Distribution characteristics, air-water exchange, ozone formation potential and health risk assessments of VOCs emitted from typical coking wastewater treatment process

Impact of coking plant to heavy metal characteristics in groundwater of surrounding areas: Spatial distribution, source apportionment and risk assessments

Coking industry is a potential source of heavy metals (HMs) pollution. However, its impacts to the groundwater of surrounding residential areas have not been well understood. This study investigated the pollution characteristics and health risks of HMs in groundwater nearby a typical coking plant. Nine HMs including Fe, Zn, Mo, As, Cu, Ni, Cr, Pb and Cd were analyzed. The average concentration of total HMs was higher in the nearby area (244.27 µg/L) than that of remote area away the coking plant (89.15 µg/L). The spatial distribution of pollution indices including heavy metal pollution index (HPI), Nemerow index (NI) and contamination degree (CD), all demonstrated higher values at the nearby residential areas, suggesting coking activity could significantly impact the HMs distribution characteristics. Four sources of HMs were identified by Positive Matrix Factorization (PMF) model, which indicated coal washing and coking emission were the dominant sources, accounted for 40.4%, and 31.0%, respectively. Oral ingestion was found to be the dominant exposure pathway with higher exposure dose to children than adults. Hazard quotient (HQ) values were below 1.0, suggesting negligible non-carcinogenic health risks, while potential carcinogenic risks were from Pb and Ni with cancer risk (CR) values > 10-6. Monte Carlo simulation matched well with the calculated results with HMs concentrations to be the most sensitive parameters. This study provides insights into understanding how the industrial coking activities can impact the HMs pollution characteristics in groundwater, thus facilitating the implement of HMs regulation in coking industries.

Combined pollution of heavy metals and polycyclic aromatic hydrocarbons in non-ferrous metal smelting wastewater treatment plant: Distribution profiles, removal efficiency, and ecological risks to receiving river

Combined pollution status of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) from non-ferrous metal smelting (NFMS) industry is crucial but has not been explored. Herein, the co-distribution of HMs and PAHs in a NFMS wastewater treatment plant and the impacts on the receiving river were investigated. Cu, As, and Ni were found to be the characteristic HMs, while Acenaphthylene was the characteristic PAHs in the NFMS wastewater. The removal of HMs and PAHs in wastewater showed a strong positive correlation (R2 > 0.84, p < 0.05) with removal efficiency of 90.7 % and 94.1 %, respectively. It was estimated 547.5 kg HMs and 13.3 kg PAHs were discharged into the receiving river annually. The average concentration of HMs and PAHs in downstream was respective 1.6 and 2.7 times higher than that in upstream, and the sites near discharge outlet had significant spatial autocorrelation (p < 0.05), suggesting the discharge of NFMS wastewater had significantly influenced the receiving river. Aquatic organisms were posed to moderate chronic ecological risk (RQC > 0.1) and surrounding residents were posed to probable carcinogenic risk (TCR > 10-5). This work provides new insights into understanding the combined pollution and corresponding ecological risks from key industrial sectors globally.

Characterization of VOCs emissions and associated health risks inherent to the packaging and printing industries in Shandong Province, China

Comprehensive volatile organic compounds (VOCs) emission control is imperative to decreasing occupational health risks and environmental impact of the packaging and printing industries. In this work, we investigated the VOCs emission characteristics and concentrations of individual contaminants generated by the packaging and printing industries, with regard to various categories, processes, and geographic regions. VOCs emissions, ozone formation potential (OFP), and associated health risks were assessed at 10 representative packaging and printing firms across several cities in Shandong Province, China. Plastic packaging enterprises had the greatest levels of unorganized VOCs emissions, consisting predominantly of oxygenated volatile organic compounds (OVOCs), followed by alkanes and halocarbons. From metal and paper packaging enterprises, OVOCs, alkanes, and aromatics were significant components of unorganized VOCs emissions. Aromatics, halocarbons, and OVOCs contributed significantly to OFP in workshops. The potential carcinogenic risk associated with VOCs in the packaging and printing industries was not significant. However, according to the findings in this study, the workshop environment may provide a comparatively elevated non-carcinogenic risk attributable to ethyl acetate, isopropanol, acrolein, 1,1,2-Trichloroethane, 1,2-Dichloropropane, and naphthalene exposure. In particular, the endocrine-disrupting and genetic toxic effects caused by benzene, toluene, styrene, and naphthalene should not be overlooked. Thus, it is essential to provide precedence to the working environment conditions of workshop laborers, while also undertaking scientific and systematic measures to mitigate the detrimental impacts of VOCs on the environment and human welfare.

