The identification, health risks and olfactory effects assessment of VOCs released from the wastewater storage tank in a pesticide plant

Emission characteristics, environmental impacts and health risk assessment of volatile organic compounds from the typical chemical industry in China

To study the volatile organic compounds (VOCs) emission characteristics of industrial enterprises in China, 6 typical chemical industries in Yuncheng City were selected as research objects, including the modern coal chemical industry (MCC), pharmaceutical industry (PM), pesticide industry (PE), coking industry (CO) and organic chemical industry (OC). The chemical composition of 91 VOCs was quantitatively analyzed. The results showed that the emission concentration of VOCs in the chemical industry ranged from 1.16 to 155.59 mg/m3. Alkanes were the main emission components of MCC (62.0%), PE (55.1%), and OC (58.5%). Alkenes (46.5%) were important components of PM, followed by alkanes (23.8%) and oxygenated volatile organic compounds (OVOCs) (21.2%). Halocarbons (8.6%-71.1%), OVOCs (9.7%-37.6%) and alkanes (11.2%-27.0%) were characteristic components of CO. The largest contributor to OFP was alkenes (0.6%-81.7%), followed by alkanes (9.3%-45.9%), and the lowest one was alkyne (0%-0.5%). Aromatics (66.9%-85.4%) were the largest contributing components to SOA generation, followed by alkanes (2.6%-28.5%), and the lowest one was alkenes (0%-4.1%). Ethylene and BTEX were the key active species in various chemical industries. The human health risk assessment showed workers long-term exposed to the air in the chemical industrial zone had a high cancer and non-cancer risk during work, and BTEX and dichloromethane were the largest contributors.

Risk-oriented source apportionment and implications for mitigation strategies of VOCs in industrial parks: Insights from odor pollution and health risks

A typical industrial park in the upper reaches of the Yangtze River Economic Belt, which is 70 km from the Chongqing urban center, was used to investigate the occurrence and exposure of harmful volatile organic compounds (VOCs). An exposure risk method and a risk-oriented source apportionment approach were performed to assess the inhalation risks and apportion VOC sources, respectively. The quantitative relationships between risk factors and pollution sources were established, identifying key pathogenic and odorous VOCs. The quantitative emission reduction strategies were developed based on risk thresholds. Residents within the industrial parks face potential health risks due to pathogenic VOCs and nuisance odors, and workers in specific sectors experience two to six times higher risks than those in residential areas. Six risk sources were identified in the industrial park, ranked according to their contribution to VOC concentrations as follows: industrial sewage treatment (IST) (32.59 %), natural gas chemical industry (NGCI) (27.77 %), diesel vehicle exhaust (DVE) (12.04 %), pharmaceutical manufacturing industry (PMI) (11.14 %), chemical raw materials manufacturing (CRMM) (9.96 %), and iron and steel industry (ISI) (6.5 %). Among these, NGCI, IST, and CRMM were the top contributors to pathogenic risks, with contributions of 32.13 %, 29.71 %, and 21.71 % to non-carcinogenic risks, and 18.15 %, 19.87 %, and 27.99 % to carcinogenic risks, respectively. DVE produced significantly higher odor pollution compared to other sources, with intensities that were 3 to 10 times greater. The key pathogenic and odorous VOCs differ by source, resulting in varying control priorities for different VOC species. Reducing emissions from these six sources for 20 high-risk species (e.g., acrolein, 2-chlorotoluene, 1,2-dibromoethane, dichloromethane, and p-diethylbenzene) will simultaneously lower pathogenic and odor risks, with cumulative reduction rates ranging from 4.11 % to 93.75 %. This study provides quantitative control targets for VOCs from a health risk perspective, offering valuable guidance for developing risk management policies in industrial parks.

Cooperative and Bifunctional Adsorbent-Catalyst Materials for In-situ VOCs Capture-Conversion

Volatile organic compounds (VOCs) are gases that are emitted into the air from products or processes and are major components of air pollution that significantly deteriorate air quality and seriously affect human health. Different types of metals, metal oxides, mixed-metal oxides, polymers, activated carbons, zeolites, metal-organic frameworks (MOFs) and mixed-matrixed materials have been developed and used as adsorbent or catalyst for diversified VOCs detection, removal, and destruction. In this comprehensive review, we first discuss the general classification of VOCs removal materials and processes and outline the historical development of bifunctional and cooperative adsorbent-catalyst materials for the removal of VOCs from air. Subsequently, particular attention is devoted to design of strategies for cooperative adsorbent-catalyst materials, along with detailed discussions on the latest advances on these bifunctional materials, reaction mechanisms, long-term stability, and regeneration for VOCs removal processes. Finally, challenges and future opportunities for the environmental implementation of these bifunctional materials are identified and outlined with the intent of providing insightful guidance on the design and fabrication of more efficient materials and systems for VOCs removal in the future.

