Atmosphere-dependent combustion of Ganoderma lucidum biomass toward its enhanced transformability into green energy.

Globally, the circular efficiency of biomass resources has become a priority due to the depletion and negative environmental impacts of fossil fuels. This study aimed to quantify the atmosphere-dependent combustion of Ganoderma lucidum (GL) biomass and its thermodynamic and kinetic parameters toward enhancing its circularity and transformability characteristics. The GL combustion occurred in the three stages of moisture removal, volatile release, and coke combustion. Combustion performance characteristics were more favorable in the N2/O2 atmosphere than in the CO2/O2 atmosphere under the same heating rates. The rising heating rate facilitated the release of volatiles. According to the model-free methods of Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose, the activation energies essential for the primary reaction were 283.09 kJ/mol and 288.28 kJ/mol in the N2/O2 atmosphere and 233.09 kJ/mol and 235.64 kJ/mol in the CO2/O2 atmosphere. The gaseous products of the GL combustion included CH4, H2O, C = O, CO, CO2, NH3, C = C, and C-O(H). Ash prepared in both atmospheres exhibited a tendency for slag formation, with oxy-fuel combustion lowering its risk. This study thus provides a theoretical and practical basis for transforming GL residues into a sustainable energy source.

Identification and health risk evaluation of soil contaminated by polycyclic aromatic hydrocarbons at shale gas extraction sites based on positive matrix factorization.

The impact of shale gas extraction on surrounding environmental media remains unclear. In this study, the current state of contamination by polycyclic aromatic hydrocarbons (PAHs), which are high-frequency contaminants of shale gas, was investigated in the soil surrounding emerging shale gas development sites. The source analysis of PAHs was conducted in the soils of shale gas extraction sites using positive matrix factorization (PMF). The health risk assessment (HRA) was calculated for ingestion, dermal contact, and inhalation exposures, and the priority sources of PAHs in the soil were jointly identified by PMF and HRA to refine the contribution level of different individual PAHs to the carcinogenic risk. The results showed that both Sichuan and Chongqing mining site soils were contaminated to different degrees. Shale gas extraction has an impact on the surrounding soil, and the highest contributing source of PAHs in the mining site soil of Sichuan was anthropogenic activity, accounting for 31.6%, whereas that in the mining site soil of Chongqing was biomass combustion and mixed automobile combustion, accounting for 35.9%. At the two mining sites in Sichuan and Chongqing, none of the three exposure pathways (ingestion, dermal contact, and inhalation) posed a carcinogenic risk to children, whereas the dermal exposure pathway posed a carcinogenic risk to adults. Health risk assessments based on specific source assignments indicate that when managing soil pollution, the control of fossil fuel combustion and vehicular emissions should be prioritized.

First Insight into Fetal Exposure to Legacy and Emerging Plasticizers Revealed by Infant Hair and Meconium: Occurrence, Biotransformation, and Accumulation.

Epidemiological studies have demonstrated the embryonic and developmental toxicity of plasticizers. Thus, understanding the in utero biotransformation and accumulation of plasticizers is essential to assessing their fate and potential toxicity in early life. In the present study, 311 infant hair samples and 271 paired meconium samples were collected at birth in Guangzhou, China, to characterize fetal exposure to legacy and emerging plasticizers and their metabolites. Results showed that most of the target plasticizers were detected in infant hair, with medians of 9.30, 27.6, and 0.145 ng/g for phthalate esters (PAEs), organic phosphate ester (OPEs), and alternative plasticizers (APs), and 1.44, 0.313, and 0.066 ng/g for the metabolites of PAEs, OPEs, and APs, respectively. Positive correlations between plasticizers and their corresponding primary metabolites, as well as correlations among the oxidative metabolites of bis(2-ethylhexyl) phthalate (DEHP) and 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), were observed, indicating that infant hair retained the major phase-I metabolism of the target plasticizers. While no positive correlations were found in parent compounds or their primary metabolites between paired infant hair and meconium, significant positive correlations were observed among secondary oxidative metabolites of DEHP and DINCH in hair and meconium, suggesting that the primary metabolites in meconium come from hydrolysis of plasticizers in the fetus but most of the oxidative metabolites come from maternal-fetal transmission. The parent compound/metabolite ratios in infant hair showed a decreasing trend across pregnancy, suggesting in utero accumulation and deposition of plasticizers. To the best of our knowledge, this study is the first to report in utero exposure to both parent compounds and metabolites of plasticizers by using paired infant hair and meconium as noninvasive biomonitoring matrices and provides novel insights into the fetal biotransformation and accumulation of plasticizers across pregnancy.

