An online technology for effectively monitoring inorganic condensable particulate matter emitted from industrial plants

Emission characteristics of condensable particulate matter during the production of solid waste-based sulfoaluminate cement: Compositions, heavy metals, and preparation impacts

Recycling solid waste for preparing sulfoaluminate cementitious materials (SACM) represents a promising approach for low-carbon development. There are drastic physical-chemical reactions during SACM calcination. However, there is a lack of research on the flue gas pollutants emissions from this process. Condensable particulate matter (CPM) has been found to constitute the majority of the primary PM emitted from various fuel combustion. In this study, the emission characteristics of CPM during the calcination of SACM were determined using tests in both a real-operated kiln and laboratory experiments. The mass concentration of CPM reached 96.6 mg/Nm3 and occupied 87% of total PM emission from the SACM kiln. Additionally, the mass proportion of SO42- in the CPM reached 93.8%, thus indicating that large quantities of sulfuric acid mist or SO3 were emitted. CaSO4 was one key component for the formation of main mineral ye'elimite (3CaO·3Al2O3·CaSO4), and its decomposition probably led to the high SO42- emission. Furthermore, the use of CaSO4 as a calcium source led to SO42- emission factor much higher than conventional calcium sources. Higher calcination temperature and more residence time also increased SO42- emission. The most abundant heavy metal in kiln flue gas and CPM was Zn. However, the total condensation ratio of heavy metals detected was only 40.5%. CPM particles with diameters below 2.5 μm and 4-20 μm were both clearly observed, and components such as Na2SO4 and NaCl were conformed. This work contributes to the understanding of CPM emissions and the establishment of pollutant reduction strategies for waste collaborative disposal in cement industry.

The effect of multiple factors on changes in organic-inorganic fractions of condensable particulate matter during coal combustion

Condensable particulate matter (CPM) from coal combustion is the focus of current pollutant emission studies, and CPM can be divided into inorganic and organic fractions according to the component characteristics. At present, the effects of different factors in the combustion process on the organic and inorganic components of CPM have not been discussed systematically. Here, we conducted combustion experiments collected the generated CPM on a well-controlled drip tube furnace, and investigated the effects of different factors on the generation of organic and inorganic components of CPM by varying the furnace wall insulation temperature, the ratio of gas supply components and the water vapor content in the flue gas. The results showed that the increase in combustion temperature (1300-1500 °C) and oxygen concentration (15-25%) reduced the total CPM generation by 9.8% and 19.98%, respectively, and the intervention of water vapor increased the ability of the whole CPM sampling device to capture ultrafine condensable particles. The generation of CPM organic components decreased with the enhancement of combustion temperature and oxygen content on combustion characteristics, and alkanes shifted to low carbon content. The amount of CPM inorganic components increased with the increase of water vapor content in the flue gas, and this change was dominated by SO42-. The above results provide a feasible idea for the next step of the precise reduction of CPM components.

Field application of hydroxyapatite and humic acid for remediation of metal-contaminated alkaline soil

The quality of soil is essential for ensuring the safety and quality of agricultural products. However, soils contaminated with toxic metals pose a significant threat to agricultural production and human health. Therefore, remediation of contaminated soils is an urgent task, and humic acid (HA) with hydroxyapatite (HAP) materials was applied for this study in contaminated alkaline soils to remediate Cd, Pb, Cu, and Zn. Physiochemical properties, improved BCR sequential extraction, microbial community composition in soils with superoxide dismutase (SOD), peroxidase (POD), and chlorophyll content in plants were determined. Among the studied treatments, application of HAP-HA (2:1) (T7) had the most significant impact on reducing the active forms of toxic metals from soil such as Cd, Pb, Cu, and Zn decreased by 18.59%, 9.12%, 11.83%, and 3.33%, respectively, but HAP and HA had a minor impact on metal accumulation in Juncao. HAP (T2) had a beneficial impact on reducing the TCleaf/root of Cd, Cu, and Zn, whereas HAP-HA (T5) showed the best performance for reducing Cd and Cu in EFleaf/soil. HAP-HA (T5 and T7) showed higher biomass (57.3%) and chlorophyll (17.9%), whereas HAP (T4) showed better performance in POD (25.8%) than T0 in Juncao. The bacterial diversity in soil was increased after applying amendments of various treatments and enhancing metal remediation. The combined application of HAP and HA effectively reduced active toxic metals in alkaline soil. HAP-HA mixtures notably improved soil health, plant growth, and microbial diversity, advocating for their use in remediating contaminated soils.

Aerial monitoring of atmospheric particulate matter produced by open-pit mining using low-cost airborne sensors

Mining is an economic activity that entails the production and displacement of significant amounts of atmospheric particulate matter (PM) during operations involving intense earthcrushing or earthmoving. As high concentrations of PM may have adverse effects on human health, it is necessary to monitor and control the fugitive emissions of this pollutant. This paper presents an innovative methodology for the online monitoring of PM10 concentrations in air using a low-cost sensor (LCS, <300 USD) onboard an unmanned aerial vehicle. After comprehensive calibration, the LCS was horizontally flown over seven different areas of the large Riotinto copper mine (Huelva, Spain) at different heights to study the PM10 distribution at different longitudes and altitudes. The flights covered areas of zero activity, intense mining, drilling, ore loading, waste discharge, open stockpiling, and mineral processing. In the zero-activity area, the resuspension of PM10 was very low, with a weak wind speed (3.6 m/s). In the intense-mining area, unhealthy concentrations of PM10 (>51 μgPM10/m3) could be released, and the PM10 can reach surrounding populations through long-distance transport driven by several processes being performed simultaneously. Strong dilution was also observed at high altitudes (> 50 m). Mean concentrations were found to be 22-89 μgPM10/m3, with peaks ranging from 86 to 284 μgPM10/m3. This study demonstrates the potential applicability of airborne LCSs in the high-resolution online monitoring of PM in mining, thus supporting environmental managers during decision-making against fugitive emissions in a cost-effective manner.