Determining the soil odor control area: A case study of an abandoned organophosphorus pesticide factory in China

Currently, soil odor-active substance screening and evaluation methods for contaminated sites are underdeveloped, with unclear treatment objectives and areas. Consequently, some sites suffer from odor issues during and even after remediation. This study focused on an organophosphorus pesticide factory site in Guangdong Province, China. It established a method of determining the odorant control area using a comprehensive approach combining instrumental and olfactory soil sample analyses. The main odor-active substances identified were ethylbenzene, phenol, m, p-xylene, styrene, toluene, and o-xylene, with odorant control values (the limit of odor-active substance contents) of 35.2, 28.1, 8.0, 11.3, 40.2 and 89.3 mg/kg respectively. Instrumental analysis of soil samples revealed 11 sampling points where the main odor-causing substances exceeded standard levels. Among the substances, ethylbenzene (1.48E+04 mg/kg) had the highest content, exceeding the limit up to 421-fold. Olfactory analysis indicated 14 sampling points with odor intensity surpassing the standard (OI > 2). Based on the instrumental analysis results and the odorant control value, the initial estimated odor control area (area with the risk of odor nuisance) was 5.64E+03 m2. Incorporating the olfactory analysis findings, the control area was adjusted by 1.25E+03 m2, leading to a final calculated soil odor control area of 6.89E+03 m2 for the study site. The comprehensive approach to analyzing soil samples for odor control can help evaluate the extent of soil odor pollution in contaminated sites and provide a scientific basis for effectively removing and managing odor-causing substances in soil.

VOC emitted by biopharmaceutical industries: Source profiles, health risks, and secondary pollution

The biopharmaceutical industry contributes substantially to volatile organic compounds (VOCs) emissions, causing growing concerns and social developmental conflicts. This study conducted an on-site investigation of the process-based emission of VOCs from three biopharmaceutical enterprises. In the workshops of the three enterprises, 26 VOCs were detected, which could be sorted into 4 classes: hydrocarbons, aromatic hydrocarbons, oxygen-containing compounds, and nitrogen-containing compounds. Ketones were the main components of waste gases, accounting for 44.13%-77.85% of the overall VOCs. Process-based source profiles were compiled for each process unit, with the fermentation and extraction units of tiamulin fumarate being the main source of VOC emissions. Dimethyl heptanone, vinyl acetate, diethylamine, propylene glycol methyl ether (PGME), and benzene were screened as priority pollutants through a fuzzy comprehensive evaluation system. Ground level concentration simulation results of the Gauss plume diffusion model demonstrated that the diffusivity of VOCs in the atmosphere was relatively high, indicating potential non-carcinogenic and carcinogenic risks 1.5-2 km downwind. Furthermore, the process-based formation potentials of ozone and secondary organic aerosols (SOAs) were determined and indicated that N-methyl-2-pyrrolidone, dimethyl heptanone, and PGME should be preferentially controlled to reduce the ozone formation potential, whereas the control of benzene and chlorobenzene should be prioritized to reduce the generation of SOAs. Our results provide a basis for understanding the characteristics of VOC emission by biopharmaceutical industries and their diffusion, potentially allowing the development of measures to reduce health risks and secondary pollution.

Application of Composts' Biochar as Potential Sorbent to Reduce VOCs Emission during Kitchen Waste Storage

It is expected that due to the new European Union regulation focus on waste management, managing kitchen waste will become more important in the future, especially in households. Therefore, it is crucial to develop user-friendly and odour-free containers to store kitchen waste. The study aimed to test the effectiveness of composts' biochar in reducing noxious odours and volatile organic compounds (VOCs) released during kitchen waste storage. Various amounts of compost biochar (0%, 1%, 5%, and 10%) were added to food waste samples and incubated for seven days at 20 °C. The released VOCs were analysed on days 1, 3, and 7 of the storage simulation process. The results indicated that adding 5-10% of composts' biochar to kitchen waste significantly reduced the emissions in 70% of the detected VOCs compounds. Furthermore, composts' biochar can be used to eliminate potential odour components and specific dangerous VOCs such as ethylbenzene, o-xylene, acetic acid, and naphthalene. A new composts' biochar with a unique composition was particularly effective in reducing VOCs and could be an excellent solution for eliminating odours in kitchen waste containers.

Real-time emission characteristics, health risks, and olfactory effects of VOCs released from soil disturbance during the remediation of an abandoned chemical pesticide industrial site

