Odor emissions: A public health concern for health risk perception

Research on cluster hollow fiber membrane proton transfer reaction mass spectrometry (CHFM-PTR-MS) and its application in odorous gas detection

Odorous gas emission is one of the world's seven major public nuisances, easily causing disturbances and complaints, and posing a threat to air quality and public health. Emissions of odorous substances are characterized by their sudden and instantaneous nature, with some odorous compounds having extremely low olfactory thresholds. Therefore, it is essential to develop highly sensitive on-site rapid detection techniques. This paper presents a new technology that combines a cluster hollow fiber membrane (CHFM) with mobile proton transfer reaction mass spectrometry (PTR-MS), developing a cluster hollow fiber membrane-proton transfer reaction mass spectrometry (CHFM-PTR-MS) technique. Due to the large membrane area (1000 cm2) of the cluster hollow fiber membrane module, the CHFM-PTR-MS shows improved sensitivity for eight tested odorous substances by 7.6 to 12.2 times and an enhanced limit of detection by 6.7 to 12.4 times compared to traditional direct-injection PTR-MS. Through a 28-hour continuous monitoring experiment of odorous gases released from household waste, the capability of the new CHFM-PTR-MS technology for on-site rapid detection of trace odorous organic compounds was verified. The CHFM-PTR-MS is expected to provide a new technique and device for on-site rapid detection of odorous organic compounds with high sensitivity.

Catalytic Oxidative Removal of Volatile Organic Compounds (VOCs) by Perovskite Catalysts: A Review

Volatile organic compound (VOC) emissions have become a critical environmental concern due to their contributions to photochemical smog formation, secondary organic aerosol generation, and adverse human health impacts in the context of accelerated industrialization and urbanization. Catalytic oxidation over perovskite-type catalysts is an attractive technological approach for efficient VOC abatement. This review systematically evaluates the advancements in perovskite-based catalysts for VOC oxidation, focusing on their crystal structure-activity relationships, electronic properties, synthetic methodologies, and nanostructure engineering. Emphasis is placed on metal ion doping strategies and supported catalyst configurations, which have been demonstrated to optimize catalytic performance through synergistic effects. The applications of perovskite catalysts in diverse oxidation systems, including photocatalysis, thermal catalysis, electrocatalysis, and plasma-assisted catalysis, are comprehensively discussed with critical analysis of their respective advantages and limitations. It summarizes the existing challenges, such as catalyst deactivation caused by carbon deposition, sulfur/chlorine poisoning, and thermal sintering, as well as issues like low energy utilization efficiency and the generation of secondary pollutants. By consolidating current knowledge and highlighting future research directions, this review provides a solid foundation for the rational design of next-generation perovskite catalysts for sustainable VOC management.

Functional coatings for textiles: advancements in flame resistance, antimicrobial defense, and self-cleaning performance

The continuous evolution of textile technologies has led to innovative functional coatings that enhance protective textiles by integrating flame retardancy, antimicrobial efficacy, and self-cleaning properties. These multifunctional coatings address the growing demand for high-performance materials in healthcare, military, and industrial applications. This study reviews advancements in coating techniques, including dip-coating, spray-coating, sol-gel processes, and layer-by-layer assembly, highlighting their effectiveness in imparting durability, thermal stability, and biological activity to textile substrates. The incorporation of bioactive materials such as chitosan, silver nanoparticles, and plant-derived antimicrobials has demonstrated enhanced pathogen resistance and prolonged fabric functionality. Furthermore, recent developments in phosphorus-based flame retardants and photocatalytic self-cleaning agents, including titanium dioxide and silica nanoparticles, have contributed to the sustainability of functional textiles by reducing environmental impact. Challenges remain in achieving compatibility among diverse functional components while maintaining mechanical integrity and user comfort. Scalability and cost-efficiency also present barriers to commercialization, necessitating cross-disciplinary collaboration among material scientists, engineers, and regulatory experts. Future research should focus on biodegradable alternatives, smart-responsive coatings, and advanced nanomaterial integration to enhance the longevity and eco-friendliness of protective textiles. As industry standards shift towards sustainability, functional coatings are poised to redefine textile applications, offering tailored solutions that balance safety, performance, and environmental responsibility. This review underscores the transformative potential of multifunctional textile coatings and their role in advancing next-generation protective fabrics.

A comparative study of wind tunnel and flux chamber for diffuse emission sampling: Experimental evaluation and theoretical approach

One of the most complex challenges in the field of industrial odour emissions is the characterization of passive area sources, which emit contaminants even if not endowed with their own gas flow. Two primary sampling devices have been developed for this scope: Wind Tunnel (WT), with a unidirectional airflow without vertical mixing, and Flux Chamber (FC), with a turbulent well-mixed flow. Essentially, two are the debated issues about the sampling instrumentation. The first concerns which device is more suitable for accurately describing the real fluid dynamic behaviour at the liquid-gas interface. The second issue involves the extent to which the emission rates, estimated by the two sampling systems, differ. This study addresses these debates providing experimental data on the real atmospheric motion near liquid surfaces, aiding the choice between WT and FC. Field tests reveal that atmospheric conditions can make the fluid dynamics similar to either WT or FC, with the general scenario showing an intermediate wind behavior. Thus, it is not possible to a priori determine the most suitable device. Concerning the second issue, this research presents an experimental comparison of VOCs (Volatile Organic Compounds) emission rates between a recently developed WT and a US-EPA design FC. These trials indicate that for soluble compounds, WT and FC yield comparable results. However, for gas-phase controlled species (low-solubility VOCs), WT tends to overestimate emissions compared to FC, with the ratio of specific emission rates ranging from 2 to 4.5. The developed theoretical mass transfer model aligns well with observed values, except for toluene due to its non-ideal mixture with water.

