Emissions Of Organic Pollutants Research Articles

Unintended side effect of the coal-to-gas policy in North China Plain: Migration of the sources and health risks of ambient PAHs.

Ongoing coal-to-gas (CTG) largely cut down both coal consumption and associated PM2.5. However, a knowledge gap still existed in CTG impacts on the other energy and organic pollutant emissions. Coupling on-site investigation with statistical yearbooks, we provided a more realistic energy evolutions before (BCTG), during (DCTG), and after (ACTG) the CTG for Hebei Province. Together, we examined the impacts of CTG derived energy conversion on PM2.5-bound PAHs at urban (UA)/suburban rural (SRA)/remote rural (RRA) sites in winter 2022. As expected, the consumptions of coal and natural gas (NG) far decreased and increased from BCTG to ACTG, respectively. Accidentally, biomass usage rose by 60.7%, and rural CTG acted as a main driver. Specially, SRA's NG-shortage and coal-stove demolition should be the main inducements, and RRA's coal-sale ban was another trigger in the early stage of CTG. ∑18PAHs and ∑8TPAHs stand for the sum of 18 PAHs and 8 toxic PAHs, respectively. ∑18PAHs (ng/m3) presented as SRA (81.8)>RRA (46.4)>UA (19.4). Biomass burning (BB) and NG combustion (NGC) contributed most to∑18PAHs of 31.0% and 23.1% at SRA, resulting in the highest ∑18PAHs, ∑18PAHs/PM2.5, and ∑8TPAHs/PM2.5, and incremental lifetime cancer risk values. Also, NGC has become the second largest contributor at UA. Variations in both diagnostic ratios and source-depend isomers further proved the prominence of NGC related PAHs at UA vs. SRA. Notably, RRA was least affected by the CTG, coal combustion (CC, 40.4%) and BB (32.6%) still occupied the top positions. In short, CTG gave rise to an upsurge in biomass usage, and the incremental PAHs emissions from BB vs. NGC. This study underlined that the priorities should be given to rural NG guarantee and subsidy retention, and biomass prohibition for further air quality improvement.

Robust and efficient oil-water separation using candle soot deposited stainless steel mesh

In recent years, the rising concerns regarding oil pollution and the emissions of organic pollutants from industrial activities have posed significant environmental and public health challenges. The treatment of oily wastewater and organic pollutants has emerged as pressing issue, necessitating the development of efficient solutions. Oil-water separation stands out as a promising approach to address these challenges. However, the effictiveness and robustness of the separating membranes have been identified as key limitations hindering the advancement of oil–water separation technologiess. This paper introduces a novel superhydrophilic/underwater superoleophobic membrane tailored specifically for oil–water separation with enhanced water flux. This film is prepared by depositing candle soot on a stainless steel mesh and then polymerizing phytic acid (CSM-PA). The contact angle of CSM-PA membranes underwater for a wide range of oils is above 140°, reaching a maximum of 152.73°. The CSM-PA membrane demonstrates excellent separation performance for various oils, achieving separation efficiencies flux surpassing 99.990 %, achieving separation efficiencies flux surpassing 18950.360 L·m−2·h−1. Notably, the membrane exhibits contact angles under water exceeding 142° for all oils tested. After conducting immersion, sand impact, and water impact tests, the underwater contact angle for both light and heavy oils was found to exceed 139°. The surface roughness of the CSM-PA film on the initial stainless steel mesh improved significantly, increasing from 106 nm to 452 nm. Impressively, even after 70 cycles, the CSM-PA membrane maintains an oil (n-hexane) water separation efficiency exceeding 99.997 % and a remarkable flux rate of 21055.956 L·m−2·h−1, the maximum separation flux is even 29154.400 L·m−2·h−1. Furthermore, the CSM-PA membrane shows significant stability and resistance to mechanical abrasion, ensuring long-term and reliable operational performance. The findings of this study hold significant implications for the advancement of oil–water separation technologies, offering a promising avenue for addressing oil pollution and organic pollutant emissions in a sustainable and effective manner.