Volatile organic compounds (VOCs) released along with soil disturbance during the remediation of abandoned industrial sites have attracted great attention due to their possible toxicity and odour. However, the real-time emission characteristics of these VOCs and their subsequent effects on health and olfaction are less understood. In this study, the gaseous VOCs released from soil disturbance by excavators and drilling rigs at an abandoned chemical pesticide plant were monitored online with a laboratory-built single photoionization time-of-flight mass spectrometer (SPI-TOFMS). Twelve main VOCs with total mean concentrations ranging from 2350 to 3410 μg m-3 were observed, with dichloromethane (DCM) having a significant contribution. The total concentrations of the remaining 11 VOCs increased substantially during soil disturbance, with the total mean concentrations increasing from 18.65-39.05 to 37.95-297.94 μg m-3 and those of peak concentrations increasing from 28.46-58.97 to 88.38-839.13 μg m-3. This increase in VOC concentrations during soil disturbance leads to an enhanced heath risk for on-site workers. The distinctive difference between the mean and peak concentrations of VOCs indicates the importance of using mean and peak concentrations, respectively, for risk and olfactory evaluation due to the rapid response of the human nose to odours. As a result, the cumulative noncarcinogenic risk at the relatively high pollutant plot was higher than the occupational safety limit, while the total carcinogenic risks at all monitored scenarios exceeded the acceptable limit. Among the VOCs investigated, DCM and trichloroethylene (TCE) were determined to be crucial pollutants for both noncarcinogenic and carcinogenic risks of VOCs. With regard to olfactory effects, organic sulphides, including dimethyl disulphide (DMDS), dimethyl sulphide (DMS), and dimethyl trisulphide (DMTS) were identified as dominant odour contributors (78.28-92.11%) during soil disturbance.

Development of an electronic nose to characterize water quality parameters and odor concentration of wastewater emitted from different phases in a wastewater treatment plant

For public health consideration, it is important to ensure the wastewater discharged from wastewater treatment plant is within the regulatory limits. This problem can be effectively solved by improving the accuracy and rapid characterization of water quality parameters and odor concentration of wastewater. In this paper, we proposed a novel solution to realize the precisive analysis of water quality parameters and odor concentration of wastewater by the electronic nose device. The main work of this paper was divided into three steps: 1) recognizing wastewater samples qualitatively from different sampling points, 2) analyzing the correlation between electronic nose response signals and water quality parameters and odor concentration, and 3) predicting the odor concentration and water quality parameters quantitatively. Combined with different feature extraction methods, support vector machine and linear discriminant analysis were applied as classifiers to recognize samples at different sampling points, which reported the best recognition rate of 98.83%. Partial least squares regression was applied to complete the second step, and R² was reaching 0.992. As for the third step, ridge regression was used to predict water quality parameters and odor concentration with the RMSE less than 0.9476. Thus, electronic noses can be applied to determine water quality parameters and odor concentrations in the effluent discharged from wastewater plants.

Generation characteristics and spreading risk of VOCs released from a biological fermentation pharmaceutical factory

Pharmaceutical factories produce a large amount of volatile organic compounds (VOCs), which may pose a potential health threat to the environment, workers, and nearby residents. Sampling points were set up in the tylosin biological fermentation workshop (FW) and sewage treatment station (STS) of a pharmaceutical factory in a central city in northern China to collect VOCs and study their generation characteristics and diffusion. The results indicated that with the increase in fermentation time, VOC production decreased gradually, and the decline was rapid. The main VOCs produced by the FW are oxygen-containing organics and nitrogen-containing organics including 1-heptyladehyde (8.86 × 10² mg m^-3), 1-methyl-2-pyrrolidone (6.36 × 10² mg m^-3) and benzene (5.85 × 10² mg m^-3). The STS mainly produces nitrogen-containing organics and oxygen-containing organics including 1-methyl-2-pyrrolidone (3.38 × 10³ mg m^-3), diethyl amine (9.60 × 10² mg m^-3) and methyl ethyl ketone (2.98 × 10² mg m^-3). VOCs produced by biopharmaceutical factories can diffuse for a long distance in the atmosphere. The highest concentration of chlorinated organic compounds can spread to 11.43 kilometers in the horizontal direction and 3 kilometers in the vertical direction. Acetaldehyde, butyraldehyde, diethylamine, butyl acetate and methyl ethyl ketone are odorous gases detected in the FW and STS, respectively. Benzene, carbon tetrachloride and acetaldehyde are the main carcinogenic VOCs produced in the fermentation process of tylosin. The research elucidated production characteristics, diffusion and health risks of VOCs in the FW, which provided a reference for the control of VOCs.

Emission behavior and impact assessment of gaseous volatile compounds in two typical rural domestic waste landfills

Landfill sites are sources of gaseous volatile compounds. The dumping area (LDA) and leachate storage pool (LSP) of two typical rural domestic waste landfill sites in north China (NLF) and southwest China (SLF) were investigated. We found that 45, 46, 61 and 68 volatile organic compounds (VOC) were present in the air of NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. And there were 27, 29, 35 and 37 kinds of odorous compounds being detected. Oxygenated compounds (>48.88%), chlorinated compounds (>6.85%), and aromatics (>5.46%), such as organic acid, 1-chlorobutane, and benzene, were the most abundant compounds in both landfills. The SLF-LDA had the highest olfactory effect, with a corresponding total odor activity value of 29,635.39. The ozone-formation potential analysis showed that VOCs emitted from SLF landfills had significantly higher potential for ozone formation than those from NLF landfills, with ozone generation potentials of 166.02, 225.86, 2511.82, and 1615.99 mg/m³ for the NLF-LDA, NLF-LSP, SLF-LDA, and SLF-LSP, respectively. Higher chronic toxicity and cancer risk of VOCs were found in the SLF according to method of Risk Assessment Information System. Based on the sensitivity analysis by the Monte Carlo method, concentrations of benzene, propylene oxide, propylene, trichloroethylene, and N-nitrosodiethylamine, along with exposure duration, daily exposure time, and annual exposure frequency, significantly impacted the risk levels. We provide a scientific basis, which reflects the need for controlling and reducing gaseous pollutants from landfills, particularly rural residential landfills, which may improve rural sanitation.

