olive pit) were taken for the experiments in the pellet stove. While the efficiency of the electrostatic precipitator in reducing PM10 was only recorded for woodstove emissions (29%), the effect of the catalyst in decreasing gaseous emissions was only visible when applied to the pellet stove flue gas. For wood pellet combustion, reductions of CO and TOC emissions were in the range of 60–62% and 74–77%, respectively. For olive pit combustion, a lower decrease of 59–60% and 64% in CO and TOC emissions, respectively, was recorded.

Utilization of municipal solid waste into electricity energy: A performance of PLTSa Bantargebang pilot project

Municipal solid waste (MSW) has become a serious problem for cities in Indonesia. The increasing population and economic activity as well as the increasing difficulty in obtaining land for landfills are the real problems faced. Waste generation from urban areas currently reaches 29.4 million tons annually and that has been managed reaches 62.29%. The Indonesian government has targeted 100% waste management by 2025 by processing 70% and reducing it by 30%. To accelerate the achievement of this target, Presidential Regulation No. 35/2018 concerning installation construction acceleration of waste processing into electricity energy based on environmentally friendly technology has been issued. MSW in Indonesia contains 62.4% of biomass in the form of food waste, wood, vegetables and fruits which have the potential to be a source of energy. This paper describes the performance of PLTSa Bantargebang based on operating data in 2020. PLTSa Bantargebang was designed to be able to burn 100 tonnes of waste/day with an average calorific value of 1,500 kcal/kg and an electricity output of 700 kW. This plant was also equipped with a pre-treatment plant to reduce water content and air pollution control devices that can emit exhaust that met national emission standards. When this study was conducted, the WtE plant electricity production was around 350 kW which was only used for the internal operational needs of the WtE plant. In this condition, the WtE plant burns waste on average 65 tons waste per day. During 2020, the plant had burned 9,878 tonnes of waste by generating electricity of 784 MWh or an electricity conversion rate of 110.66 kWh/ton waste. Both exhaust gas emission and liquid waste have met national quality standards, so that it is an environmentally friendly WtE plant. The plant also produced fly ash and bottom ash around 19.41% of the weight of the waste burned.

Quantitative assessment and mitigation measures of air pollution from crematoria in NCT of Delhi.

The modernization of crematoria and replacement of existing fuel requirements for better air quality is a key challenge in view of the associated religious beliefs in India where conventional open pyre funeral practices are followed. Unlike developed nations, the lack of appropriate site selection criteria, combustion efficient crematorium oven designs, and pollution control devices at these facilities necessitates formulation of appropriate policy measures to reduce emissions. The existing practices do not address such localized sources that affects the micro air pollution patterns owing to their marginal contribution in the total air pollution load of the city. The present study is thus an attempt to estimate emissions from 51 cremation grounds identified in NCT of Delhi. The study considers both particulate and gaseous pollutants which are released due to burning of fuels like wood, CNG, and cow dung. It is estimated that cremation activities contributed 393 tons/year of PM2.5, 142 tons/year of NOx, 29 tons/year of SO2, and 2686 tons/year of CO in year 2019. The maximum load was emitted from Central district as only Nigambodh Ghat crematoria receives on an average 60 bodies per day. Furthermore, air quality impact zone around crematoria has been demarcated using dispersion modelling considering crematorium with minimum and maximum number of bodies burnt in a day. The study also suggests control measures for reduction of pollution from cremation activities and delineates a buffer zone that could aid policymakers in establishing a site selection criterion to prevent the immediate population from likely exposure.

Electricity Generated by Waste Material

This paper introduce the future sustainability, there is great concern for the steady supply of affordable, renewable and clean energy sources with minimum societal and environment damage. To meet growing energy demands, solid waste is a great hope among the available renewable energy source. Inflammation dominates the waste-to-energy (WTE) market all over the world, and specifically in developed countries. After thermal processes, without oxygen digestion is the arising technology in clean energy production. Incineration in one of the thermal processes with low environmental impact and reduces the waste volume to be dumped in landfills. For the evaluation for the environmental impact of WTE technology, life-cycle asessement help to find suitable option for a particular region. Reduction of greenhouse gas emission and generation of alternatives to fossil fuel are major goal of Waste to Energy. Moreover the development of compact, cost-saving, yet highly efficient technology required, with the best solution for the disposal/utilization of filter ashes and residues from air pollution control devices.

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.

Distribution and emission characteristics of filterable and condensable particulate matter in the flue gas emitted from an ultra-low emission coal-fired power plant

Total particulate matter emitted from coal-fired power plants can be classified into filterable particulate matter (FPM) and condensable particulate matter (CPM). In this study, the FPM and CPM in the flue gas were sampled from a 300 MW ultra-low emission coal-fired power plant by the simultaneous sampling system, which was conducted according to ISO 23210-2009 and U.S. EPA method 202. The results show that the emission concentration of CPM rose from 5.15 mg/Nm3 to 7.19 mg/Nm3 at the stack when coal mixed with sludge. Almost all of the air pollutant control devices have a positive effect on the removal of CPM and FPM in the flue gas, except the influence of the selective catalytic reduction (SCR) denitration device on CPM. And the SCR denitration equipment increased the concentration of inorganic components of CPM in flue gas. The low-low temperature electrostatic precipitator had the most obvious removal effect on CPM and FPM, and the removal efficiency for FPM and CPM was more than 90% and 75% respectively. The organic fraction in CPM was mainly composed of hydrocarbons, esters, organosilicon, and other organics. In particular, the proportion of hydrocarbons and organosilicon was relatively high. In the case of co-combustion of sludge and coal, the concentration of CPM and FPM in flue gas increased as a whole, but the distribution trend of CPM and FPM was consistent with that of the non-combustion sludge and the distribution of organic components in CPM was almost the same.