Effect of changes in the fuel type of thermal power plants on the spatial distribution and levels of PAH pollution in the Vorkuta agglomeration beyond the Arctic Circle

The paper is a study of the composition of 15 polycyclic aromatic hydrocarbons (PAHs) in the snow cover of Vorkuta (Komi Republic) in the impact zone of the fuel and energy complex in 2017 and 2023. We have identified high aerotechnogenic pollution of the Vorkuta city and adjacent territories with PAHs during heating with fuel oil and coal, with a mean concentration of 301.6 ng/L (meltwater plus particles) and spatial distribution of 85.2 μg/m2. There is a significant decrease in PAH levels when the fuel for thermal power plants has been changed to natural gas, with a mean concentration of 26.1 ng/L (meltwater plus particulates) and spatial distribution of 4.9 μg/m2. The deposition areas of different PAH fractions are identified in the impact zones of Thermal Power Plants 1 and 2, the Central Boiler House and the urbanised areas of the Vorkuta agglomeration. 2-4-ring PAHs dominate in the emissions, accounting for 92–100 % of the sum of PAHs from coal/oil combustion and 66–93 % from natural gas combustion. The indicator ratios of PAHs in the snow cover of Vorkuta in both 2017 and 2023 indicate their predominantly pyrogenic genesis. The environmental risk coefficients of PAHs in the snow cover and their change from 2017 to 2023 are calculated. TEQ changed from 2.1 ng/L (mean) in the 2017 season to 1.7 ng/L (mean) in the 2023 season. The risk quotients have been reduced from moderate risk to low risk. Reconstruction of thermal power plants when replaced by more environmentally friendly fuel (natural gas) reduces the amount of atmospheric emissions of organic pollutants.

A superhydrophilic and robust fabric, featuring self-assembled layers of chitosan and carbon nanotubes, facilitates high-throughput oil–water separation

Petroleum pollution and industrial emissions of organic pollutants have become significant issues affecting both ecological and human living environments. High-performance oil–water separation membranes, due to their advantages such as low cost, environmental friendliness, and ease of operation, hold vast application prospects. Therefore, the development of efficient oil–water separation membranes is crucial. We propose a clever approach involving the synergistic self-assembly of chitosan (CS) and hydroxylated multi-walled carbon nanotubes (MWCNTs) on cotton fabric to construct a rough structure. Combined with hydrophilic modification using polyvinyl alcohol (PVA), not only does this enhance wettability, but it also addresses challenges related to mechanical strength and dispersibility of cotton fabric. The resulting CMF-PVA fabric performs well under challenging conditions, exhibiting excellent separation efficiency and permeance. Particularly noteworthy is that CMF-PVA achieves separation efficiencies exceeding 99.33 % for various organic substances, with a water flux reaching 35,476.52 L m−2 h−1 and a surfactant-stabilized emulsion permeance of 1199.0 L m−2 h−1·bar−1. Furthermore, CMF-PVA demonstrates outstanding mechanical durability under harsh conditions and excellent acid-base resistance. This method harnesses the inherent properties of CS and MWCNT self-assembly while enhancing the material's applicability on cotton fabric through hydrophilic modification. CMF-PVA fabric is poised to enhance selectivity, efficiency, anti-pollution properties, and accessibility in oil–water separation technology.

Research on Pollutant Emission Characteristics of Typical Biomass-fired Boilers

The combustion of biomass fuel boilers not only produces inorganic pollutants such as carbon oxides, nitrogen oxides, sulfur compounds, but also organic pollutants such as VOCs and PAHs, which directly affect the global biogeochemical cycle and atmospheric changes. Compared with foreign countries, there is relatively less research and related standards on the emission of organic pollutants from biomass fuel boilers in China. Therefore, it is necessary to study the emission characteristics of organic pollutants from biomass boilers, which can provide reference for the establishment of organic pollutant emission standards for biomass fuel boilers in China.The emission characteristics of volatile organic compounds(VOCs) and polycyclic aromatic hydrocarbons(PAHs) organic pollutants in the flue gas of three typical biomass-fired boilers in Chongqing were studied, and the emission concentrations of particulate matter, sulfur dioxides(SO2), and nitrogen oxides(NOX) were measured.The results show that the sulfur dioxide emissions from the three types of biomass-fired boilersrs are lower than the local standards in Chongqing, while nitrogen oxides and particulate matter have a phenomenon of exceeding the emission limits of the local standards in Chongqing. The main components of VOCs emitted from biomass powder and biomass particle combustion are OVOCs and aromatic hydrocarbons, while the main components of VOCs emitted from wood biomass combustion are alkynes. The gas-solid distribution pattern of PAHs during the combustion of three types of biomass is basically consistent. Low ring PAHs are mainly enriched in the gas phase, while medium and high ring PAHs are mainly enriched in particulate matter.

