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

Research on pollution identification and safety thresholds based on the olfactory effect on a halogenated hydrocarbon contaminated site

To effectively address odor control issues at sites contaminated with halogenated hydrocarbons, it is essential to establish an odor risk prediction system for evaluating potential risks that may impact future planning. This research focuses on a representative halogenated hydrocarbon-contaminated site, examining the spatial and temporal distribution characteristics of key pollutants in soil gas. By analyzing odor contribution rates, the study identifies significant odorants in soil gas, which enables the derivation of both probabilistic and deterministic safety thresholds for soil and groundwater based on olfactory effects. The findings indicate that 1,1-dichloroethylene, vinyl chloride, chloroform, and 1,1-dichloroethane are prevalent throughout the contaminated site, displaying elevated concentration levels and substantially influencing the overall contamination extent. These substances are highlighted as critical pollutants requiring attention. Correlation analysis (P < 0.05) reveals a strong relationship between the concentrations of vinyl chloride, 1,1-dichloroethane, and chloroform with groundwater depth and air temperature. Additionally, the analysis of odor activity values (OAV) identified 1,1-dichloroethene, 1,4-dichlorobenzene, chlorobenzene, chloroform, and vinyl chloride as key olfactory factors at the site. The corresponding probabilistic safety thresholds are 0.68, 1.65, 0.50, 7.87, and 3.72 mg kg-1 for soil, and 9.29, 3.46, and 1.09, 69.55, and 47.01 mg L-1 for groundwater, respectively. Among them, the odor risks of chlorobenzene and 1,1-dichloroethylene warrant more attention than soil contamination risks; regarding 1,4-dichlorobenzene, it is recommended to concurrently consider odor risks during human health risk assessment; as for vinyl chloride and chloroform, their odor risks can be largely eliminated based on human health-oriented pollution management.

Assessing the spatial distribution of odor at an urban waterfront using AERMOD coupled with sensor measurements

Impressions of a place are partly formed by smell. The urban waterfronts often leave a rather poor impression due to odor pollution, resulting in recurring complaints. The nature of such complaints can be subjective and vague, so there is a growing interest in quantitative measurements of emissions to explore the causes of malodorous influence. In the present work, an air quality monitor with an H2S sensor was employed to continuously measure emissions of malodors at 1-min resolution. H2S is often considered to be the predominant odorous substance from sludge and water bodies as it is readily perceptible. The integrated means of concentration from in situ measurements were combined with the AERMOD dispersion model to reveal the spatial distribution of odor concentrations and estimate the extent of odor-prone areas at a daily time step. Year-long observations showed that the diurnal profile exhibits a positively skewed distribution. Meteorology plays a vital role in odor dispersion; the degree of dispersion was explored on a case-by-case basis. There is a greater likelihood of capturing the concentration peaks at night (21:00 to 6:00) as the air is more stable then with less tendency for vertical mixing but favors a horizontal spread. This study indicates that malodors are changeable in time and space and establishes a new approach to using H2S sensor data and resolves a long-standing question about odor in Hong Kong.Implications: this study establishes a new approach combining dispersion model with novel H2S sensor data to understand the characteristics and pattern of odor emanated from the urban waterfront in Hong Kong. The sensor has dynamic concentration range to detect the episodic level of H2S and low level at background conditions. It provides more complete information in relation to odor annoyance, as well as quantitative information useful for odor regulation.

Release characteristics of volatile organic compounds at residential garbage collection points: a case study of Hangzhou, China

With the implementation of garbage classification, perishable waste has become increasingly concentrated. This has led to a significant change in the VOC release characteristics at residential garbage collection points, posing a potential risk with unknown characteristics. This study investigated the release characteristics, odor pollution, and health risks of VOCs at garbage collection points under different classification effectiveness, seasons, garbage drop-off periods, and garbage collection point types. The results showed that the average concentration of VOCs released from the garbage sorting collection points (SPs) was 341.43 ± 261.16 μg/m3, and oxygenated compounds (e.g., ethyl acetate and acetone) were the main VOC components. The VOC concentration increased as the community classification effectiveness improved, and it was higher in summer (followed by spring, autumn, and winter). Moreover, the VOC concentrations were higher in the evenings than in the mornings and at centralized garbage collection points (CPs) than at SPs. Further, odor activity value (OAV) assessments indicated that acrolein, styrene, and ethyl acetate were the critical odorous components, with an average OAV of 0.87 ± 0.85, implying marginal odor pollution in some communities. Health risk assessments further revealed that trichloroethylene, benzene, and chlorotoluene were the critical health risk substances, with an average carcinogenic risk (CR) value of 10-6-10-4, and a non-carcinogenic risk (HI) value < 1. These results indicated that HIs were acceptable, but potential CRs existed in the communities. Therefore, VOC pollution prevention and control measures should be urgently strengthened at the garbage collection points in high pollution risk scenarios.