Degradation kinetics of aromatic VOCs polluted wastewater by functional bacteria at laboratory scale

Reaction kinetics in biodegradation process is the basis and key of bioremediation technology, which can be used to predict the interaction between microorganisms and environmental states in the system. In this study, the kinetic model (Monod, Moser, Tessier and Cotonis) and kinetic parameters of aerobic biodegradation of functional bacteria in simulated wastewater polluted by aromatic volatile organic compounds (VOCs) were determined by shaking flask experiment. Monod, Moser, Tessier and Contois models were used to fit the experimental data and determine the kinetic parameters based on nonlinear regression analysis. Experimental results demonstrated that the removal rate of aromatic VOCs at 72 h was between 34.78 and 99.75% depending on the initial concentration of aromatic VOCs. The specific growth rate μ and degradation rate q increased with the increase of substrate concentration. The model of Monod, Moser and Tessier could be used to simulate microbial growth and substrate degradation in simulated aromatic VOCs polluted wastewater. Then the model and corresponding kinetic parameters were used to predict the limit concentration of biodegradation and provide theoretical support for the subsequent dynamic simulation and field engineering.

Migration and transformation of main components during perishable waste bio-drying process

Bio-drying can significantly reduce the moisture content of waste. The factors, functional microorganisms, and the transformation of main components were investigated during bio-drying of perishable waste. This study provides a scientific basis for the improvement of the bio-drying process and the necessity for secondary pollutant control. Reaction temperature and microbial biomass were main factors during the bio-drying process. The ideal bio-drying conditions included an initial temperature above 20 °C, intermittent ventilation, and appropriate microbial inoculation. The main microorganisms included Alcaligenes, Aquamicrobium, and Brevundimonas. From each gram of the carbonaceous, nitrogenous, sulfur-containing compounds, and phosphorus-containing substances in the perishable waste, approximately 0.74 g, 0.66 g, 0.40 g, and 0.94 g, respectively, were transferred as gas-phase products; consisting mainly of ammonia and volatile organic compounds: 2-heptanone, dimethyl heptanone, and benzene. In the leachate, the respective amounts of the carbonaceous, nitrogenous, sulfur-containing compounds, and phosphorus-containing substances were 3.20 × 10^-3 g, 4.08 × 10^-3 g, 0.33 g, and 9.52 × 10^-3 g, while those of the residual substances remaining in solid were 0.26 g, 0.33 g, 0.28 g, and 0.05 g.

Emission of volatile organic compounds (VOCs) from application of commercial pesticides in China

Applying pesticides can result in emissions of volatile organic compounds (VOCs), but little is known about VOC emission characteristics and the quantities in particular regions. We investigated the use of pesticides in China based on a large-scale survey of 330 counties in 31 provinces and evaluated the national pesticide VOC emission potentials based on thermogravimetric analysis of 1930 commercial pesticides. The results showed that herbicides were the most extensively used pesticide category in China, accounting for 43.47%; emulsifiable concentrate (EC), suspension concentrate, and wettable powder were the dominant pesticide formulations, with proportions of 26.75%, 17.68%, and 17.31%, respectively. The VOC emission potential coefficient (EP) of the liquid formulations was higher than the solid formulations, and the maximum mean EP was 45.59% for EC and the minimum was 0.76% for WP. Among 437 high-VOC pesticide products used in China, EC accounted for 83.52%, and 16.93% of those contained abamectin. The total VOC emissions derived from commercial pesticides in China were 280 kt (kilotons) in 2018, and 65.35% of the contribution was derived from EC. Shandong, Hunan, and Henan were the three provinces with the highest pesticide VOC emissions (>21 kt/y). The emission rate of VOCs from pesticides was 24.80 t/d in China, which was higher than in San Joaquin Valley, California. These findings suggest that some comprehensive measures (e.g., perfecting pesticide management policy, strict supervision for pesticide production and use, and strengthening pesticide reduction publicity) should be taken to reduce VOC emissions from pesticide applications.