Screening characteristic VOC species, health hazards, and odor pollutants in the grain and oilseed milling industry of China

Grain and oilseed milling industries are significant sources of VOCs, leading to substantial human health risks and odor pollution. However, the VOC emission remain inadequately characterized, hindering the development of effective pollution mitigation strategies. VOC samples were collected discharged from the rapeseed oil, sesame oil, soybean oil, and wheat flour manufacturing workshops in the Pearl River Delta, China. The VOC concentrations and emission profiles were evaluated, and VOC concentrations in a nearby residential area were simulated using the CALPUFF dispersion model for health risk and odor assessments. The results revealed substantial variations in both VOC concentrations (0.4-8.3 mg m-3) and compositions among the different workshops. N-hexane was the predominant species in the extraction and refining processes at rapeseed oil (91.17%) and soybean oil factories (86.25%). Carbon disulfide (50.24%) and dimethyl sulfide (51.48%) were also important in the rapeseed oil workshop, while propanone (24.66-45.35%) was the major species in the sesame oil factory. In the wheat flour factory, the main VOCs were ethyl acetate (40.04%) and trichloromethane (29.39%). Non-cancer and cancer risks, as indicated by hazard index (HI, 9.74 × 10-6∼4.75 × 10-3) and cancer index (CI, 2.12 × 10-9∼2.78 × 10-7), both of which are much lower than the acceptable limits (HI = 1 and CI = 10-6), suggesting that the factories do not pose a significant health risk to nearby residents. The highest non-cancer risk was found in the extraction workshop of rapeseed oil, while the highest cancer risk was associated with trichloromethane from the fermentation workshop of wheat flour. The rapeseed oil industry posed the highest risk of odor pollution to nearby neighborhoods, with species such as CS2, dimethyl sulfide, and acrolein contributing most to the odor pollution, resulting in odor indices (OI) ranging from 2 to 31. These findings suggest that the high variability in VOC concentrations and compositions among the workshops is primarily due to production technologies and raw materials.

Advancing frontiers in skin offensive odor management: from innovative diagnostics to cutting-edge treatments and emerging technologies

Skin bromhidrosis, commonly referred to as body odor, is caused by the microbial breakdown of sweat, leading to the formation of volatile organic compounds (VOCs) that result in unpleasant odors. While body odor is a natural consequence of sweat production, excessive or persistent odor can significantly affect quality of life, causing social stigma and psychological distress. Traditional approaches to managing body odor, such as antiperspirants and deodorants, have limitations, necessitating the development of more advanced diagnostic tools and treatments. This review aims to explore recent advancements in the diagnosis and treatment of skin offensive odor, focusing on cutting-edge technologies and novel approaches. It highlights the interplay of the skin microbiome, sweat gland activity, and external factors in odor formation and investigates innovative solutions for long-term odor management. Emerging diagnostic techniques, such as electronic nose (E-nose) technology, gas chromatography-mass spectrometry (GC-MS), and next-generation sequencing (NGS), enable precise detection and analysis of odor-causing VOCs and microbial profiles. These tools facilitate a deeper understanding of the pathophysiology of odor production. Treatment innovations include nanotechnology-based antimicrobials (e.g., silver and zinc oxide nanoparticles), probiotic formulations for microbiome modulation, and odor-neutralizing compounds such as cyclodextrins and enzymatic neutralizers. Advanced delivery systems, including microneedle patches and nanoencapsulation, enable targeted, sustained release of active ingredients. Additionally, systemic approaches like oral probiotics and dietary interventions offer complementary strategies for managing body odor. The integration of novel diagnostics with innovative topical and systemic treatments offers promising avenues for more effective and personalized management of skin offensive odor. These advancements pave the way for improved quality of life for individuals affected by bromhidrosis, with potential for widespread application in personal care and medical contexts. Clinical trial number: Not applicable.

Effect of variation in temperature on malodor generation from different units of a wastewater treatment plant

This study investigates the effect of temperature variation on malodor generation across different units of a wastewater treatment plant (WWTP). The results demonstrate that higher temperatures exacerbated odor emission due to increased microbial activity with all the different units showing maximum odorous gas production at the highest temperatures used (35 °C and 45 °C) in this study. The maximum total odor activity value (OAV) of 353106 was obtained for anoxic and anaerobic unit at 45 °C. The variation in composition of odor-causing gases was also dependent on wastewater characteristics than temperature alone. Volatile reduced sulfur compounds, including hydrogen sulfide and methyl mercaptan, were dominant in most wastewater samples, while units with higher dissolved oxygen (DO) content, such as aeration and sedimentation units, exhibited elevated levels of phenol and dimethyl disulfide and reduced H2S concentration. Analysis of the liquid composition following incubations revealed presence of mainly aldehydes (> 75%) which are produced due to incomplete organic matter degradation, particularly at lower temperatures. Statistical analysis showed positive correlation between temperature and odor generation. DO had negative correlation with H2S (r =  - 0.78, - 0.93) along with total gas concentration and total OAV, but positively correlated with other gases, namely methyl mercaptan (r = 0.22, 0.97), dimethyl disulfide (r = 0.93, 0.98), phenol (r = 0.99, 0.97), and ammonia (r = 0.99, 0.98). Solids concentration and volatile solids to total solids (VS/TS) ratio had positive correlation with H2S, total gas concentration, and total OAV (r = 0.68, 0.54, and 0.90). These findings highlight the need for tailored odor management strategies based on temperature fluctuations and unit-specific conditions to optimize WWTP operations and reduce odor emissions effectively.