Bioaccumulation and biotransformation of 1,2-bis (2,4,6-tribromophenoxyethane) (BTBPE) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH) in zebrafish (Danio rerio).

Despite the increasing production, use, and ubiquitous occurrence of novel brominated flame retardants (NBFRs), little information is available regarding their fate in aquatic organisms. In this study, the bioaccumulation and biotransformation of two typical NBFRs, i.e., 1,2-bis (2,4,6-tribromophenoxyethane) (BTBPE) and 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (TBECH), were investigated in tissues of zebrafish (Danio rerio) being administrated a dose of target chemicals through their diet. Linear accumulation was observed for both BTBPE and TBECH in the muscle, liver, gonads, and brain of zebrafish, and the elimination of BTBPE and TBECH in all tissues followed pseudo-first-order kinetics, with the fastest depuration rate occurring in the liver. BTBPE and TBECH showed low bioaccumulation potential in zebrafish, with biomagnification factors (BMFs) < 1 in all tissues. Individual tissues' function and lipid content are vital factors affecting the distribution of BTBPE and TBECH. Stereoselective accumulation of TBECH enantiomers was observed in zebrafish tissues, with first-eluting enantiomers, i.e. E1-α-TBECH and E1-ß-TBECH, preferentially accumulated. Additionally, the transformation products (TPs) in the zebrafish liver were comprehensively screened and identified using high-resolution mass spectrometry. Twelve TPs of BTBPE and eight TPs of TBECH were identified: biotransformation pathways involving ether cleavage, debromination, hydroxylation, and methoxylation reactions for BTBPE and hydroxylation, debromination, and oxidation processes for TBECH. Biotransformation is also a vital factor affecting the bioaccumulation potential of these two NBFRs, and the environmental impacts of NBFR TPs should be further investigated in future studies. The findings of this study provide a scientific basis for an accurate assessment of the ecological and environmental risks of BTBPE and TBECH.

Maternal hair segments reveal metal(loid) levels over the course of pregnancy: a preliminary study in Southern China.

Characterization of metal(loid) variation during pregnancy and identification of the affecting factors are important for assessing pregnancy exposures in epidemiological studies. In this study, maternal hair was collected in three segments (each 3 cm) from pregnant women in Guangzhou, China. Ten metal(loid)s, including six essential trace metal(loid)s and four toxic trace metal(loid)s, were analyzed to investigate the levels of various metal(loid)s during pregnancy and the factors that influence them. Strong pairwise correlations were observed between manganese (Mn), cobalt (Co), and vanadium (V), between selenium (Se), arsenic (As), and antimony (Sb), and between cadmium (Cd) and lead (Pb). All metal(loid)s except for Se, Mn, and Co showed strong correlations among the three hair segments, and most of the metal(loid)s had good reproducibility, with intraclass correlation coefficients (ICCs) ranging from 0.510 to 0.931, except for As (ICC = 0.334), Mn (ICC = 0.231), and Co (ICC = 0.235). Zn levels decreased, while Sb increased, in maternal hair during pregnancy. Maternal sociodemographic characteristics and dietary intake affected metal(loid) levels in maternal hair. These results provide foundational data for using maternal hair segmental analysis to evaluate exposure variation to metal(loid)s during pregnancy and the potential factors associated with them.

Spatial distribution, impact factors, and potential health implications of trace elements in human hair from capital residents in China.

We analyzed the levels, spatial distribution, impact factors, source apportionment, and potential health implications of trace elements (V, Zn, Cu, Mn, Ni, Mo, and Co) in 1202 human hair samples of urban residents aged 4-55 from 29 cities in China. The median values of seven trace elements in hair were found in the following increasing order: Co (0.02 µg/g) < V (0.04 µg/g) < Mo (0.05 µg/g) < Ni (0.32 µg/g) < Mn (0.74 µg/g) < Cu (9.63 µg/g) < Zn (157 µg/g). The spatial distribution of these trace elements in the hair from the six geographical subdivisions varied depending on the exposure sources and impact factors. Principal component analysis (PCA) revealed that Cu, Zn, and Co in the hair samples of urban residents were primarily derived from food, whereas V, Ni, and Mn were attributed to industrial activities and food. Majority of the hair samples (up to 81%) from North China (NC) exceeded the recommended value for V content, whereas up to 59.2%, 51.3%, and 31.6% samples from Northeast China (NE) exceeded the recommended values for Co, Mn, and Ni contents, respectively. The levels of Mn, Co, Ni, Cu, and Zn were significantly higher in female hair than those in male hair, whereas the levels of Mo were higher in male than in female hair (p < 0.01). Furthermore, significantly higher Cu/Zn ratios were observed in the hair of male residents than those in the female residents (p < 0.001), indicating a higher health risk for male residents.