Dispersion, olfactory effect, and health risks of VOCs and odors in a rural domestic waste transfer station

The impact of odorous gases emitted from refuse transfer stations has always been a concern raised by the surrounding residents. The emitted volatile organic compounds (VOCs) and odors were investigated in a rural solid waste transfer station (RSWTS) located in Southwest China. A total of 70 VOCs were identified and quantified. The total VOCs (TVOCs) concentrations varied from 848.38 to 31193.24 μg/m³. Inorganic odor and greenhouse gases concentrations ranged from 39.11 to 470.14 μg/m³ and 1.03-525.42 μg/m³, respectively. Oxygenated compounds contributed the most (58.25%) to the VOCs. Among the oxygenated compounds, ketones, esters, and ethers were the dominant categories, accounting for 67.5%, 12.70%, and 11.85%, respectively. The key odorants included propionaldehyde, hexanaldehyde, propionic acid, acetaldehyde, and disopropyl ether. N-nitrosodiethylamine, acrylonitrile, and 1,3-Butadiene were the three main carcinogens that pose considerable risk to human health. Allyl chloride was the most non-carcinogenic pathogen among the VOCs detected in RSWTS. With diffusion in the downwind direction, the concentration of VOCs decreased gradually, and their risks weakened accordingly. At the sampling site of RSWTS-10, located 100 m away from RSWTS, acrylonitrile and 1,3-Butadiene still presented an unacceptable carcinogenic risk to human health. This study provides new data for assessing the emission characteristics, olfactory effects, and health risks of trace VOCs, especially those released from RSWTS.

Potent necrosis effect of methanethiol mediated by METTL7B enzyme bioactivation mechanism in 16HBE cell

Methanethiol is a widely existing malodorous pollutant with health effects on the human population. However, the cytotoxicity mechanism of methanethiol in vitro and its metabolic transformation (bioactivation or detoxification) have not been fully elucidated. Herein, the metabolites of methanethiol during cell culture and the cytotoxicity of methanethiol in human bronchial epithelial (16HBE) cells were investigated. Results indicate that methanethiol (10-50 μM) was partially converted into dimethyl sulfide, mainly catalyzed by thiol S-methyltransferase in the 16HBE cells, and then it induced potent cytotoxicity and cell membrane permeability. Moreover, methanethiol induced intracellular reactive oxygen species (ROS) up to 50 μM and further activated the tumor necrosis factor (TNF) signaling pathway, which eventually led to the decline in the mitochondrial membrane potential (MMP) and cell necrosis. However, all these effects were significantly alleviated with gene silencing of the methyltransferase-like protein 7B (METTL7B). These results indicate that methanethiol may induce cell necrosis in human respiratory tract cells mainly mediated by S-methyltransferase with interfering TNF and ROS induction. Non-target metabolomics results suggest that methanethiol potently affects expression of endogenous small molecule metabolites in 16HBE cells. To some extent, this work shows the possible conversion path and potential injury mechanism of human respiratory tract cells exposed to methanethiol.

Human health risk assessment and distribution of VOCs in a chemical site, Weinan, China

The study assessed the volatile organic compound (VOC) pollution characteristics in a chemical site in Weinan, China. The results indicated that chloroform, benzene, trichloroethylene, 1,2-dichloroethane, ethylbenzene, 1,2-dichloropropane, and 1,2,3-Trichloropropane exceeded the soil standard limit for soil contamination of development land (GB36600, PRC). Using pollution index, ambient severity, and correlation coefficient revealed industrial production and relocation activities as sources of VOCs contamination in the site. The carcinogenic risk assessed by human exposure to site VOCs through ingestion, respiration, exposure, etc., exceeded the potentially acceptable level (1.0 × 10−6). 1,2,3-trichloropropane has the highest carcinogenic risk across all pathways, regions, and populations. The long-term exposure and emission of VOCs in the investigated sites could likely pose an adverse health risk to site staff and the surrounding sensitive groups. Therefore, it is necessary to carry out strict investigation and evaluation of the site, and timely repair and control to protect the water, soil, and air environment and to avoid the long-term cumulative exposure risk to human health caused by VOCs emission.

A High-Performing Nanostructured Ir Doped-TiO2 for Efficient Photocatalytic Degradation of Gaseous Toluene

TiO2-based photocatalysts still have some limitations such as large bandgap and low surface area, leading to low efficiency in the photocatalytic degradation of VOCs and limiting it to use in sunlight. Here we report that the nanostructured Ir-doped TiO2 as an efficient photocatalyst generates an excellent risk-reduction material of gaseous toluene. We have succeeded in developing a nanostructured Ir-doped TiO2 and initially found that excellent efficient photocatalytic VOC decomposition can be achieved in our materials The nanostructured Ir-doped TiO2 was synthesized by a one pot, low temperature hydrothermal process with different ratios of Ir doped into the TiO2. It exhibited a high surface area, uniformly spherical morphology of 10–15 nm. Its activity for the photocatalytic degradation of gaseous toluene exhibited up to 97.5% under UV light. This enhancement could be explained by iridium doping which created a high concentration oxygen vacancy and changed the recombination rate of the photogenerated charge carriers. More generally, our study indicates a strategic way to develop the novel nanostructured material for numerous applications.