Distance and Direction Matters: Risk Perception Among Residents Around a Dump Yard in Kerala, India

Purpose

Waste mismanagement is a growing concern in developing countries where unsustainable practices such as open dumping and open burning are rampant. This study examined the risk perceptions of the residents living in proximity to the Brahmapuram dump yard, situated in Ernakulam district of Kerala State, India- A site marked by persistent local protests, public outrage, and legal disputes arising from issues related to waste mismanagement. The study focused on the geospatial and sociodemographic factors that might influence these perceptions.

Patients and Methods

A cross-sectional survey was conducted among 302 respondents living within 4 kilometers from the borders of the dump yard using a structured interview schedule. The responses of the participants were used to compute a risk perception score, which reflected participants' risk perception regarding the environment and their health.

Results

Among the participants in the study, those who lived within 2 kilometers (2.3 (95% CI 0.96, 3.7; p<0.001)), those who lived to the east (2.7 (95% CI 1.1, 4.2; p<0.001)) and those who reported perceiving strong malodor from the dump yard (2.0 (95% CI 0.54, 3.4; p=0.007)), had a higher risk perception in the multivariate linear regression model. Women had a lesser risk perception compared to men (-2.6 (95% CI -3.7, -1.4; p<0.001)).

Conclusion

The findings highlight the importance of geospatial characteristics (distance and direction), malodor and gender differences in shaping the risk perceptions among the proximate residents living around a waste dump yard. Consideration of geospatial and sociodemographic determinants in risk assessment and management could potentially reduce the perceived risks and public discontent around waste management facilities.

An overview on olfaction in the biological, analytical, computational, and machine learning fields

Recently, the comprehension of odor perception has advanced, unveiling the mysteries of the molecular receptors within the nasal passages and the intricate mechanisms governing signal transmission between these receptors, the olfactory bulb, and the brain. This review provides a comprehensive panorama of odors, encompassing various topics ranging from the structural and molecular underpinnings of odorous substances to the physiological intricacies of olfactory perception. It extends to elucidate the analytical methods used for their identification and explores the frontiers of computational methodologies.

Bioaerosols and VOC emissions from landfill leachate treatment processes: Regional differences and health risks

The landfill leachate treatment process (LLTP) is a crucial anthropogenic source of bioaerosols and volatile organic compounds (VOCs) with potential environmental impacts and on-site health risks to plant workers. However, factors influencing microbial aerosol and VOC emissions remain poorly understood. We sampled and analyzed bioaerosols and VOCs in two process sections (oxidation ditch [OD] and reverse osmosis membrane [RO]) of LLTPs in northern (NLF) and southern (SLF) China. Bioaerosol concentrations were highest in OD, and particle size predominantly ranged from 0.654.7 µm. Microbial community analysis revealed distinct differences between geographical locations and process sections, with 332 genera identified. Genera such as Paenibacillus, Bacillus, and Pseudomonas were prevalent at all sampling sites. Oxygen-containing compounds (e.g., acetophenone and propionic acid) were the dominant VOCs, particularly in SLF-OD. Network analysis showed complex interactions, with Sphingomonas and ketones playing central roles in microbial and VOC communities, respectively. Partial least squares (PLS) modeling indicated a significant correlation between bioaerosols and VOCs. Specific microorganisms, such as TK10, Adhaeribacter, and Lachnospiraceae, were major contributors to emissions of hazardous VOCs (e.g., toluene and styrene). The ozone-generation potential and olfactory effect of the OD were significantly higher than those of RO; and those of SLF were higher than those of NLF. Health risk assessments indicated potential chronic toxicity and cancer risks associated with VOC exposure to specific compounds, such as trichloroethylene. Bioaerosol exposure occurred primarily through inhalation, particularly in male workers. This study establishes a theoretical foundation for the prevention and control of air-phase pollutant risks associated with LLTPs.

Environmental health risk assessment and acute effects of sulfur dioxide (SO2) inhalation exposure on traditional sulfur miners at Ijen Crater Volcano, Indonesia

The Ijen Crater volcano is one of the geological wonders recognized by UNESCO. Inside it is a blue lake with a high acidity level, and a blue fire phenomenon has formed due to the very high concentration of sulfur. This crater is also one of Indonesia's largest sources of sulfur and is used by locals as a traditional sulfur mine. This study aims to measure SO2 concentrations and assess the health risks of SO2 exposure in traditional sulfur mine workers. The SO2 measurements were taken using impingers at six sample points along the mine workers' path. In addition, anthropometric data, work activity patterns, and health complaints during work were collected through direct interviews with 30 respondents selected based on inclusion criteria. Short-Term Health Impact Method was carried out based on a comparison of threshold level values and acute effects obtained from interviews regarding health complaints. The Hazard Question Index (HQ Index) of SO2 exposure was calculated using the health risk assessment method. The SO2 concentrations between 3.14 and 18.24 mg/m3. All sample points were above the quality standard threshold set by the EPA of 1.97 mg/m3. The most common health complaints workers experienced were eye irritation and coughing while working, followed by headache, shortness of breath, and skin irritation. The HQ index of SO2 exposure in workers was 1.02 for real-time exposure and 2.15 for long-term exposure. An HQ index ≥ 1 indicates a potential health risk for workers. Therefore, it is important to control workers' SO2 exposure.