Typical organic contaminants in hair of adult residents between inland and coastal capital cities in China: Differences in levels and composition profiles, and potential impact factors.

The growing of urbanization, industrialization, and agricultural production have resulted in the increasing contamination of typical organic contaminants (OCs) in China. However, data on differences in exposure characteristics of typical OCs between the coastal and inland cities among residents in China are limited. In this study, hair samples were collected from adult residents in 10 and 17 provincial capital cities in coastal and inland China, respectively, to investigate the differences in the levels and composition profiles of typical OCs. The potential factors impacting the human exposure to OCs were also examined based on the relationship among the hair OC levels and the population characteristics and statistical indicators. The median concentrations of dichlorodiphenyltrichloroethane's (DDTs), polybrominated diphenyl ethers (PBDEs), and organophosphorus flame retardants (PFRs) in hair of coastal urban residents were 3.64, 5.58, and 268 ng/g, respectively, while their concentrations in samples from inland urban residents were 1.84, 3.85, and 202 ng/g, respectively. Coastal residents showed significantly higher hair OC concentrations than inland residents (p < 0.05). BDE209 and p,p'-DDE were the predominant chemicals for PBDEs and DDTs, respectively, in both coastal and inland cities. Tris(2-chloroisopropyl) phosphate (TCIPP) was the dominant PFR in coastal residents' hair, while triphenyl phosphate (TPHP) was the major PFR in inland residents' hair, possibly owing to the different usages of the PFRs. Significant gender differences were observed in the levels and composition profiles of OCs (p < 0.05). The levels of p,p'-DDE and TCIPP were significantly related to the gross domestic product (GDP), gross secondary industry product, and the per capita consumption of aquatic products (p < 0.05). This study provides scientific data for evaluating human exposure to OCs in urban residents at a large scale and its associations with statistical indicators including urbanization, industrialization, agricultural production, and diet in China.

Fetal exposure to organic contaminants revealed by infant hair: A preliminary study in south China.

Fetal exposure to multiple organic contaminants (OCs) is a public concern because of the adverse effects of OCs on early life development. Infant hair has the potential to be used as an alternative matrix to identify susceptible fetuses, owing to its reliability, sensitivity, and advantages associated with sampling, handling, and ethics. However, the applicability of infant hair for assessing in utero exposure to OCs is still limited. In this study, 57 infant hair samples were collected in Guangzhou, South China, to evaluate the levels and compositions of typical OCs in the fetus. Most of the target OCs were detected in infant hair, with medians of 144 µg/g, 17.7 µg/g, 192 ng/g, 46.9 ng/g, and 1.36 ng/g for phthalate esters (PAEs), alternative plasticizers (APs), organophosphorus flame retardants (OPFRs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs), respectively. Meanwhile, paired maternal hair (0-9 cm from the scalp) was collected to examine the associations between maternal and infant hair for individual compounds. Low-brominated PBDEs tended to deposit in infant hair, with median concentrations approximately two times higher than those in maternal samples. Levels of PBDEs and 4,4'-dichlorodiphenyldichloroethylene (p,p'-DDE) in paired maternal and infant hair showed strong positive correlations (p < 0.05), while most plasticizers (PAEs and APs) were poorly correlated between paired hair samples. Exposure sources were responsible for the variation in correlation between OC levels in the paired infant and maternal samples. Crude relationships between fetal exposure to OCs and birth size were examined using the Bayesian kernel machine regression (BKMR) model. BDE-28 was found to be adversely associated with the birth size. This study provides referential information for evaluating in utero exposure to OCs and their health risks based on infant hair.

Tissue-specific and stereoselective accumulation of Dechlorane Plus isomers in two predator fish in a laboratory feeding study.