The influence of air pollution control devices on gas organic pollutants emission from coal-fired power plants based on LCA

Air pollutants (e.g., NOx, SO2) emitted from coal-fired power plants in China have been effectively controlled by Air Pollution Control Devices (APCDs) since 1996. However, the gas organic pollutants (typically Volatile Organic Compounds (VOCs) and Polycyclic Aromatic Hydrocarbons (PAHs)) have been overlooked for a long time. In this study, based on the life cycle assessment method, the effect of APCDs (mainly Selective Catalytic Removal (SCR), Electrostatic Precipitator (ESP), Wet Flue Gas Desulfurization (WFGD), and Wet Electrostatic Precipitator (WESP)) on gas organic pollutants (without methane) from three typical coal-fired power plants in China has been evaluated in terms of direct emission removal and indirect emissions. Detecting the gas organic pollutants concentrations at the inlet and outlet of APCDs in these three cases, it is found that the total direct emission removal efficiency is up to more than 71.97%, with SCR’s contribution being the highest. However, the manufacture and equipping of APCDs will lead to indirect emission of gas organic pollutants. The result shows that the SCR system is also the main process that induces indirect emissions of gas organic pollutants, associated with the utilization of liquid ammonia and catalyst. Compared to the direct emission of gas organic pollutants, indirect gas organic pollutants emissions can not be ignored. The calculation of net emission removal and the degree of co-effects shows that APCDs can reduce gas organic pollutants, which results in reducing the photochemical ozone creation potential of 1.81E-06~5.93E-06kg(Ethene eq.)/MW·h and human toxicity potential of 2.51E-03~8.06E-03kg (DCB eq.)/MW·h.

Urchin-like fluorinated covalent organic frameworks decorated fabric for effective self-cleaning and versatile oil/water separation

Oil contamination and industrial organic pollutants emission have been a serious problem affecting the ecological and residential environment. Membrane-based separation shows great application prospect due to its low-cost, environmental-friendly and easy operation. Therefore, the development of efficient oil-water separation membranes is highly desirable. Herein, a fabric filter with superwettability was prepared by coating urchin-like fluorinated covalent organic frameworks (COFs) on fabric, which was well utilized in filtering immiscible oil-water mixture and surfactant-stabilized water-in-oil emulsion driven only by gravity for the first time. The as-prepared COF fabric filter (defined as fabric@u-FCOF) possessed many outstanding properties, including superhydrophobicity with the water contact angle of approximately 151.6°, satisfactory resistance for alkaline, acidic and saline environments, as well as superior mechanical durability under harsh conditions. Because of the super-micropore of fabric@u-FCOF and the nanopore in the COF coating, the obtained fabric@u-FCOF exhibited excellent performances in terms of separation efficiency and permeability, in which the oil flux was up to 16964 L·m−1·h−2 and separation efficiency for the mixed o-dichlorobenzene/water was higher than 99.4%. In addition, the fabric@u-FCOF also showed excellent self-cleaning performance due to the micro/nano hierarchical structure of its surface. These excellent properties make it an ideal candidate for applications of oil/water separation and water purification.

Designing carbon nanotube sponge/Au@MgO2 for surface-enhanced Raman scattering detection and fenton-like degradation of organic pollutants