Alteration of growth performance and characterization of pathological lesions in long-term ammonia-exposed pigs

Ammonia (NH3) is a major cause of odor emissions from swine farms, and exposure to high concentrations of NH3 in short-term periods has been reported to cause respiratory and systemic disorders in pigs. However, the impact of long-term NH3 exposure on pig health and productivity remain unknown. This study aimed to assess the impact of long-term NH3 exposure on growth performance and pathological outcomes in pigs. Pigs were reared in the treatment room [34.8 mg/m3 NH3 concentration (50 ppm); TRT group, n = 40] and the control room [5.6 mg/m3 (8 ppm); CON, n = 40]. The experimental period was 107 days (from weaning piglets to market age). Our findings revealed that long-term NH3 exposure results in severe respiratory and systemic pathological lesions, including chronic tracheitis, epithelial metaplasia of the trachea, severe interstitial pneumonia, myocarditis, and interstitial nephritis. In addition, the TRT group exhibited reduced productivity, with two deaths, indicating that uncontrolled NH3 concentrations on pig farms could be linked to a decline in growth performance and even death. Transcriptomic analysis revealed significant changes in immune and inflammatory pathways in lung from TRT pigs, including dysregulated cytokine signaling and incomplete inflammatory responses. The enrichment of DEGs in pathways, such as Cytokine-cytokine receptor interaction, JAK-STAT, and Toll-like receptor signaling, indicated chronic NH3 exposure disrupted immune homeostasis, contributing to chronic inflammation and impaired tissue repair. In conclusion, this study provides valuable insights into the detrimental effects of NH3 exposure on pig health and productivity under farm conditions.

Uncovering the features of industrial odors-derived environmental complaints and proactive countermeasures by using machine-learning

Industrial odor-derived environmental complaints pose an emerging and far-reaching challenge in cities worldwide with intensive industries. Developing effective odor complaint management strategies is essential for mitigating the public impact of industrial odors. Based on a typical case of persistent tire manufacturing odors affecting local communities, we proposed an environmental complaint risks (ECR) prediction model using machine-learning (ML) approaches, which combined complaints with temporal-resolution manufacturing-meteorology-environment data. Through intensive match-making between ML algorithms and multi-source parameters, Random Forest models can achieve a reliable ECR-prediction model performance with an average ROC-AUC of 0.79 at a monthly timescale, indicating the effectiveness of ML-based ECR prediction models. The interpretable ML model quantitively depicted the underlying mechanisms of ECR prediction, driven by process emission behaviors, local wind direction, and historical high-risk period. Furthermore, to mitigate predictable ECR within a future period, we designed a model framework that integrated ECR prediction models with an adaptive optimization genetic algorithm. This enabled the proactive management by precisely and dynamically allocating limited resources of emission regulatory to high-ECR periods in advance. The strategy was proven effective, achieving a significant 24.7% average reduction in the overall ECR forecast during a period with intensive complaints. Overall, this study proposed a data-driven model framework that efficiently helps the multi-stakeholders shift from passive response to proactive ECR management, thereby enhancing the environmental and social sustainability.

Migration of Chemical Compounds from Packaging Materials into Packaged Foods: Interaction, Mechanism, Assessment, and Regulations

The migration of chemical compounds from packaging polymers to food presents a multifaceted challenge with implications for food safety and public health. This review explores the interaction between packaging materials and food products, focusing on permeation, migration, and sorption processes. The different migration mechanisms of contact migration, gas phase migration, penetration migration, set-off migration, and condensation/distillation migration have been discussed comprehensively. The major migrating compounds are plasticizers, nanoparticles, antioxidants, light stabilizers, thermal stabilizers, monomers, oligomers, printing inks, and adhesives, posing potential health risks due to their association with endocrine disruption and carcinogenic effects. Advanced analytical methods help in the monitoring of migrated compounds, facilitating compliance with regulatory standards. Regulatory agencies enforce guidelines to limit migration, prompting the development of barrier coatings and safer packaging alternatives. Furthermore, there is a need to decipher the migration mechanism for mitigating it along with advancements in analytical techniques for monitoring the migration of compounds.