The tissue-specific bioaccumulation of Dechlorane Plus (DP) isomers was investigated in two predator fish species (redtail catfish, RF; and oscar fish, OF) that were feeding on tiger barb (TB), which was exposed to syn-DP and anti-DP isomers. The biotransformation potential of DP isomers was examined by in vitro metabolism using fish liver microsomes. No difference in accumulation behaviors of DP isomers was observed between RF and OF, and the accumulation of both syn- and anti-DP isomers exhibiting a linear increase trend with the exposure time in all fish tissues. The assimilation efficiencies and depuration rates for syn-DP and anti-DP were determined to be the highest in the liver. Biomagnification factors (BMFs) for both syn-DP and anti-DP were higher than one in the serum and gastrointestinal tract of fish, whereas were less than one in the other tissues. The wet-weight concentrations of DP isomers in tissues were significantly correlated with the lipid contents in both fish species, indicating that the tissue distribution of DP isomers occurred through passive diffusion to the lipid compartments in vivo. Tissue-specific compositions of DP isomers were observed, with anti-DP selectively accumulating in the liver, gonad, serum, and gills, whilst syn-DP in the carcass and GI tract. However, after being normalized of all tissues, the fish showed no selective accumulation of DP isomers during the exposure period, and selective accumulation of syn-DP was observed during the depuration period. No potential DP metabolites were detected in the fish tissues and in vitro metabolism systems. The main cause of this stereoselective DP isomer accumulation could have been the selective excretion of anti-DP isomer through the fish feces.

Efficiency, by-product valorization, and pollution control of co-pyrolysis of textile dyeing sludge and waste solid adsorbents: Their atmosphere, temperature, and blend ratio dependencies.

This study aimed to quantify the co-pyrolytic synergistic effects of textile dyeing sludge (TDS) and waste biochar (WBC) for an optimal utilization of secondary resources and to mitigate environmental pollution and waste volume. TDS and WBC had a strong synergistic effect between 800 and 900 °C in the CO2-assisted atmosphere. With the increased TDS fraction, NH3 emission fell significantly regardless of the atmosphere type. The CO2 atmosphere changed S in TDS char and released SO2 in the range of 800-1000 °C. With the temperature rise, an unstable N structure turned into a more stable heterocyclic N structure in the CO2 and N2 atmospheres. Regardless of the atmosphere type and temperature, the C-containing functional groups in co-pyrolytic biochar existed mainly as C-C/C-H. In the CO2 atmosphere, inorganic S, aliphatic S, and thiophene S in the co-pyrolytic biochar disappeared and became more stable sulfones. The co-pyrolysis inhibited the formation of S-containing compounds. The retention ability of the co-pyrolytic biochar peaked for most of the heavy metals in the N2 atmosphere but was better for Pb and Zn in the CO2 than N2 atmosphere. Simultaneous optimization showed the co-pyrolysis of 10% TDS and 90% WBC at above 950 °C in the N2-CO2 or CO2 atmosphere as the optimal operational settings combined.

Levels, Spatial Distribution, and Impact Factors of Heavy Metals in the Hair of Metropolitan Residents in China and Human Health Implications.

Chronic exposure to low levels of heavy metals threatens human health. However, few studies evaluated the health effects and spatial distributions of chronic exposure to heavy metals in metropolitan residents throughout mainland China using unified sampling methods and evaluation indicators at the national level. Here, the concentrations and spatial distributions of heavy metals (As, Cd, Cr, Sb, Pb, and Hg) in the hair of 1202 metropolitan residents from mainland China were analyzed, and differences in age and sex were evaluated. Most target metals exhibited higher concentrations in the hair of residents from South Central China. Generally, male hair had higher As and Se concentrations, whereas female hair had higher Cd and Pb levels (p < 0.05). A significant pairwise correlation existed between most metals in hair, especially Cd-Pb (r = 0.638, p < 0.05). The Se/heavy metal molar ratio is used as an indicator to assess the detoxification ability. The results demonstrated that protecting metropolitan residents in South Central China from heavy metals in their daily life is crucial, particularly for Hg, Pb, and Cr with Se/(Hg, Pb, or Cr) molar ratios < 1. This is the first study to comprehensively consider the antagonistic effects of Se and heavy metals using the molar ratio of Se/heavy metals to evaluate health implications and propose health management policies for metropolitan residents in China.

Antibiotics in wastewater from multiple sources and surface water of the Yangtze River in Chongqing in China.