Emission characteristics of condensable particulate matter (CPM) from FCC flue gas

Particulate matter (PM) as a major air pollutant, generally includes filterable particulate matter (FPM) and condensable particulate matter (CPM). CPM has gradually attracted widespread attention recently, due to its increasing proportion in total PM emissions. Fluid catalytic cracking (FCC) units, the main emission source in refineries, mostly use wet flue gas desulfurization (WFGD), which will produce a large amount of CPM. However, CPM emission and composition of FCC units are actually unclear. In this work, we aimed to understand the emission characteristics of CPM in FCC flue gas and provide some potential control strategies. Here, the stack tests of three typical FCC units were conducted to monitor FPM and CPM, and the field monitoring FPM results are higher than the concentration provided by Continuous Emission Monitoring System (CEMS). The emission of CPM is at a high-level concentration from 28.88 to 86.17 mg/Nm³, divided into inorganic fraction and organic fraction. The inorganic fraction is mainly composed in CPM, where water-soluble ions including SO₄^2-, Na⁺, NH₄⁺, NO₃^-, CN^-, Cl^-, and F^-, are the major contributors. Moreover, a variety of organic compounds are detected as qualitative analysis of organic fraction in CPM, which can be roughly classified into alkanes, esters, aromatics, and others. Finally, on the basis of the understanding of the characteristics of CPM, we have proposed two strategies for CPM control. This work is expected to advance CPM emission regulation and control in FCC units.

Developed compositional source profile and estimated emissions of condensable particulate matter from coal-fired power plants: A case study of Yantai, China

The emission and environmental impact of condensable particulate matter (CPM) from coal-fired power plants (CFPPs) are of increasing concern worldwide. Many studies on the characteristics of CPM emission have been conducted in China, but its source profile remains unclear, and its emission inventory remains high uncertainty. In this work, the latest measurements reported in the latest 33 studies for CPM inorganic and organic species emitted from CFPPs in China were summarized, and then a compositional source profile of CPM for CFPPs was developed for the first time in China, which involved 10 inorganic species and 71 organic species. In addition, the CPM emission inventory of CFPPs in Yantai of China was developed based on surveyed activity data, continuous emission monitoring system (CEMS), and the latest measurement data. The results show that: (1) Inorganic species accounted for 77.64 % of CPM emitted from CFPPs in Yantai, among which SO₄^2- had the highest content, accounting for 23.74 % of CPM, followed by Cl^-, accounting for 11.95 %; (2) Organic matter accounted for 22.36 % of CPM, among which alkanes accounted for the largest proportion of organic fraction (72.7 %); (3) Emission concentration method (EC) and CEMS-based emission ratio method (ER_FPM,CEMS) were recommended to estimate CPM emissions for CFPPs; (4) The estimated CPM emission inventories of Yantai CFPPs in 2020 by the EC method and the ER_FPM,CEMS method were 1231 tons and 929 tons, respectively, with uncertainties of -34 % ∼ 33 % and -27 % ∼ 57 %, respectively; (5) CPM emissions were mainly distributed in the northern coastal areas of Yantai. This developed CPM source profile and emission inventory can provide basic data for assessing the impacts of CPM on air quality and health. In addition, this study can provide an important methodology for developing CPM emission inventories and CPM emission source profiles for stationary combustion sources in other regions.

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 (CPM_i) and organic components of the CPM (CPM_o). Among the CPM_i, almost all NH₄⁺ and SO₄^2- 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.

Particulate Matter and Its Components Induce Alteration on the T-Cell Response: A Population Biomarker Study

Compared with the T-cell potential of particulate matter (PM) in animal studies, comprehensive evaluation on the impairments of T-cell response and exposure-response from PM and its components in human population is limited. There were 768 participants in this study. We measured environmental PM and its polycyclic aromatic hydrocarbons (PAHs) and metals and urinary metabolite levels of PAHs and metals among population. T lymphocyte and its subpopulation (CD4⁺ T cells and CD8⁺ T cells) and the expressions of T-bet, GATA3, RORγt, and FoxP3 were measured. We explored the exposure-response of PM compositions by principal component analysis and mode of action by mediation analysis. There was a significant decreasing trend for T lymphocytes and the levels of T-bet and GATA3 with increased PM levels. Generally, there was a negative correlation between PM, urinary 1-hydroxypyrene, urinary metals, and the levels of T-bet and GATA3 expression. Additionally, CD4⁺ T lymphocytes were found to mediate the associations of PM_2.5 with T-bet expression. PM and its bound PAHs and metals could induce immune impairments by altering the T lymphocytes and genes of T-bet and GATA3.