Association of serum individual and mixed aldehydes with depressive symptoms in the general population: A machine learning study

BACKGROUND

Humans have many opportunities to be exposed to aldehydes which have potential mechanisms for causing depression. We aimed to explore the relationships between serum individual and mixed aldehydes with depressive symptoms in general population.

METHODS

The data was extracted from the National Health and Nutrition Examination Survey 2013-2014. Depressive symptoms were assessed by Patient Health Questionnaire-9. Weighted binomial logistic regression and Bayesian kernel machine regression (BKMR) model were used to explore the association of six individual aldehyde and mixed aldehydes with depressive symptoms, respectively. Sex stratification analysis and sensitivity analysis were conducted.

RESULTS

A total of 701 participants were included. We found a positive association between the highest (Q4) versus lowest quartile (Q1) of butyraldehyde with depressive symptoms (OR: 2.86, 95 % CI: 1.22-6.68), and a negative association between the Q3 versus Q1 of benzaldehyde (0.21, 0.07-0.60) and isopentanaldehyde (0.28, 0.08-0.90) with depressive symptoms in multivariate-adjusted model. The mixed aldehydes were positively associated with depressive symptoms using BKMR model, and butyraldehyde and heptanaldehyde were the dominant aldehydes. Several aldehydes, such as butyraldehyde and benzaldehyde, interacted with each other in their effects on depressive symptoms. The results of gender stratification analysis showed that butyraldehyde was the major contributor to the total effect of aldehydes on depressive symptoms in males, while heptanaldehyde was the dominant aldehyde in females.

LIMITATIONS

Causality cannot be inferred in this cross-sectional study.

CONCLUSIONS

Our study indicated that mixed aldehydes can increase the risk of depressive symptoms, of which butyraldehyde and heptanaldehyde were the major contributing aldehydes.

Characterizing emissions of VOCs from the initial degradation of kitchen waste in household waste bins of residential areas in Beijing

In order to clarify the emission characteristics of VOCs during the initial degradation of kitchen waste, a year-long sampling campaign of kitchen waste in residential household municipal solid waste (HMSW) bins was conducted. A total of 93 VOCs with an average annual concentration of 2271 μg/m3 were detected. Alkanes and oxygenated compounds were the dominant released from the initial degradation of kitchen waste. Seasonal and daily variations were observed, with VOC concentrations generally higher in spring (1413 μg/m3) and summer (5882 μg/m3) and lower in autumn (505 μg/m3) and winter (1258 μg/m3). In addition, peak releases occurred earlier in the spring and summer (at 6 h) than in autumn and winter (at 24 h). Correlation analysis showed that ambient temperature correlated significantly with alkanes and oxygenated compounds (P < 0.01). 67 substances have been found to cause odor pollution. Based on the odor index, oxygenated compounds were the most significant odor pollutants. Acetaldehyde and 2-ketone required particular concern because of its high concentration and high odor index. This study not only enriched the understanding of emissions of VOCs from MSW front-end facilities but will also provide a scientific and theoretical basis for holistic management and odor control of MSW.

Contaminant characterization of odor in soil of typical pesticide-contaminated site with shallow groundwater

Odor emission from the soil of pesticide-contaminated sites is a prominent environmental problem in China, but there are very few researches about the component and spatial distribution of odorous substances in the soil of contaminated sites. In this paper, to investigate the odor pollution condition of an organophosphorus pesticide production site in a city of South China, the odor pollutants in the soil and soil gas were analyzed and the key odor-contributing substances were identified. Besides, the correlation between the concentrations of odorous substances in soil and soil gas was analyzed, and the measured results were compared with the predicted results by the linear model and DED model. An off-line soil gas sampling device was designed to collect the gas emitted from soil because the groundwater level in the site was too shallow to build a soil gas well. The key odor substances were screened from the detection results of soil gas via odor activity value (OAV) analysis, which revealed that the key odorous substances included benzene, ethylbenzene, ammonia, toluene, m,p-xylene, methyl sulfide, dimethyl disulfide, and formaldehyde. Furthermore, the spatial distribution of the odor substances in the soil of the pesticide-contaminated site was closely related to the layout and geologic structure of the site. The odor pollutants in soil were mainly distributed near the phosmet production workshop and the drainage ditch network. As for the deep distribution, the odorous substances were mainly enriched in the silty clay or clay layer (5.6-11 m), followed by the sludge layer (1-3.6 m). Finally, the predicted model (linear model and DED model) analysis suggested that the linear model was more suitable for predicting the concentration of odorous substances in the soil gas with the detection data of soil in this pesticide-contaminated site.