Antibiotic contamination attracts growing concerns because of their deleterious effects on the ecosystem and human health. In this study, 43 antibiotics in wastewater from a variety of sources and water of the Yangtze River in Chongqing City in western China were measured. Thirty compounds were detected, and their concentrations were highest in leachates from the municipal solid waste treatment facilities (landfills and incineration plants) with total concentrations of 3584-57,106 ng/L. The total concentrations in influents of municipal and industrial wastewater treatment plants (WWTPs) were comparable (401-7994 ng/L versus 640-8945 ng/L). The concentrations in raw sewage from swine farms (with a total of 10,219-39,195 ng/L) and poultry farms (1419-36,027 ng/L) were noticeably higher than those from other farms (54.0-5516 ng/L). Fluoroquinolones were the dominant antibiotics contributing over 50% in all the sources, and sulfonamides and imidazole fungicides contributed 3.2-34%, whereas tetracyclines and macrolides had minor contributions. The overall antibiotic removal rates were highest in solid waste treatment facilities (88% on average), comparable between municipal and industrial WWTPs (61%), and lowest in animal farms (39%). The mass loads to the investigated municipal WWTPs via influent wastewater ranged from 7.80 to 1531 kg/year (53.2-2482 µg/day per capital). The influent mass loads to the industrial WWTPs and farms were 3.7-50 kg/year and 0.9-5437 g/year, respectively. We estimated that the mass inventories of antibiotics from these sources to the environment via effluent discharges were approximately 2044 kg for municipal WWTPs, 61 kg for industrial WWTPs, and 34 kg for animal farms in the whole city. Antibiotic concentrations in the Yangtze River water were substantially low (< 492 ng/L, with a mean of 57.8 ng/L) suggesting dissipation during the movement.

Short-term variability in levels of urinary phosphate flame retardant metabolites in adults and children from an e-waste recycling site.

In the present study, urine samples (n = 258) were collected from adults (n = 42) and children (n = 22) in an electronic waste (e-waste) recycling site. The concentrations and compositions of six di-esters, or the metabolites of phosphate flame retardants (PFRs), were measured at different time points on consecutive days. Bis(2-chloroethyl) phosphate (BCEP), dibutyl phosphate (DBP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and diphenyl phosphate (DPHP) were detected in more than 50% of urine samples. The median concentrations of BCEP, DBP, BDCIPP, and DPHP were 2.43-4.80, 0.09-2.65, 0.46-0.89, and 0.66-1.83 ng/mL in adult urine samples, respectively. For children, the median concentrations of BCEP, DBP, BDCIPP, and DPHP were 1.23, 0.08, 0.06, and 0.29 ng/mL in morning urine samples, and 1.86, 0.12, 0.14, and 0.27 ng/mL in nightfall urine samples, respectively. Nightfall urine had generally higher levels of di-esters than those in morning urine for both adults and children (p < 0.05). Children had significantly lower concentrations of di-esters than adults, indicating the occupational exposure risks of PFRs for adults. Significant correlations were observed in levels of BDCIPP (3 out of 6 groups of samples) and DPHP (2 out of 6 groups of samples) in couples (p<0.05). Significant correlations between parents and boys were only observed in BCEP levels in nightfall urine samples, and in DBP levels in morning urine samples (p<0.05). The results suggest that di-ester concentrations in e-waste recycling workers are highly variable depending on the time that samples are collected, which could further influence the estimation of human exposure to PFRs.

Measurement of Dioxin Emissions from a Small-Scale Waste Incinerator in the Absence of Air Pollution Controls.

Polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/Fs) emissions from basic small-scale waste incinerators (SWI) may cause health risks in nearby people and are thus subject to stringent regulations. The aim of this study was to evaluate PCDD/F emission and reduction of a basic SWI in the absence of air pollution controls (APCs). The results indicated that the stack gas and fly ash presented average PCDD/F levels and emission factors of 3.6 ng international toxic equivalent (I-TEQ)/Nm³ and 189.31µg I-TEQ/t and 6.89 ng I-TEQ/g and 137.85µg I-TEQ/t, respectively, much higher than those from large municipal solid waste incinerators (MSWI). PCDD/Fs congener fingerprints indicated that de novo synthesis played a dominant role in the low-temperature post-combustion zone and increased the presence of high-chlorine substituted congeners. On the basis of the emission factor 327.24 µg I-TEQ/t-waste, approximately 3000 g I-TEQ dioxins might be generated in total through basic SWIs and open burning. After refitting an SWI by adding activated carbon injection with a bag filter (ACI+BG), the PCDD/F emissions decreased to mean values of 0.042 ng I-TEQ/Nm³, far below the standard of 0.1 ng I-TEQ/Nm³, and the removal efficiency reached 99.13% in terms of I-TEQ. Therefore, it is entirely feasible to considerably reduce PCDD/F emissions by refitting basic SWI, which is positive for the future development of rural solid waste (RSW (RSW) disposal by SWI.