Emission, dispersion, and potential risk of volatile organic and odorous compounds in the exhaust gas from two sludge thermal drying processes

Emissions of odorous and volatile organic compounds (VOCs) were investigated between two sludge drying methods. A total of 37 chemical compounds were identified and quantified from the off-gases from sludge drying by indirect drying method. The total number of VOCs detected ranged from 3.45 × 10^-3 to 4.53 mg/m³, which includes benzene series, volatile organic sulfur, and nitrogenous organic compounds. High emissions were found in the exhaust gas released from drying workshop that used direct drying method. Sulfur dioxide, aromatics, and chlorinated compounds were dominant. Based on the olfactory effect analysis and cancer risk assessment, the main odor-causing gaseous pollutants were methyl mercaptan and methyl sulfide (for indirect sludge drying process) and SO₂ (for direct sludge drying process), while the dominant carcinogens were benzene, carbon tetrachloride, chloroform, and methylene. This study provides new insights into the emission characteristics, olfactory effects, and cancer risks of VOCs and odorous compounds in the exhaust gas from thermal sludge drying processes.

Diffusion simulation, health risks, ozone and secondary organic aerosol formation potential of gaseous pollutants from rural comprehensive waste treatment plant

Comprehensive waste treatment plants (CWTPs) are significant sources of gaseous pollutants such as odors, volatile organic compounds (VOCs) and nitrogen oxides (NOx), polluting the environment and endangering human health. This study conducted on-site investigations on gaseous pollutants emissions from different areas of a CWTP. A total of 10 pollutants were identified of which ammonia (11.32 mg/m³ in average) was the main odorous substance, and benzene (19.51 mg/m³ in average) and toluene (42.07 mg/m³ in average) were the main VOCs. The feeding workshop (FW) was considered the main source of gaseous pollutants. The Gaussian plume model demonstrated that the pollution became more serious after spreading in the southeast downwind direction. Occupational exposure risks of on-site workers were mainly attributed to hydrogen sulfide, ammonia, benzene, and toluene, as their hazard index (HI) and lifetime cancer risk (CR) exceeded the recommended occupational safety limits. The gaseous pollutants diffused from CWTP may still pose a potential health risk to residents within a range of up to 7.5 km. The emulation and quantification of ozone formation potential by methods of Propyl-Equiv and MIR demonstrated that the contribution rate of toluene presented in each stage of CWTP exceed 80 %. Toluene was also the largest contributor to secondary organic aerosol with the contribution rate reached 56.34-85.14 %, followed by benzene (14.72-38.52 %). This research provides a basis for the reduction and control of gaseous pollutants in the treatment and disposal of rural domestic waste.

Contamination characteristics, source analysis and health risk assessment of heavy metals in the soil in Shi River Basin in China based on high density sampling

To explore the contamination of heavy metals in the Shi River Basin soil in China, a high density sampling of surface soil was conducted. In this study, an absolute principal component scores multiple linear regression model (APCS-MLR) was used to identify the sources of heavy metals in the soil and quantify their amounts. The methods to assess the heavy metals included a fuzzy synthetic evaluation, index and health risk assessment. The results show that heavy metals are relatively rich southwest of the study area. Their levels may be affected by natural sources, such as parent materials. The pollution caused by human factors cannot be ignored, and it is primarily influenced by traffic emissions and processing sources, which contribute 62.6%, followed by agricultural sources, such as pesticides and fertilizers, that contribute 21.1%. The risk assessment indicated that the study area was slightly to moderately polluted. All heavy metals pose higher carcinogenic and other health risks to children than adults, and ingestion is the main way that these pollutants enter the body. The carcinogenic risk of children owing to Cr from natural sources merits further study, while the carcinogenic risk to adults and the non-carcinogenic risk to both adults and children are at acceptable levels. Transportation and industrial processing sources are the main cause of the non-carcinogenic risk. The results could provide reference for reducing heavy metal pollution in the soil.

Attenuation mechanisms and key parameters to enhance treatment performance in vegetation filters: A review

In times when environmental concerns are on the rise and the search of ways to reduce waste generation and to create a circular economy is booming, Nature Based Solutions (NBSs) play a very important role. Vegetation Filters (VFs) are a type of Land Application System (LAS) in which wastewater is used to irrigate a forestry plantation to treat the water and produce biomass. VFs show multiple benefits that render this technology a suitable solution for wastewater treatment, especially for scattered populations or isolated buildings that lack of connection to sewer systems. This review aims to provide a comprehensive state of the art of VF implementation, highlighting the do's and don'ts for a successful performance focusing on those factors that are essential to water treatment. Results show that VFs have a great treatment capacity when all involving factors are considered, and their efficiency tends to increase with time, as the VF develops and "gets older". Indeed, the presence of fine-textured soils, the selection of a proper vegetation species, the use of pre-treated wastewater and a water balance-based irrigation schedule alternating wetting and -drying cycles are all factors that help to achieve the best performance. However, it is necessary to design and follow a simple but rigorous operation and maintenance schedule to avoid system failure, which could lead to NO₃-N leaching towards groundwater.