With the acceleration of industry and agriculture process, the massive emission of organic pollutants is a major problem which seriously restricts the sustainable development of society. Rapid enrichment, efficient degradation and sensitive detection are three key steps to solve the problem of organic pollutants, while developing a simple method integrating the above three capabilities is still a challenge. Herein, a three-dimensional carbon nanotube sponge decorated with magnesium peroxide and gold nanoparticles (CNTs/Au@MgO2 sponge) was prepared for surface enhanced Raman scattering (SERS) detection and degradation of aromatic organics by advanced oxidation processes. The CNTs/Au@MgO2 sponge with porous structures adsorbed molecules rapidly through π-π and electrostatic interaction, thus more aromatic molecules were driven to the hot-spot areas for highly sensitive SERS detection. A detection of limit with 9.09 × 10−9 M was achieved for rhodamine B (RhB). The adsorbed molecules were degraded by an advanced oxidation process utilizing hydrogen peroxide produced by MgO2 nanoparticles under acidic condition with 99% efficiency. In addition, the CNTs/Au@MgO2 sponge exhibited high reproducibility with the relative standard deviation (RSD) at 1395 cm−1 of approximately 6.25%. The results showed the sponge can be used to effectively track the concentration of pollutants during the degradation process and maintain the SERS activity by re-modifying Au@MgO2 nanomaterials. Furthermore, the proposed CNTs/Au@MgO2 sponge demonstrated the simultaneous functions of enrichment, degradation, and detection for aromatic pollutants, thus significantly expanding the potential applications of nanomaterials in environmental analysis and treatment.

Preparation of Fe2(MoO4)3/graphene/Ti nanocomposite electrode for visible-light photoelectrocatalytic degradation of organic pollutants

The massive emission of organic pollutants, specially organic dyes into water poses a serious threat to the environment and human health. Photoelectrocatalysis (PEC) has been regarded as an efficient, promising and green technology for organic pollution degradation and mineralization. Herein, Fe2(MoO4)3/graphene/Ti nanocomposite was synthesized and applied as a superior photoanode in a visible-light PEC process for degradation and mineralization of an organic pollutant. First, the Fe2(MoO4)3 was synthesized by the microemulsion-mediated method. Then, Fe2(MoO4)3 and graphene particles were simultaneously immobilized on a titanium plate by the electrodeposition technique. The prepared electrode was characterized by XRD, DRS, FTIR and FESEM analyses. The ability of the nanocomposite was investigated in the Reactive Orange 29 (RO29) pollutant degradation by the PEC. The Taguchi method was used for the visible-light PEC experiments design. The efficiency of RO29 degradation was enhanced with increasing bias potential, number of Fe2(MoO4)3/graphene/Ti electrodes, visible-light power and Na2SO4 (electrolyte) concentration. The pH of the solution was the most influential variable in the visible-light PEC process. Furthermore, the performance of the visible-light PEC was compared with photolysis, sorption, visible-light photocatalysis and electrosorption processes. The obtained results confirm the synergistic effect of these processes on RO29 degradation by the visible-light PEC.

Studying the Effect of different Temperatures Synthesis of Fe3O4/MnO2 Microrobots on Water Remediation

AbstractIndustrial emissions of organic pollutants pose a serious threat to the water environment on which people depend. The effective combination of MnO2‐based microrobots with Fe3O4 nanoparticles offers a promising solution to this challenge. In this work, Fe3O4/MnO2 microrobots were synthesised using a low‐cost and efficient one‐step hydrothermal method. It was found that the kinematic speed of the microrobots increased significantly with increasing synthesis temperature. In addition, the higher the synthesis temperature of Fe3O4/MnO2 microrobots, the more effective they were in removing organic pollutants. The results showed that different structures of MnO2 were produced at different temperatures and the effect of the synthesised microrobots at 80 °C, 100 °C and 130 °C on the catalytic performance and degradation effect was investigated. The Fe3O4/MnO2 microrobots synthesised at 130° showed the most favourable effect on the catalytic performance and degradation. This finding provides a new strategy for future microrobots for water remediation.

Elettaria cardamomum seed extract synthesized silver nanoparticles for efficient catalytic reduction of toxic dyes

The emissions of lethal organic pollutants, e.g., toxic dyes, from various industries result in the contamination of water, and hence, it is highly desirable to eradicate these pollutants. Herein, the catalytic reduction of hazardous methylene blue (MB) and rhodamine B (RhB) dyes has been evaluated (using sodium borohydride (NaBH4) as a reductant) by silver nanoparticles prepared from an extract of Elettaria cardamomum seeds (EC-Ag NPs). The UV–visible spectroscopy confirmed the successful formation of EC-Ag NPs. The results from the transmission electron microscopic (TEM) study indicated the spherical shape with an average particle size of 5.4 nm, along with the crystalline nature of EC-Ag NPs revealed from the XRD study. What is more, the FTIR result verified the existence of phytoconstituents that act as both stabilizing and reducing agents. The as-synthesized ES-Ag NPs showed excellent activity in the catalytic reduction of both lethal dyes (MB and RhB) in the presence of NaBH4. The reduction results revealed that it takes 7 and 10 min, respectively, to completely eradicate the MB and RhB, with rate constants of 0.328 and 0.244 min−1, which are significantly better than those previously reported. In addition, the as-synthesized ES-Ag NPs exhibit outstanding stability up to several rounds during the reduction of both dyes, proving their practical applicability at industrial and domestic levels.