[Liver and Kidney Function of E-waste Dismantling Workers and Potential Influencing Factors].

High levels of exposure to heavy metals and persistent organic pollutants (POPs) by e-waste dismantling workers has attracted increasing attention, but the health conditions of the workers are seldom reported. The liver and kidney functions of the workers were studied by comparing the blood indicators of the worker group with those of the control group. Moreover, factors affecting the liver and kidney functions, such as the sexuality, age, and working time, were identified using correlation analysis. The ratio of aspartate transaminase and alanine aminotransferase (AST/ALT) and the direct bilirubin (DBIL) of the workers were significantly lower than the control group but the abnormal rate of liver and kidney remained the same in both groups. The abnormal rates of liver and kidney were higher in men than in women. ALT, AST/ALT, and urea nitrogen (BUN) increased with age while creatinine (CREA) increased with working time. The factors of liver and kidney damage caused by POPs and DBIL can be used as the indicators of the damage caused by multi-factors.

Urinary metabolites of phosphate flame retardants in workers occupied with e-waste recycling and incineration.

Urinary metabolites of phosphate flame retardants (PFRs) were determined in workers from an electronic waste (e-waste) recycling site and an incineration plant, in order to assess the PFR exposure risks of workers occupied with e-waste recycling and incineration. Bis(2-chloroethyl) phosphate (BCEP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), and diphenyl phosphate (DPHP) were the most frequently detected chemicals (82-93%). The median concentrations of BCEP, BDCIPP, and DPHP were 1.77, 0.23, and 0.70 ng/mL, and 1.44, 0.22, and 0.11 ng/mL in samples from the e-waste site and the incineration plant, respectively. Dibutyl phosphate (DBP) was detected in all samples from the incineration plant, with a median level of 0.30 ng/mL. The concentrations of BDCIPP (r = -0.31, p < 0.05) were significantly correlated with the occupational exposure time rather than age in workers from the e-waste site. Negative and significant correlations were also observed between the concentrations of BCEP (r = -0.42, p < 0.05), BDCIPP (r = -0.37, p < 0.05), and DPHP (r = -0.37, p < 0.05) and occupational exposure time rather than age in workers from the incineration plant. No gender differences were observed in levels of PFR metabolites in urine samples (p > 0.05). Concentrations of BDCIPP in female were significantly correlated with occupational exposure time (r = -0.507, p < 0.01). Concentrations of PFR metabolites in male were not significantly correlated with age or occupational exposure time (p > 0.05). Overall, the workers with occupational exposure to PFRs had different profiles of urinary PFR metabolites. The age, occupational exposure time, and gender seemed not to be main factors mediating the exposure to PFRs for workers occupied with e-waste recycling and incineration.

Emission characteristics of toxic pollutants from an updraft fixed bed gasifier for disposing rural domestic solid waste.

Gasification has gained advantage as an effective way to dispose domestic solid waste in mountainous rural of China. However, its toxic emissions such as PCDD/Fs and heavy metals, as well as their potential environmental risks, were not well studied in engineering application. In this study, an updraft fixed bed gasifier was investigated by field sampling analysis. Results showed that low toxic emissions (dust, SO2, NOx, HCl, CO, H2S, NH3, PCDD/Fs and heavy metals) in the flue gas were achieved when the rural solid waste was used as feedstock. The mass distribution of heavy metals showed that 94.00% of Pb, 80.45% of Cu, 78.00% of Cd, 77.31% of Cr, and 76.25% of As were remained in residual, whereas 86.58% of Hg was found in flue gas. The content of PCDD/Fs in the flue gas was 0.103 ngI-TEQ·Nm-3, and the total emission factor of PCDD/Fs from the gasifier was 50.04 µgI-TEQ·t-waste-1, among which only 0.04 µgI-TEQ·t-waste-1 was found in the flue gas. The total output of PCDD/Fs was1.89 times as high as input, indicting the updraft fixed bed gasifier increased emission of PCDD/Fs during the treatment domestic solid waste. In addition, the distribution characteristics of PCDD/Fs congeners reflected that PCDD/Fs was mainly generated in the gasification process rather than the stage of flue gas cleaning, suggesting the importance to effectively control the generation of PCDD/Fs within the gasifier chamber in order to obtain a low PCDD/Fs emission level.