A highly efficient modified nano-activated carbon adsorbent for separation of ammonia from water: Experimental and kinetics elucidations

Water is essential for the survival of all living things; however, its extensive use in agriculture, high-tech manufacturing, energy production, and the rapid development of the chemical and petroleum industries has led to significant contamination, making water pollution a major concern today. Ammonia is one of the most harmful contaminants present in water, posing significant environmental and health risks that require appropriate remediation methods. To remove ammonia from contaminated water, we employ Carbon Nanotubes (CNTs) and Activated Carbon (AC). To ensure appropriate metal impregnation on the adsorbents, Fe, Al, Ag, and Cu were impregnated into both CNT and AC, followed by extensive characterization using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and Energy Dispersive X-rays (EDX). To optimize ammonia removal from water, several parameters were adjusted, including pH, dose amount, contact time, shaking speed, and temperature. Astonishingly, the highest removal efficiency of 40% was achieved with a 1 g dosage at pH 10.5 and 200 RPM, while silver oxide had a lower removal rate of 10% under the same conditions. Temperature additionally had a significant impact, with removal percentages reaching 40% at 70 °C as compared to 21.5% at 25 °C. Adsorption isotherms were used to analyze the experimental data, along with Langmuir and Freundlich's models. Notably, Langmuir produced superior curve fitting, resulting in a correlation factor close to one. Furthermore, kinetic modeling was carried out with 2nd-order and pseudo-2nd-order equations, with the latter responding better according to curve analysis. Because the ammonia removal rate was low, this study indicates the feasibility of implementing an adsorption technique using CNT and AC as a pre-treatment method for this purpose. This approach has the potential for future optimization and deployment in tackling water contamination concerns effectively.

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.

The screening evaluation of environmental odors: a new dispersion modelling-based tool

Odor pollution is the biggest source of complaints from citizens concerning environmental issues after noise. Often, the need for corrective actions is evaluated through simulations performed with atmospheric dispersion models. To save resources, air pollution control institutions perform a first-level odor impact assessment, for screening purposes. This is often based on Gaussian dispersion models (GDM), which does not need high computational power. However, their outputs tend to be conservative regarding the analyzed situation, rather than representative of the real in-site conditions. Hence, regulations and guidelines adopted at an institutional level for authorization/control purposes are based on Lagrangian particle dispersion models (LPDM). These models grant a more accurate simulation of the pollutants' dispersion even if they are more demanding regarding both technical skills and computing power. The present study aims to increase the accuracy of screening odor impact assessment by identifying the correlation function of the outputs derived from the two simulation models. The case study is placed in northern Italy, where a single-point source, with various stack heights, was considered. The case study is placed in northern Italy, where a single-point source, with various stack heights, was considered. The obtained correlation functions allow the practitioner to have a more accurate first-level odor impact assessment, to save time for training, and to reduce the site-specific meteorological data before proceeding with the simulation. The identified functions could allow institutions to estimate the results that would have been forecasted with the application of the more complex LPDM, applying, however, the much simpler GDM. This solution grants an accurate tool which can be used to address citizens' concerns while saving workforce and technical resources. Limitations are related to the specificity of the method regarding type sources, orography, and meteorological conditions. Comparison with other screening tools is also presented and discussed.

A critical review on characterization, human health risk assessment and mitigation of malodorous gaseous emission during the composting process

Composting has emerged as a suitable method to convert or transform organic waste including manure, green waste, and food waste into valuable products with several advantages, such as high efficiency, cost feasibility, and being environmentally friendly. However, volatile organic compounds (VOCs), mainly malodorous gases, are the major concern and challenges to overcome in facilitating composting. Ammonia (NH3) and volatile sulfur compounds (VSCs), including hydrogen sulfide (H2S), and methyl mercaptan (CH4S), primarily contributed to the malodorous gases emission during the entire composting process due to their low olfactory threshold. These compounds are mainly emitted at the thermophilic phase, accounting for over 70% of total gas emissions during the whole process, whereas methane (CH4) and nitrous oxide (N2O) are commonly detected during the mesophilic and cooling phases. Therefore, the human health risk assessment of malodorous gases using various indexes such as ECi (maximum exposure concentration for an individual volatile compound EC), HR (non-carcinogenic risk), and CR (carcinogenic risk) has been evaluated and discussed. Also, several strategies such as maintaining optimal operating conditions, and adding bulking agents and additives (e.g., biochar and zeolite) to reduce malodorous emissions have been pointed out and highlighted. Biochar has specific adsorption properties such as high surface area and high porosity and contains various functional groups that can adsorb up to 60%-70% of malodorous gases emitted from composting. Notably, biofiltration emerged as a resilient and cost-effective technique, achieving up to 90% reduction in malodorous gases at the end-of-pipe. This study offers a comprehensive insight into the characterization of malodorous emissions during composting. Additionally, it emphasizes the need to address these issues on a larger scale and provides a promising outlook for future research.

Using Hybrid PDI-Fe3O4 Nanoparticles for Capturing Aliphatic Alcohols: Halogen Bonding vs. Lone Pair-π Interactions

In this study, Fe3O4 nanoparticles (FeNPs) decorated with halogenated perylene diimides (PDIs) have been used for capturing VOCs (volatile organic compounds) through noncovalent binding. Concretely, we have used tetrachlorinated/brominated PDIs as well as a nonhalogenated PDI as a reference system. On the other hand, methanol, ethanol, propanol, and butanol were used as VOCs. Experimental studies along with theoretical calculations (the BP86-D3/def2-TZVPP level of theory) pointed to two possible and likely competitive binding modes (lone pair-π through the π-acidic surface of the PDI and a halogen bond via the σ-holes at the Cl/Br atoms). More in detail, thermal desorption (TD) experiments showed an increase in the VOC retention capacity upon increasing the length of the alkyl chain, suggesting a preference for the interaction with the PDI aromatic surface. In addition, the tetrachlorinated derivative showed larger VOC retention times compared to the tetrabrominated analog. These results were complemented by several state-of-the-art computational tools, such as the electrostatic surface potential analysis, the Quantum Theory of Atoms in Molecules (QTAIM), as well as the noncovalent interaction plot (NCIplot) visual index, which were helpful to rationalize the role of each interaction in the VOC···PDI recognition phenomena.