Insights into seasonal-variability of SVOCs, morpho-elemental and spectral characteristics of PM2.5 collected at a dense industrial site: Faridabad, Haryana, India

The development-oriented anthropogenic activities have led to intensive increase in emission of various organic pollutants, which contribute considerably to human health risk. In the present study, chemical, physical and spectral characterisation of fine particulate matter (PM2.5), collected at Faridabad city, in northern India, were examined. Seasonal variation of organic compounds [n-alkanes, polyaromatic hydrocarbons (PAHs) and phthalic acid esters (PAEs)], and potential health risk of Polyaromatic hydrocarbons (PAHs) exposure using toxic equivalency potential (TEQ) approach had been assessed. These showed seasonal average values ranging from 156.4 ± 57.0 ng/m3 to 217.6 ± 72.9 ng/m3, 98.0 ± 21.4 ng/m3 to 177.8 ± 72.8 ng/m3, and 30.9 ± 11.9 ng/m3 to 82.5 ± 29.2 ng/m3, respectively, with the highest value for winter. It is noteworthy that unlike, n-alkanes and PAEs, PAHs were least during spring. The high molecular weight PAHs (BaP, BkF, DahA and IcdP) were found to exhibit higher TEQ values (ranging from 0.7 to 9.7) despite of their lower concentrations. The PAH diagnostic ratio, carbon preference index and total index revealed the enhanced impact of biogenic sources of emissions in comparison to diesel emission sources during winter.

Criteria for the Assessment of Health Risk from a Waste Gasification Plant

Abstract In mountainous regions, the atmospheric dispersion of air pollutants is limited by complex terrain morphology. Trentino (a province located in the Italian Alps) is characterized by a high population density, highly developed agriculture and farming, and the presence of civil and industrial activities, whose emissions tend to be trapped inside the valleys. These conditions translate into exposure levels that are potentially higher than other geographical contexts (e.g., flat or coastal regions). The academic research carried out in Trentino since 2005 has produced a series of publications on topics related to the risk for health derived from waste management and other activities. These publications has focused on: 1) the evaluation of the emissions of organic pollutants from the waste sector; 2) the monitoring of persistent organic pollutants (POPs) in various environmental matrices; 3) a methodology to carry out a comprehensive health risk assessment considering all the relevant exposure routes in an area; 4) the role of the local diet in the exposure of a population to POPs; 5) methodologies to define new regulatory limit values for dioxin and hexavalent chromium; and 6) the role of dispersion modeling in assessing the exposure to air pollutants. The present paper will review these publications and provide a reference document to evaluate new project proposals that require a health risk assessment and facilitate the work of proponents, clarifying the requirements of a health risk assessment. The paper will refer to waste gasification, but the considerations expressed in this paper may apply to other activities.

Dioxin-like POPs emission trends as a decision support tool for developing sustainable MSW management scheme –an exploratory study

The paper reports on an innovative application of dioxin-like persistent organic pollutants (dl-POPs) emission trends as a measure of environmental performance for designing feasible municipal solid waste management (MSWM) schemes. MSWM systems are highly dependent on the income status and the population density and it is quintessential for developing countries to devise strategies suiting to its characteristics rather than simply adapting successful processes/technologies in developed nations. Hence a lower-middle-income, high-density populated state of India – Kerala, which represents the typical scenario of majority of towns in developing countries was selected as the verification study site. Annual inventorisation of dl-POPs for the current scenario of the state was developed as a spatial model at the lowest administrative block level using geographical information system for the easy and effective comparative assessment. Further, a dl-POPs emission based MSWM scheme which could reduce up to 65% of emissions from current scenario has been developed and compared it with contemporary life cycle assessment (LCA) and life cycle cost analysis (LCCA) schemes in terms of green-house gas emissions (GHG) and landfill area requirements as environmental performance validation. Daily exposure dose of dl-POPs were predicted from the per-capita annual emission associated with different MSWM schemes and hazard quotients were also calculated to provide an overview of the health risk posed by the emissions. The predicted health risk factors were observed to be 5 times higher than the threshold level in current scenario whereas 10 times reduction in dose levels could be achieved through the proposed scheme of MSWM.