Combined assessment of health hazard and odour impact of soils at a contaminated site: a case study on a defunct pharmaceuticals factory in China

Surveys and assessments of contaminated sites primarily focus on hazardous pollutants in the soil with less attention paid to odorants. This makes the management of contaminated sites difficult. In this study, hazardous and odorous pollutants in the soil were assessed for a large site that was previously used for production of pharmaceuticals to determine the degree and characteristics of soil contamination at pharmaceutical production sites, for undertaking rational remediation measures. The main hazardous pollutants at the study site were triethylamine, n-butyric acid, benzo(a)pyrene (BaP), N-nitrosodimethylamine (NDMA), dibenzo(a,h)anthracene (DBA), total petroleum hydrocarbons (C10-C40) (TPH), and 1,2-dichloroethane; TEA, BA, and isovaleric acid (IC) were the main odorants. As the type and distribution of hazardous and odorous pollutants differ, it is necessary to separately assess the impact of these pollutants at a contaminated site. Soils in the surface layer pose significant non-carcinogenic (HI = 68.30) and carcinogenic risks (RT = 3.56E-5), whereas those in the lower layer only pose non-carcinogenic risks (HI > 7.43). Odorants were found at considerable concentrations both in the surface and lower layers, with the maximum concentrations being 29,309.91 and 41.27, respectively. The findings of this study should improve our understanding of soil contamination at former pharmaceutical production sites and should inform the assessment of the risks posed by contaminated sites, with problems associated with odour, and possible remediation strategies.

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.

Treatment of compressed leachate from refuse transfer stations by freeze-melt method

A small amount of leachate with complex composition will be produced during the compressing of municipal solid waste in refuse transfer stations. In this study, the freeze-melt method, a green and efficient wastewater treatment technology, was used to treat the compressed leachate. The effects of freezing temperature, freezing duration, and ice melting method on the removal rates of contaminants were investigated. The results showed that the freeze-melt method was not selective for the removal of chemical oxygen demand (COD), total organic carbon (TOC), ammonia-nitrogen (NH₃-N) and total phosphorus (TP). The removal rate of contaminants was positively correlated with freezing temperature and negatively correlated with freezing duration, and the slower the growth rate of ice, the higher the purity of ice. When the compressed leachate was frozen at -15 °C for 42 h, the removal rates of COD, TOC, NH₃-N and TP were 60.00%, 58.40%, 56.89% and 55.34%, respectively. Contaminants trapped in ice were removed during the melting process, especially in the early stages of melting. The divided melting method was more beneficial than the natural melting method in removing contaminants during the initial stage of melting, which contributes to the reduction of produced water losses. This study provides a new idea for the treatment of small amounts of highly concentrated leachate generated by compression facilities distributed in various corners of the city.

Characteristics of leachate from refuse transfer stations in rural China

The properties of leachate from refuse transfer stations (RTSs) in rural China were indefinite. In this study, a total of 14 leachate samples from RTSs in nine provinces of China were characterized for their pH, electric conductivity, chromaticity, concentration of organic substances, nitrogen distribution, volatile organic compounds (VOCs), organic phosphorous pesticide, and heavy metals. The structural composition of fluorescent dissolved organic matter (FDOM) was also determined. To evaluate the leachate pollution potential in this study, a leachate pollution index was derived and used. Chromium (Cr) was the most polluting heavy metal present in rural leachate. Ethanol and ethyl acetate were the most frequently detected VOCs at high concentrations. Three-dimensional fluorescence excitation-emission matrix spectra were used to characterize the FDOM. Three components, tryptophan (C₁), tyrosine-like (C₂), and humic acid- and fulvic acid-like (C₃) substances, were identified from all 14 samples. Tryptophan was the major component of FDOM and present in 45.7% of the samples by calculating the fluorescence intensity percentage, on average. Pearson correlations revealed that the fluorescence intensity of C₁ and C₃ was strongly related to soluble chemical oxygen demand and dissolved oxygen carbon, while C₂ had significant positive correlations with ammonia nitrogen and total phosphorus of the solid waste. This study provided detailed data and findings that could serve as a preliminary basis for broadening options for the treatment and management of leachate from rural RTSs in China.