Environmental reporting in Italian thermal power plants: insights from a comprehensive analysis of EMAS environmental statements

The global energy sector heavily relies on fossil fuels, significantly contributing to climate change. The ambitious European emissions' reduction targets require sustainable processes and alternatives. This study presents a comprehensive analysis of 73 Italian thermal power plants registered to the European Eco-Management and Audit Scheme (EMAS) aimed at assessing EMAS effectiveness in addressing and quantifying the environmental impacts of this relevant industrial sector. The analysis was based on EMAS environmental statements, publicly disclosing verified and certified data, with the secondary objective of evaluating if EMAS could be an efficient tool to improve the plants' environmental performances. An inventory of technical and environmental aspects, adopted indicators, and allocated budgets was based on 2023 data. A strong correlation was found between the significance of the environmental aspects and the number of adopted indicators. Gaps were observed in describing aspects like "biodiversity" and "local issues". Improvement objectives and budget allocation showed discrepancies and lacked correlation with the significance of the related environmental aspects. "Energy production" accounted for 68% of the total allocated budget; "environmental risks", "emissions to air", "electricity consumption", and "local issues" were also key focus areas. Insufficient information on emission control technologies and progress tracking of improvement objectives was detected. This study highlights the need for thermal power installations to improve the selection of appropriate indicators and to better relate allocated budget to improvement objectives when implementing EMAS. Such measures would facilitate the quantification of the effective environmental impacts of the energy production sector, supporting future research on this topic, allowing stakeholders a better comparison among plants, and driving industry-wide improvements.

Derivation of human health and odor risk control values for soil ammonia nitrogen by incorporating solid-liquid partitioning, ammonium/ammonia equilibrium: A case study of a retired nitrogen fertilizer site in China

Nitrogen fertilizer supports agricultural intensification, but its manufacturing results in substantial contaminated sites. Ammonia nitrogen is the main specific pollutant in retired nitrogen fertilizer sites with potential human health and odor risks. However, few studies focus on ammonia nitrogen risk assessment at contaminated sites, particularly considering its solid-liquid partitioning process (Kd) and ammonium/ammonia equilibrium process (R) in the soil. This study took a closed nitrogen fertilizer factory site as an example and innovatively introduced Kd and R to scientifically assess the human health and odor risk of ammonia nitrogen. The risk control values (RCVs) of ammonia nitrogen based on human health and odor risk were also derived. The maximum concentration of ammonia nitrogen was 3380 mg/kg in the unsaturated soil, which was acceptable for human health because the health RCVs were 5589 ∼ 137,471 mg/kg in various scenarios. However, odor risk was unacceptable for RCVs were 296 ∼ 1111 mg/kg under excavation scenarios and 1118 ∼ 35,979 mg/kg under non-excavation scenarios. Of particular concern, introducing Kd and R in calculation increased the human health and odor RCVs by up to 27.92 times. Despite the advancements in ammonia risk assessment due to the introduction of Kd and R, odor risk during excavation remains a vital issue. These findings inform a more scientific assessment of soil ammonia risk at contaminated sites and provide valuable insights for the management and redevelopment of abandoned nitrogen fertilizer plant sites.

Deodorizing bacterial consortium: community analysis of biofilms and leachate water collected from an air biofiltration system in a piggery

Intensive livestock production is a source of water, soil, and air contamination. The first aspect that negatively affects the quality of life of residents in the vicinity of piggeries is malodorous aerosols, which are not only responsible for discomfort but can be an etiological factor in the development of various diseases during prolonged exposure. One of the proven and efficient ways to counteract odor emissions is the usage of air biofiltration. The purpose of this study was to qualitatively analyze the bacterial community colonizing the biofilm of a biofilter operating at an industrial piggery in Switzerland. The study material consisted of biofilm and leachate water samples. The microbiological analysis consisted of DNA isolation, amplification of the bacterial 16S rRNA gene fragment (V3-V4), preparation of a library for high-throughput sequencing, high-throughput NGS sequencing, filtering of the obtained sequencing reads, and evaluation of the species composition in the studied samples. The investigation revealed the presence of the following bacterial genera: Pseudochelatococcus, Methyloversatilis, Flexilinea, Deviosia, Chryseobacterium, Kribbia, Leadbetterella, Corynebacterium, Flavobacterium, Xantobacter, Tessaracoccus, Staphylococcus, Thiobacillus, Enhydrobacter, Proteiniclasticum, and Giesbergeria. Analysis of the microbial composition of biofilters provides the opportunity to improve the biofiltration process.

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.