Aqueous VOCs in complex water environment of oil exploitation sites: Spatial distribution, migration flux, and risk assessment

Pollution of the aqueous environment by volatile organic compounds (VOCs) has caused increasing concerns. However, the occurrence and risks of aqueous VOCs in oil exploitation areas remain unclear. Herein, spatial distribution, migration flux, and environmental risks of VOCs in complex surface waters (including River, Estuary, Offshore and Aquaculture areas) were investigated at a typical coastal oil exploitation site. Among these surface waters, River was the most polluted area, and 1,2-Dichloropropane-which emerges from oil extraction activities-was the most prevalent VOC. Positive matrix factorization showed that VOCs pollution sources changed from oil exploitation to offshore disinfection activities along River, Estuary, Offshore and Aquaculture areas. Annual volatilization of VOCs to the atmosphere was predicted to be ∼34.42 tons, and rivers discharge ∼23.70 tons VOCs into the Bohai Sea annually. Ecological risk assessment indicated that Ethylbenzene and Bromochloromethane posed potential ecological risks to the aquatic environment, while olfactory assessment indicated that VOCs in surface waters did not pose an odor exposure risk. This study provides the first assessment of the pollution characteristics of aqueous VOCs in complex aqueous environments of oil exploitation sites, highlighting that oil exploitation activities can have nonnegligible impacts on VOCs pollution profiles.

Facilitation of coke gasification by coking wastewater and its degradation properties in thermochemical reactions

The thermochemical reaction between coking wastewater and gasification-coke is a new way to achieve efficient and clean use of coal and solve the problem of coking wastewater treatment in the Gansu Longdong region. To further investigate the thermochemical reaction characteristics of coking wastewater and gasification-coke, this paper explores the effect of coking wastewater on syngas production from coke gasification at 1000 °C, the degradation effect of organic pollutants in coking wastewater, the thermochemical reactivity of gasification-coke, and the reasons why wastewater promotes coke gasification and wastewater degradation. The results showed that the thermochemical reaction of coking wastewater with gasification-coke not only facilitates the improvement of syngas yield and low-level calorific value but also improves the thermochemical reactivity of gasification-coke. Notably, phenol in coking wastewater plays a major role in promoting the gasification of gasification-coke. During the thermochemical reaction, the organic pollutants in the wastewater were effectively degraded, the degradation rate of CODCr reached more than 85%, and the degradation of organic pollutants reached more than 75%. Phenol water and coking wastewater can not only improve the dispersion of the ash phase on the surface of gasification-coke, effectively inhibiting the sintering and agglomeration of the ash phase in gasification-coke, but also change the type and number of organic functional groups in gasification-coke. Therefore, coking wastewater can promote the gasification of coke. The thermochemical reaction between coke wastewater and gasification-coke can simultaneously promote coke gasification and the degradation of coke wastewater and achieve the resourceful use of coke wastewater.

Environmental and dietary exposure to 24 polycyclic aromatic hydrocarbons in a typical Chinese coking plant

Polycyclic aromatic hydrocarbons (PAHs), known for their health risks, are prevalent in the environment, with the coking industry being a major source of their emissions. To bridge the knowledge gap concerning the relationship between environmental and dietary PAH exposure, we explore this complex interplay by investigating the dietary exposure characteristics of 24 PAHs within a typical Chinese coking plant and their association with environmental pollution. Our research revealed Nap and Fle as primary dietary contaminants, emphasizing the significant influence of soil and atmospheric pollution on PAH exposure. We subjected our data to non-metric multidimensional scaling (NMDS), Spearman correlation analysis, Lasso regression, and Weighted Quantile Sum (WQS) regression to delve into this multifaceted phenomenon. NMDS reveals that dietary PAH exposure, especially within the high molecular weight (HMW) group, is common both within and around the coking plant. This suggests that meals prepared within the plant may be contaminated, posing health risks to coking plant workers. Furthermore, our assessment of dietary exposure risk highlights Nap and Fle as the primary dietary contaminants, with BaP and DahA raising concerns due to their higher carcinogenic potential. Our findings indicate that dietary exposure often exceeds acceptable limits, particularly for coking plant workers. Correlation analyses uncover the dominant roles of soil and atmospheric pollution in shaping dietary PAH exposure. Soil contamination significantly impacts specific PAHs, while atmospheric pollution contributes to others. Additionally, WQS regression emphasizes the substantial influence of soil and drinking water on dietary PAHs. In summary, our study sheds light on the dietary exposure characteristics of PAHs in a typical Chinese coking plant and their intricate interplay with environmental factors. These findings underscore the need for comprehensive strategies to mitigate PAH exposure so as to safeguard both human health and the environment in affected regions.