Nano TiO2 and Molybdenum/Tungsten Iodide Octahedral Clusters: Synergism in UV/Visible-Light Driven Degradation of Organic Pollutants.

Emissions of various organic pollutants in the environment becomes a more and more acute problem in the modern world as they can lead to an ecological disaster in foreseeable future. The current situation forces scientists to develop numerous methods for the treatment of polluted water. Among these methods, advanced photocatalytic oxidation is a promising approach for removing organic pollutants from wastewater. In this work, one of the most common photocatalysts-titanium dioxide-was obtained by direct aqueous hydrolysis of titanium (IV) isopropoxide and impregnated with aqueous solutions of octahedral cluster complexes [{M6I8}(DMSO)6](NO3)4 (M = Mo, W) to overcome visible light absorption issues and increase overall photocatalytic activity. XRPD analysis showed that the titania is formed as anatase-brookite mixed-phase nanoparticles and cluster impregnation does not affect the morphology of the particles. Complex deposition resulted in the expansion of the absorption up to ~500 nm and in the appearance of an additional cluster-related band gap value of 1.8 eV. Both types of materials showed high activity in the photocatalytic decomposition of RhB under UV- and sunlight irradiation with effective rate constants 4-5 times higher than those of pure TiO2. The stability of the catalysts is preserved for up to 5 cycles of photodegradation. Scavengers' experiments revealed high impact of all of the active species in photocatalytic process indicating the formation of an S-scheme heterojunction photocatalyst.

Polymer–assisted preparation of porous wood–based metallic composites for efficient catalytic reduction of organic pollutants

The unreasonable emission of nitroaromatic organic pollutants (NOPs) has threatened the ecological environment. However, the existing catalytic materials for NOPs reduction can not meet the actual practical application due to various functional deficiencies. In this work, novel cellulose–based metallic composites with high catalytic activity for NOPs reduction were developed through polymer–assisted electroless deposition (ELD) technique coating metallic nanoparticles onto cellulose–based porous wood surfaces. The fabricated metallic composites display outstanding catalytic ability, catalytic universality and excellent durability for most NOPs, due to the uniform catalytic metal coating enabled by polymer–assisted ELD approach and sufficient catalytic sites provided by the porous wood host surfaces. The continuous flow catalytic systems using the fabricated bulk composites were further demonstrated showing the broad prospects of such designed metallic composites in actual practical applications. This work provides a new avenue to realize rational design and large–scale fabrication of novel high–performance catalysts for NOPs reduction applications.

Release characteristics of organic pollutants during co-firing coal liquefaction residue in a circulating fluidized bed boiler

Coal liquefaction residue (CLR) is usually categorized as hazardous waste, which is inevitably generated during the coal-liquefaction process. Studies show that CLR has a high calorific value and can be used to decrease coal consumption during the co-firing process. In this regard, field tests were carried out to study the emission and environmental risks of organic pollutants during co-firing CLR in a circulating fluidized bed (CFB) boiler. In the present study, the effects of co-firing CLR on the operating conditions of the boiler and the concentrations of 16 polycyclic aromatic hydrocarbons (PAHs), hexachlorobenzene (HCB), dioxins, dioxin-like polychlorinated biphenyls (dl-PCBs), volatile organic compounds (VOCs), and total organic carbons (TOCs) in the flue gas, fly ash, and bottom ash were investigated. It is found that burning the fuel consisting of 85 % coal and 15 % CLR by mass decreases the coal consumption by 2–3 t/h while the combustion parameters almost remain intact. The performed analyses reveal that co-firing the CLR does not increase the emission of PAHs compared to pure coal combustion. Meanwhile, it is found that fly ash has a high concentration of PAHs while the concentration is relatively low in the bottom ash. Doped with m-dichlorobenzene as an organic marker, the destruction removal efficiency (DRE) exceeds 99.99 %. The releases of organic pollutants during the co-firing process are lower than the specified limit in relevant environmental standards.