Control of odorants in swine manure and food waste co-composting via zero-valent iron /H2O2 system

Odors have posed challenges to the advancement of aerobic composting. This work aims to identify the primary components responsible for odors and assess the effectiveness and mechanisms of the zero-valent iron/H2O2 system controlling various odorants in aerobic composting. Swine manure and food waste were used as composting materials, with the addition of zero-valent iron and hydrogen peroxide to mitigate odor emissions. Results revealed that odorants included ammonia, hydrogen sulfide, and 22 types of volatile organic compounds (VOCs), with ethyl acetate, heptane, and dimethyl disulfide being predominant. Among the odorants emitted, ammonia accounted for 75.43%, hydrogen sulfide for 0.09%, and identified VOCs for 24.48%. The ZVI/H2O2 system showed a significant reduction in ammonia and VOCs emission, with the reduction of 51% (ammonia) and 41.3% (VOCs) respectively, primarily observed during the thermophilic period. The occurrence of Fenton-like reactions and changes in key microbial populations were the main mechanisms accounting for odor control. The occurrence of Fenton-like reaction was confirmed by X-ray photoelectron spectroscopy and reactive oxygen detection, showing the oxidation of zero-valent iron by H2O2 to higher valence elemental iron, and the simultaneous production of ·OH. Microbial analysis indicated that an enrichment of specific microorganisms with Bacillus contributed to feammonx and Bacillaceae contributed to organic biodegradation. Redundancy analysis highlighted the role of key microbial species (Bacillaceae, Bacillus, and Ureibacillus) in effectively reducing the level of ammonia and volatile organic compounds. These novelty findings illustrated that the potential of this system is promising for controlling the emission of odorants and aerobic composting reinforcement.

Mixed-Linkage Donor-Acceptor Covalent Organic Framework as a Turn-On Fluorescent Sensor for Aliphatic Amines

Amine determination is crucial to our daily life, including the prevention of pollution, the treatment of certain disorders, and the evaluation of food quality. Herein, a mixed-linkage donor-acceptor covalent organic framework (named DSE-COF) was first constructed by the polymerization between 2,4-dihydroxybenzene-1,3,5-tricarbaldehyde (DTA) and 4,4'-(benzo[c][1,2,5]selenadiazole-4,7-diyl)dianiline (SEZ). DSE-COF displayed superior turn-on fluorescent responses to primary, secondary, and tertiary aliphatic amines, such as cadaverine, isopropylamine, sec-butylamine, cyclohexylamine, hexamethylenediamine, di-n-butylamine, and triethylamine in absolute acetonitrile than other organic species. Further experiments and theoretical calculations demonstrated that the combination of intramolecular charge transfer (ICT) and photoinduced electron transfer (PET) effects between the DSE-COF and aliphatic amines resulted in enhanced fluorescence. Credibly, DSE-COF can quantitatively detect cadaverine content in actual pork samples with satisfactory results. In addition, DSE-COF-based test papers could rapidly monitor cadaverine from real pork samples, manifesting the potential application of COFs in food quality inspection.

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.

Microbiome-metabolomics analysis reveals abatement effects of itaconic acid on odorous compound production in Arbor Acre broilers

BACKGROUND

Public complaints concerning odor emissions from intensive livestock and poultry farms continue to grow, as nauseous odorous compounds have adverse impacts on the environment and human health. Itaconic acid is a metabolite from the citric acid cycle of the host and shows volatile odor-reducing effects during animal production operations. However, the specific role of itaconic acid in decreasing intestinal odorous compound production remains unclear. A total of 360 one-day-old chicks were randomly divided into 6 treatment groups: control group (basal diet) and itaconic acid groups (basal diet + 2, 4, 6, 8 and 10 g/kg itaconic acid). The feeding experiment lasted for 42 d.

RESULTS

Dietary itaconic acid supplementation linearly and quadratically decreased (P < 0.05) the cecal concentrations of indole and skatole but did not affect (P > 0.05) those of lactic, acetic, propionic and butyric acids. The cecal microbial shift was significant in response to 6 g/kg itaconic acid supplementation, in that the abundances of Firmicutes, Ruminococcus and Clostridium were increased (P < 0.05), while those of Bacteroidetes, Escherichia-Shigella and Bacteroides were decreased (P < 0.05), indicative of increased microbial richness and diversity. Furthermore, a total of 35 significantly (P < 0.05) modified metabolites were obtained by metabolomic analysis. Itaconic acid decreased (P < 0.05) the levels of nicotinic acid, nicotinamide, glucose-6-phosphate, fumatic acid and malic acid and increased (P < 0.05) 5-methoxytroptomine, dodecanoic acid and stearic acid, which are connected with the glycolytic pathway, citrate acid cycle and tryptophan metabolism. Correlation analysis indicated significant correlations between the altered cecal microbiota and metabolites; Firmicutes, Ruminococcus and Clostridium were shown to be negatively correlated with indole and skatole production, while Bacteroidetes, Escherichia-Shigella and Bacteroides were positively correlated with indole and skatole production.

CONCLUSIONS

Itaconic acid decreased cecal indole and skatole levels and altered the microbiome and metabolome in favor of odorous compound reduction. These findings provide new insight into the role of itaconic acid and expand its application potential in broilers.