Indoor airborne particle sources and outdoor haze days effect in urban office areas in Guangzhou.

To identify the sources of PM2.5 pollutants in work environments and determine whether the air quality inside an office was affected by a change in outdoor pollution status, concurrent indoor and outdoor measurements of PM2.5 were conducted at five different office spaces in the urban center of Guangzhou on low pollution days (non-episode days, NEDs), and high pollution days (haze episode days, EDs). Indoor-outdoor relationships between the PM2.5 mass and its chemical constituents, which included water-soluble ions, carbonaceous species, and metal elements, were investigated. A principle component analysis (PCA) was performed to further confirm the relationship between the indoor and outdoor PM2.5 pollution. The results reveal that (1) Printing and ETS (Environmental tobacco smoking) were found to be important office PM2.5 sources and associated with the enrichment of SO42-, OC, EC and some toxic metals indoors; (2) On EDs, serious outdoor pollution and higher air exchange rate greatly affected all studied office environments, masking the original differences of the indoor characteristics (3) Fresh air system could efficiently filter out most of the outside pollutants on both NEDs and EDs. Overall, the results of our study suggest that improper human behavior is associated with the day-to-day generation of indoor PM2.5 levels and sporadic outdoor pollution events can lead to poor indoor air quality in urban office environments. Moreover, fresh air system has been experimentally proved with data as an effective way to improve the air quality in office.

[Possible Sources of PCDD/Fs in Atmosphere of a Certain District in Guangdong].

This paper analyzed 17 polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) by HRGC/HRMS in the flue gas of a certain municipal solid waste incinerator(MSWI) and its surrounding air and other possible sources in Guangdong. It discussed the feature of homologs and main toxic monomers in all samples. It also investigated the relationship among surrounding area, MSWI and possible sources using principle component analysis (PCA) and cluster analysis. The results showed that the concentration of PCDD/Fs was higher in the flue gas than the ambient air, moreover non-effect suffered by prevailing wind direction. The possible sources might be tyre factory and open burning based on spot survey. The concentration of PCDD/Fs was lower in tyre factory than upwind station, but higher at open burning spot than outdrop monitoring station. The analysis of homologs showed that OCDD, 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8-HpCDF were the main materials in the flue gas and air, meanwhile OCDF was also found in atmosphere. There was similar feature of 17 PCDD/Fs between surrounding monitoring station and tyre factory, and the same between flue gas and open burning. The further analysis showed that the linearly dependent coefficients of 1,2,3,7,8-PeCDD and 2,3,4,6,7,8-HxCDF were 0.95 and 0.75, respectively. It showed the strong correlation of two monomers in all ambient air samples. The PCA and cluster analysis showed that MSWI influenced the surrounding air, tyre factory had an impact on upwind station, and open burning had a lower effect on outdrop monitoring station.

Airborne PCDD/Fs in two e-waste recycling regions after stricter environmental regulations.

Since the 2010s, the authorities of Guangdong province and local governments have enhanced law enforcement and environmental regulations to abolish open burning, acid washing, and other uncontrolled e-waste recycling activities. In this study, ambient air and indoor dust near different kinds of e-waste recycling processes were collected in Guiyu and Qingyuan to investigate the pollution status of particles and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) after stricter environmental regulations. PM2.5 and PCDD/Fs both showed significantly reduced levels in the two regions compared with the documented data. The congener distribution and principal component analysis results also confirmed the significant differences between the current PCDD/Fs pollution characterizations and the historical ones. The estimated total intake doses via air inhalation and dust ingestion of children in the recycling region of Guiyu ranged from 10 to 32pgTEQ/(kg•day), which far exceeded the tolerable daily intake (TDI) limit (1-4pgTEQ/(kg•day). Although the measurements showed a significant reduction of the release of PCDD/Fs, the pollution status was still considered severe in Guiyu town after stricter regulations were implemented.