Trace volatile compounds in the air of domestic waste landfill site: Identification, olfactory effect and cancer risk

Landfill sites are regarded as sources of volatile compounds (VOCs) and odors emitted to the atmosphere. Surface emissions of VOCs and odors were investigated in a rural domestic waste landfill site located in southwest China. A total of 76 chemical compounds belonging to 3 chemical families were identified and quantified. The total number of VOCs (TVOC) detected ranged from 18.1 to 806.3 mg/m³, while odorous gases and greenhouse gases ranged from 0.4 to 21.2 and 0-100.5 mg/m³, respectively. High emissions were found in the air surrounding the leachate storage pool (LSP) and dumping area (DPA). The dominant species of VOCs were hexaldehyde, m-xylene, propylene oxide, acetophenone, and 2-butanone. The traceability analysis showed that the odors and VOCs diffused to the downwind boundary mainly came from the DPA and LSP. According to the olfactory effect analysis and cancer risk assessment, the main odor-causing gaseous pollutants were hydrogen sulfide, propionic acid, styrene, and 2-pentanone, while benzene, trichlorethylene, and 1,3-butadiene were the dominant carcinogens. This study provides new insights into the emission characteristics, olfactory effects, and cancer risks of VOCs and odors emitted from rural domestic solid waste landfill sites.

Environmental fate and aquatic effects of propylbenzenes and trimethylbenzenes: A review

Propylbenzenes (PBZs) and trimethylbenzenes (TMBs) are aromatic hydrocarbon compounds widely used in many industries with potential release to different environments. The fate and aquatic effects of these compounds in the environment were evaluated. Evidence suggests that PBZs and TMBs will rapidly volatilise from water and bioaccumulate in aquatic organisms. Under both aerobic and anaerobic conditions, these compounds are readily biodegradable, whereby 1,2,3-TMB is more stable than the others. In air, all five compounds have atmospheric photo-oxidation half-lives ranging from 0.31 to 1.55 d. The toxicity data collectively show that PBZs, 1,2,4- and 1,3,5-TMB pose high acute toxicity effects on aquatic organisms. Furthermore, freshwater species are more sensitive to these compounds than marine species. There is not much data on the occurrence of PZBs and TMBs in the aquatic environment. This review presents the current state of knowledge on the fate of PBZs and TMBs. Moreover, the acute and joint toxicity of these compounds to different aquatic organisms, especially in marine organisms, warrants further investigation.

Biological-based methods for the removal of volatile organic compounds (VOCs) and heavy metals

The current scenario of increased population and industrial advancement leads to the spoliation of freshwater and tapper of the quality of water. These results decrease in freshwater bodies near all of the areas. Besides, organic and inorganic compounds discharged from different sources into the available natural water bodies are the cause of pollution. The occurrence of heavy metals in water and volatile organic compounds (VOCs) in the air is responsible for a vast range of negative impacts on the atmosphere and human health. Nonetheless, high uses of heavy metals for human purposes may alter the biochemical and geochemical equilibrium. The major air contaminants which are released into the surroundings known as VOCs are produced through different kinds of sources, such as petrochemical and pharmaceutical industries. VOCs are known to cause various health hazards. VOCs are a pivotal group of chemicals that evaporate readily at room temperature. To get over this problem, biofiltration technology has been evolved for the treatment of heavy metals using biological entities such as plants, algae, fungi, and bacteria. Biofiltration technology is a beneficial and sustainable method for the elimination of toxic pollutants from the aquatic environment. Various types of biological technologies ranging from biotrickling filters to biofilters have been developed and they are cost-effective, simple to fabricate, and easy to perform. A significant advantage of this process is the pollutant that is transformed into biodegradable trashes which can decompose within an average time period, thus yielding no secondary pollutants. The aim of this article is to scrutinize the role of biofiltration in the removal of heavy metals in wastewater and VOCs and also to analyze the recent bioremediation technologies and methods.

Wastewater treatment, reuse, and disposal-associated effects on environment and health

This paper presents the review of the literature published in the year 2019 related to treatment and reuse of wastewater and effects on the environment and human health. The scientific review on the treatment and reuse of wastewaters is divided into various sections in the paper. The review sections cover wastewater management, reuse, removal of microorganisms, and chemical constituents. Besides, the review also covers research focused on wastewater treatment plants, disposal, and the management of wastewater sludge as well as biosolids in the environment. PRACTITIONER POINTS: This paper highlights the review of scientific literature published in the year 2019.Review provide issues related to health risks associated with human and the general environment on the reuse of wastewater, treatment as well as disposal.The literature review covers selected papers relevant to the topic.