Regulation of organic hydrocarbon pollutants in coal volatiles combustion with CO2 addition

Considering the important effect of coal volatiles combustion on coal-fired organic pollutants formation, coal pyrolysis gas was selected as fuel in this work. Spatial profiles of light hydrocarbons and aromatic hydrocarbons in counterflow diffusion flames (CDFs) were detected by gas chromatography and gas chromatography-mass spectrometer, combined with chemical reaction kinetic analysis. As the main component of exhaust gas, CO2 could significantly affect hydrocarbons formation in flames. By adding CO2 to the oxidizer of CDF, the regulation of CO2 addition on organic products during coal pyrolysis gas combustion was studied. The results showed that the dilution/thermal and chemical effects of CO2 all decreased the mole fractions of H, thereby inhibiting the formation of acetylene (C2H2), propargyl (C3H3), propyne (PC3H4), 1,3-butadiene, vinylacetylene, diacetylene, benzene (C6H6), toluene and naphthalene in the flame. With CO2 addition, the path from C2H2 to PC3H4 was inhibited, and less C3H3 formed C6H6 through self-recombination, while more favored to form C6H6 through fulvene. Decrease in the concentration of above-mentioned soot precursors indicated that adding CO2 could effectively inhibit the emission of organic pollutants during coal combustion process.

Concentration, variation, and correlation with traffic vehicle volume of the pollutants - polycyclic aromatic hydrocarbons (PAHs) in street dust in Hanoi

The average concentration of 16 PAHs in street dust in Hanoi (n=27) was 1,226 ng/g, ranging from 532 to 2,276 ng/g. The total toxic equivalent amount of 16 PAHs, in comparison with BaP, TEQBaP was 121.58 ng/g on average and varried in a range of 35.36 and 322.22 ng/g. Amongst 16 analysed PAHs, the most abundant compounds were Pyr (16.4%)>BbF (14.0%)~Fluth (14.0%)>BghiP (12.3%)>Phe (7.9%). However, BaP occupied up to 52.6% of the toxic equivalent amount, followed by DahA (15.9%) and BkF (14.2%). In Hanoi street dust, the ratios of some special PAHs such as Fluth/Fluth+Pyr (0.46±0.04); BaA/Chr in a range of 0.27-0.49 (occupied 60% of the dust sample amount), and IcdP/BghiP (0.40±0.11), showed that the main emission source of PAHs in Hanoi road dust was from traffic vehicles using gasoline. The PAHs concentrations in street dust in Hanoi tended to be reduced up to approximately 10% in the observation for a few recent years despite the increasing traffic vehicle volume of the city. That means the better traffic vehicles and road management in Hanoi, the lesser emission of toxic organic pollutants, especially PAHs, to the ambient air.

Control of extreme brominated persistent organic pollutant emissions from start-ups of waste-to-energy incinerators

Unlike chlorinated persistent organic pollutants (Cl-POPs), few studies have investigated the emissions of brominated POPs (Br-POPs), including polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), polybrominated biphenyls (PBBs), and polybrominated diphenyl ethers (PBDEs), from start-up processes of municipal solid waste incinerators (MSWIs). Presently, there are no studies published on Br-POP control during this period. This study found that start-up processes could contribute to at least 27%, 55%, and 2% PBDD/F, PBB, and PBDE emissions of an entire year of MSWI operations. High PBDD/F and PBDE emission rates were observed at the beginning of the start-up, indicating that control measures should be conducted before or at the beginning of the start-ups. PBBs behaved like Cl-POPs with high emission rates observed at the POP-formation temperature window (250–450 °C). Unlike Cl-POPs, inhibiting adsorptive memory effects by cleaning the accumulated ash was the most effective control strategy for PBDD/F and PBDE emissions, accounting for 72.8% and 51.3% of total reductions, respectively. Contrarily, inhibiting Br-POP formation by cleaning the accumulated ash and shortening the residence time of the flue gas in 250–450 °C contributed to the highest PBB reduction (67.5%). Overall, the control strategies reduced PBDD/F and PBB emissions by >97% and PBDEs by 61%. This study shows that PBDD/Fs and PBDEs behave differently from their chlorinated equivalents and require different control strategies. In conclusion, the control strategies proposed can reduce Br-POP emissions during start-up successfully, and they require no modifications to existing control devices.