Study on the condensable particulate matter removal characteristics of air pollution control devices in a Chinese ultra-low emission coal-fired generating unit

Condensable particulate matter (CPM) belongs to PM25. In addition, it is one of PM2.5 main contributors. But CPM emissions are often overlooked in coal-fired power plants. As a result, this paper studies the removal characteristics of (CPM) from air pollution control devices (APCDs) in a Chinese ultra-low emission coal-fired generating unit. The quality and content of flue gas particles, including CPM and filterable particulate matter (FPM), were measured at four points: the selective catalytic reduction (SCR) input, air preheater (APH) inlet, electric precipitator (ESP) outlet, and wet flue gas desulphurization (WFGD) outlet. The removal characteristics of each APCD were studied. Within the scope of this study, it is found that: ® CPM emission concentration accounts for 94.9% of total particle emission concentration, and is higher than the ultra-low particulate matter outflow guidelines for coal-fired power plants in China; ©WFGD has the highest CPM inorganic component removal radio of 97.02%, and ESP has the highest CPM organic component removal radio of 58.46%, among APCDs; ©SO4 2−, NH4 +, F−, and Cl− are the most abundant water-soluble ions in CPM.

Differentiated emission control strategy based on comprehensive evaluation of multi-media pollution: Case of mercury emission control

In order to comprehensively evaluate the environmental impact of multi-media mercury pollution under differentiated emission control strategies in China, a literature review and case studies were carried out. Increased human exposure to methylmercury was assessed through the dietary intake of residents in areas surrounding a typical coal-fired power plant and a zinc (Zn) smelter, located either on acid soil with paddy growth in southern China, or on alkaline soil with wheat growth in northern China. Combined with knowledge on speciated mercury in flue gas and the fate of mercury in the wastewater or solid waste of the typical emitters applying different air pollution control devices, a simplified model was developed by estimating the incremental daily intake of methylmercury from both local and global pollution. Results indicated that air pollution control for coal-fired power plants and Zn smelters can greatly reduce health risks from mercury pollution, mainly through a reduction in global methylmercury exposure, but could unfortunately induce local methylmercury exposure by transferring more mercury from flue gas to wastewater or solid waste, then contaminating surrounding soil, and thus increasing dietary intake via crops. Therefore, tightening air emission control is conducive to reducing the comprehensive health risk, while the environmental equity between local and global pollution control should be fully considered. Rice in the south tends to have higher bioconcentration factors than wheat in the north, implying the great importance of strengthening local pollution control in the south, especially for Zn smelters with higher contribution to local pollution.

Suggestion on further strengthening ultra-low emission standards for PM emission from coal-fired power plants in China

China has established the largest clean coal-fired power generation system in the world by accomplishing the technological transformation of coal-fired power plants (CFPPs) to achieve ultra-low emission. The potential for further particulate matter (PM) emission reduction to achieve near-zero emission for CFPPs has become a hotspot issue. In this study, PM emission from some ultra-low emission CFPPs adopting advanced air pollutant control technologies in China was reviewed. The results revealed that the average filterable particulate matter (FPM) concentration, measured as the total particulate matter (TPM) according to the current national monitoring standard, was (1.67±0.86) mg/m3, which could fully achieve the ultra-low emission standard for key regions (5 mg/m3), but that achieving the near-zero emission standard was difficult (1 mg/m3). However, the condensable particulate matter (CPM), with an average concentration of (1.06±1.28) mg/m3, was generally ignored during monitoring, which led to about 38.7% underestimation of the TPM. Even considering both FPM and CPM, the TPM emission from current CFPPs would contribute to less than 5% of atmospheric PM2.5 concentrations in the key cities and regions in China. Therefore, further reduction in FPM emission proposed by the near-zero emission plan of CFPPs may have less environmental benefit than emission control of other anthropogenic sources. However, it is suggested that the management of CPM emission should be strengthened, and a national standard for CPM emission monitoring based on the indirect dilution method should be established for CFPPs. Those measurements are helpful for optimal operation of air pollutant control devices and continuously promoting further emission reduction.

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

The Hazardous air pollutants (HAPs) released from increasing municipal solid waste incineration (MSWI) plants have drawn great concerns in China. However, a full picture of their emission characteristics is still urgently needed, especially after the implementation of stricter emission limits on MSWI. In this study, a comprehensive historical emission inventory of HAPs emitted from MSWI plants in China during the period of 2006–2017 was dedicatedly established by integrating with detailed plant-level activity data and renewed localized emission factors. Overall, HAPs emissions initially increased with years, then peaked or slowed increase in the year 2014, but leveled off after 2016 due to the gradually and fully implementing of newly revised national emission standard (GB18485–2014) applied to mainland China and much stricter local standards for several provinces and cities. It was estimated that totally 50,716 tons (t) of NOx, 13,026 t of CO, 7988 t of SO2, 4399 t of PM, 1943 t of HCl, 9916 kg of Pb, 5901 kg of Mn, 4805 kg of Cu, 3574 kg of Cr, 3329 kg of Ni, 2154 kg of Hg, 1168 kg of Cd, 862 kg of As, 409 kg of Co, 216 kg of Sb, 13 kg of Tl, and 19 g toxic equivalent quantity of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans were emitted from 337 MSWI plants scattered in 30 provinces of mainland China in 2017, respectively. HAPs emissions were heavily concentrated in developed coastal provinces and cities. Scenario analysis highlighted the importance of continuous improvement and upgrade on advanced air pollution control devices and MSWI management to meet the future ultra-low emission limits and minimize the harmful impacts of HAPs on atmospheric environment and public health.