The exposure risk of typical VOCs to the human beings via inhalation based on the respiratory deposition rates by proton transfer reaction-time of flight-mass spectrometer

The respiratory deposition rates are the important analytical parameters for human health risk assessment related to the environmental volatile organic compounds (VOCs). In present study, the deposition rates from the linear regressions of CH₂O, CH₅N, C₂H₆O, C₂H₄O₂, C₃H₈O, C₆H₆, C₇H₈, C₈H₈, and C₈H₁₀ of 120 healthy volunteers were obtained with significantly different from the respective calculated deposition rates. The CH₂O (formaldehyde) has the highest deposition rate, indicating the highest associated exposure risk of CH₂O if the persons are exposed to the same concentrations of these VOCs through inhalation. In order to explore the effects of the breathing models and sampling time on the deposition rates of VOCs, volunteers were first asked to breathe successively with nasal-in-nasal-out, oral-in-nasal-out, and oral-in-oral-out breathing models before and after three meals for three days. Sampling time variation has no effect on the deposition rates of selected VOCs, while the deposition rates of C₂H₄O₂, C₃H₈O, C₆H₆, C₇H₈ and C₈H₁₀ by nasal-in-nasal-out were significantly different from oral-in-oral-out and nasal-in-oral-out models. Among all the breathing models, nasal-in-oral-out comprises the entire respiratory system. In order to further validate the results, the deposition rates of the selected VOCs were calculated in 120 healthy volunteers using nasal-in-oral-out breathing model for unlimited time after the conventional lung function examination. Difference in gender and body mass index had no effect on the deposition rates of VOCs, while the age affects the deposition rates of CH₂O, CH₅N and C₂H₄O₂. Positive correlation analysis between lung function factors and deposition rates revealed that the individuals with larger lung function factors are more susceptible to deposit the VOCs. Overall, the main conclusion can be drawn that the respiratory deposition rates were influenced by the physiological factors. Therefore, the major objective for future research is to accurately calculate the deposition rates of environmental VOCs for health-risk assessment.

Ready-to-use, functionalized paper test strip used with a smartphone for the simultaneous on-site detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater

The simultaneous detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater samples was performed. In this report, we designed and fabricated functionalized paper test strips featuring detection zones that use 3-aminopropyltriethoxysilane (APTES) for the immobilization of chromogenic substrates to detect free chlorine, hydrogen sulfide and formaldehyde. After multiple chromogenic reactions, red, blue and purple colors were obtained on the detection zones and analyzed using a smartphone. Under optimum conditions, the paper test strips showed 1.7, 1.8 and 1.7 orders of magnitude for free chlorine, hydrogen sulfide and formaldehyde, respectively. This sensitivity is caused by the formation of homogeneous complexes on detection zones resulting from the chromogenic reagents immobilized on the detection zone via APTES. Through this strategy, free chlorine, hydrogen sulfide and formaldehyde analysis was achieved within 5 min with detection limits of 0.08, 0.14 and 0.13 mg L^-1, respectively. The developed paper test strip was able to selective detection of free chlorine, hydrogen sulfide and formaldehyde even in the presence of common interfering agents therefore, the test strip was highly selective. In a further demonstration, the developed functionalized paper test strip was successfully used for simultaneous detection of free chlorine, hydrogen sulfide and formaldehyde in wastewater in the field and exhibited with high precision and accuracy in detecting free chlorine, hydrogen sulfide and formaldehyde in wastewater samples. Compared to other methods, this assay was advantageous in terms of its low detection limit, time savings, good stability and highly portable format, which facilitates rapid on-site environmental monitoring with a smartphone.

Effects of substrate fluctuation on the performance, microbial community and metabolic function of a biofilter for gaseous dichloromethane treatment

Dichloromethane (DCM) is a harmful volatile organic compound that usually originates from pharmaceutical industry. In this study, the treatment of gaseous DCM in a biofilter was investigated by gradually increasing the DCM inlet concentration. Nearly 80% of DCM could be removed when the inlet concentration was lower than 0.30 g m^-3. The maximum elimination capacity of 26.6 g m^-3·h^-1 was achieved at an inlet loading rate of 38.4 g m^-3·h^-1. However, with the increase in the inlet concentration to more than 0.60 g m^-3, the removal efficiency obviously decreased to about 40%. After a starvation period of 2 weeks, the biofilter rapidly recovered its performance. The Haldane model including a substrate inhibition term was applied to describe the kinetics of the biofilter. High-throughput sequencing indicated that DCM-degrading genera, such as Rhodanobacter sp., Hyphomicrobium sp., Rhizomicrobium sp., Bacillus sp., Pseudomonas sp., and Clostridium sp., were dominant in the biofilter in different operation phases. The microbial communities and diversities were greatly affected by the DCM concentration. Microbial metabolic functions were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The results indicated that xenobiotics biodegradation and metabolism, carbohydrate metabolism, and amino acid metabolism were the three most abundant metabolic pathways of the microbes. The abundances of these metabolic functions were also altered by the DCM concentration.