Volatile organic compound emissions in free-range chicken production: Impacts on environment, welfare and sustainability

<abstract> <p>The increasing demand for free-range poultry products has led to a surge in their availability in the market, prompting a potential decline in premium prices associated with these products. This shift places considerable pressure on upstream costs in chicken production. A comprehensive under-standing of its impact on the environment is essential to ensure the success of commercial and industrial free-range chicken production. However, there exists a significant knowledge gap concerning the emission and concentrations of volatile organic compounds (VOCs) from organic-free range chicken, and their environmental implications have yet to be understood. We aim to address this critical knowledge gap by elucidating the role of VOC emissions in chicken production and assessing their impact on human and animal health, as well as environmental challenges. Understanding the implications of VOC emissions is essential for promoting sustainable and responsible free-range chicken farming practices. By identifying the sources of VOC emissions and their impacts, stakeholders can implement appropriate measures to optimize air quality and enhance the well-being of chickens and workers. Ultimately, this review highlights the role of VOCs in animal production, providing valuable insights for improving the efficiency, environmental sustainability and welfare aspects of free-range chicken farming.</p> </abstract>

Association between aldehyde exposure and kidney stones in adults

Environmental pollution sources may play a key role in the pathogenesis of nephrolithiasis, although the link between environmental aldehyde exposure and the incidence of nephrolithiasis is unclear. The researchers in this study set out to see whether adult kidney stone formation was linked to environmental aldehydes. We examined data from 10,175 adult participants over the age of 20 who took part in the 2013-2014 National Health and Nutrition Examination Survey (NHANES), which was a cross-sectional research. A logistic regression model was employed in this work to examine the relationship between aldehyde exposure and kidney stones, machine learning was utilized to predict the connection of different parameters with the development of kidney stones, and a subgroup analysis was performed to identify sensitive groups. After controlling for all confounding variables, the results revealed that isopentanaldehyde, benzaldehyde, and hexanaldehyde were risk factors for kidney stone formation, with odds ratio (OR) of 2.47, 1.12, and 1.17, respectively, and 95 percent confidence intervals (95% CI) of 1.15-5.34, 1.02-1.22, and 1.00-1.36. Kidney stones may be a result of long-term exposure to aldehydes, which may cause them to form. Environmental pollution-related aldehyde exposure might give a novel notion and direction for future study into the process of kidney stone production, even if the cause is yet unknown.

A sustainable Decision Support System for soil bioremediation of toluene incorporating UN sustainable development goals

Decision Support System (DSS) is a novel approach for smart, sustainable controlling of environmental phenomena and purification processes. Toluene is one of the most widely used petroleum products, which adversely impacts on human health. In this study, Fusarium Solani fungi are utilized as the engine of the toluene bioremediation procedure for the monitoring part of DSS. Experiments are optimized by Central Composite Design (CCD) - Response Surface Methodology (RSM), and the behavior of the mentioned fungi is estimated by M5 Pruned model tree (M5P), Gaussian Processes (GP), and Sequential Minimal Optimization (SMOreg) algorithms as the prediction section of DSS. Finally, the control stage of DSS is provided by integrated Petri Net modeling and Failure Modes and Effects Analysis (FMEA). The findings showed that Aeration Intensity (AI) and Fungi load/Biological Waste (F/BW) are the most influential mechanical and biological factors, with P-value of 0.0001 and 0.0003, respectively. Likewise, the optimal values of main mechanical parameters include AI, and the space between pipes (S) are equal to 13.76 m³/h and 15.99 cm, respectively. Also, the optimum conditions of biological features containing F/BW and pH are 0.001 mg/g and 7.56. In accordance with the kinetic study, bioremediation of toluene by Fusarium Solani is done based on a first-order reaction with a 0.034 s-1 kinetic coefficient. Finally, the machine learning practices showed that the GP (R2 = 0.98) and M5P (R2 = 0.94) have the most precision for predicting Removal Percentage (RP) for mechanical and biological factors, respectively. At the end of the present research, it is found that by controlling seven possible risk factors in bioremediation operation through the FMEA- Petri Net technique, efficiency of the process can be adjusted to optimum value.