Occurrence of BTX and PAHs in underground drinking water of coking contaminated sites: Linkage with altitude and health risk assessment by boiling-modified models

The safety of underground drinking water has received widespread attention. However, few studies have focused on the occurrence and health risks of pollutants in underground drinking water of coking contaminated sites. In this study, the distribution characteristics, sources, and human health risks of benzene, toluene, xylene (BTX) and polycyclic aromatic hydrocarbons (PAHs) in underground drinking water from a typical coking contaminated site in Shanxi of China were investigated. The average concentrations of BTX and PAHs in coking plant (CP) were 5.1 and 4.8 times higher than those in residential area (RA), respectively. Toluene and Benzene were the main BTX, while Acenaphthene, Fluorene, and Pyrene were the main PAHs. Concentrations of BTX/PAHs were negatively correlated with altitude, revealing altitude might be an important geological factor influencing spatial distribution of BTX/PAHs. PMF model demonstrated that the BTX/PAHs pollution in RA mainly originated from coking industrial activities. Health risk assessments were conducted by a modified US EPA-based model, in which environmental concentrations were replaced by residual concentrations after boiling. Residual ratios of different BTX/PAHs were determined by boiling experiments to be 9.4-93.8 %. The average total carcinogenic risks after boiling were decreased from 2.6 × 10-6 to 1.4 × 10-6 for adults, and from 4.3 × 10-6 to 2.1 × 10-6 for children, suggesting boiling was an effective strategy to reduce the carcinogenic risks from BTX/PAHs, especially for ingestion pathway. Monte Carlo simulation results matched well with the calculated results, suggesting the uncertainty was acceptable and the risk assessment results were reliable. This study provided useful information for revealing the spatial distribution of BTX/PAHs in underground drinking water of coking contaminated sites, understanding their linkage with altitude, and also helped to more accurately evaluate the health risks by using the newly established boiling-modified models.

High-solution emission characters and health risks of volatile organic compounds for sprayers in automobile repair industries

The increasing automobile repair industries (ARIs) with spray facilities have become an important volatile organic compound (VOC) pollution source in China. However, the VOC health risk assessment for long-term exposure in ARIs has not been well characterized. In this study, though sampled VOCs from 51 typical ARIs in Beijing, the relationship between emission patterns, average daily exposure concentrations (EC), and health risks was comprehensively analyzed with the health assessment method. Results showed that concentrations of 117 VOCs from the samples ranged from 68.53 to 19863.32 μg·m-3, while the ARI operator's daily VOC inhalation EC was 11.24-1460.70 μg·m-3. The organic VOC (OVOC) concentration accounted for 73.16 ~ 94.52% in the solvent-based paint workshops, while aromatics were the main VOC component in water-based paint spraying (WPS) workshops, accounting for 70.08%, respectively. And the method of inhalation exposure health risk assessment was firstly used to evaluate carcinogenicity and non-carcinogenicity risk for sprayers in ARIs. The cumulative lifetime carcinogenic risk (LCR) for 24 sampled VOCs were within acceptable ranges, while the mean hazard index (HI) for 1 year with 44 sampled VOCs was over 1. Among them, ethyl alcohol had a high carcinogenic risk in both mixed water-based paint (MP) and solvent-based paint workshops. The mean HI associated with aromatics were 2.88E - 3 and 4.30E - 3 for 1 h in MP and WPS workshops. O-ethyl toluene and acetone are VOC components that need to be paid attention to in future paint raw materials and spraying operations. Our study will provide the important references for the standard of VOC occupational exposure health limits in ARIs.

Intermodal comparison of commuters' exposure to VOCs between public, private, and active transportation

Urban populations are exposed to a multitude of traffic-related air pollutants during daily commutes. This study assessed commuters' exposure to volatile organic compounds (VOCs) during bus, motorcycle, and bicycle commuting, and estimated the VOC inhalation dose. Benzene, toluene, ethylbenzene, and xylene (BTEX) were the main compounds detected, contributing 58 - 68% to ΣVOC (sum of the concentrations of all detected VOCs) in different travel modes. The mean ΣVOC exposure concentration was higher for motorcyclists than for cyclists and bus commuters. However, due to cyclists' higher minute ventilation rates and longer exposure time, they had the highest ΣVOC inhalation dose based on both travel time (7.09 ± 2.36 μg min-1) and distance (32.9 ± 10.8 μg km-1). Among the three travel modes, bus commuters had the lowest ΣVOC inhalation dose based on travel time (2.33 ± 1.18 μg min-1) and distance (8.91 ± 4.91 μg km-1), while motorcyclists had a moderate ΣVOC inhalation dose based on travel time (5.08 ± 1.46 μg min-1) and distance (13.4 ± 5.5 μg km-1). Health impact assessment of VOCs showed that cyclists faced the highest carcinogenic and non-carcinogenic risks, while bus commuters experienced the lowest health risk associated with VOC exposure. Our findings underscore the need to consider air quality in transportation infrastructure design and prioritize interventions to safeguard urban commuters' health, particularly cyclists, who are the most vulnerable to the adverse effects of traffic-related air pollutants.