Non-negligible health risks caused by inhalation exposure to aldehydes and ketones during food waste treatments in megacity Shanghai

Aldehydes and ketones in urban air continue to receive regulatory and scientific attention for their environmental prevalence and potential health hazard. However, current knowledge of the health risks and losses caused by these pollutants in food waste (FW) treatment processes is still limited, especially under long-term exposure. Here, we presented the first comprehensive assessment of chronic exposure to 21 aldehydes and ketones in urban FW-air environments (e.g., storage site, mechanical dewatering, and composting) by coupling substantial measured data (383 samples) with Monte Carlo-based probabilistic health risk and impact assessment models. The results showed that acetaldehyde, acetone, 2-butanone and cyclohexanone were consistently the predominant pollutants, although the significant differences in pollution profiles across treatment sites and seasons (Adonis test, P < 0.001). According to the risk assessment results, the estimated cancer risk (CR; mean range: 1.6 × 10^-5-1.12 × 10^-4) and non-cancer risk (NCR; mean range: 2.98-22.7) triggered by aldehydes and ketones were both unacceptable in most cases (CR: 37.8%-99.3%; NCR: 54.2%-99.8%), and even reached the limit of concern to CR (1 × 10^-4) in some exposure scenarios (6.18%-16.9%). Application of DALYs (disability adjusted life years) as a metric for predicting the damage suggested that exposure of workers to aldehydes and ketones over 20 years of working in FW-air environments could result in 0.02-0.14 DALYs per person. Acetaldehyde was the most harmful constituent of all targeted pollutants, which contributed to the vast majority of health risks (>88%) and losses (>90%). This study highlights aldehydes and ketones in FW treatments may be the critical pollutants to pose inhalation risks.

Control of odor emissions from livestock farms: A review

Odor emission seriously affects human and animal health, and the ecological environment. Nevertheless, a systematic summary regarding the control technology for odor emissions in livestock breeding is currently lacking. This paper summarizes odor control technology, highlighting its applicability, advantages, and limitations, which can be used to evaluate and identify the most appropriate methods in livestock production management. Odor control technologies are divided into four categories: dietary manipulation (low-crude protein diet and enzyme additives in feed), in-housing management (separation of urine from feces, adsorbents used as litter additive, and indoor environment/manure surface spraying agent), manure management (semi-permeable membrane-covered, reactor composting, slurry cover, and slurry acidification), and end-of-pipe measures for air treatment (wet scrubbing of the exhaust air from animal houses and biofiltration of the exhaust air from animal houses or composting). Findings of this paper provide a theoretical basis for the application of odor control technology in livestock farms.

Impact of Bacillus subtilis on manure solids, odor, and microbiome

A study was conducted to determine the effectiveness of supplementing swine manure with Bacillus subtilis (BS) to improve digestion of manure solids and lower odor emission. Large bioreactors (400 L) with manure (100 L) were treated with commercially available BS at a rate of 1% manure volume by either directly pouring or surface spraying the manure with inoculum. Manure physicochemical properties, gas emissions, and microbiome were monitored. Manures treated multiple times with BS or surface sprayed had significantly (P < 0.05) lower electrical conductivity, volatile solids, and chemical oxygen demand, by 3-5% compared to non-treated control manures. Volatile sulfur compound emissions (VSCs) were reduced by 20-30% in both experiments, while ammonia and volatile organic compounds were reduced by 40% and 15%, respectively, in surface spray experiment only. The manure indigenous microbiome remained relatively stable following treatment and BS were never detected in the raw or treated manure following multiple treatments. The reduction in manure organic carbon and VSCs emissions were a result of physical mixing during manure treatment and biological material in the microbial inoculum stimulating microbial activity and not growth of BS.

Validation study of WindTrax reverse dispersion model coupled with a sensitivity analysis of model-specific settings

In last years, atmospheric dispersion models have reached considerable popularity in environmental research field. In this regard, given the difficulties associated to the estimation of emission rate for some kind of sources, and due to the importance of this parameter for the reliability of the results, Backward dispersion models may represent promising tools. In particular, by knowing a measured downwind concentration in ambient air, they provide a numerical value for the emission rate. This paper discusses a critical validation of the WindTrax Backward model: the investigation does not only deal with the strict reliability of the model but also assesses under which conditions (i.e. stability class, number, and location of the sensors) the model shows the greatest accuracy. For this purpose, WindTrax results have been compared to observed values obtained from available experimental datasets. In addition, a sensitivity study regarding model-specific parameters required by WindTrax to replicate the physics and the random nature of atmospheric dispersion processes is discussed. This is a crucial point, since, for these settings, indications on the numerical values to be adopted are not available. From this study, it turns out that the investigated model specific settings do not lead to a significant output variation. Concerning the validation study, a general tendency of the model to predict the observed values with a good level of accuracy has been observed, especially under neutral atmospheric conditions. In addition, it seems that WindTrax underestimates the emission rate during unstable stratification and overestimates during stable conditions. Finally, by the definition of alternative scenarios, in which only a portion of the concentration sensors was considered, WindTrax performance appears better than acceptable even with a small number of concentration sensors, as long as the positioning is in the middle of the plume and not in the strict vicinity of the source.

Volatile and semi-volatile organic compounds in landfill gas: Composition characteristics and health risks

Gas emitted from landfills contains a large quantity of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), some of which are carcinogenic, teratogenic, and mutagenic, thereby posing a serious threat to the health of landfill workers and nearby residents. However, the global hazards of VOCs and SVOCs in landfill gas to human health remain unclear. To quantify the global risk distributions of these pollutants, we collected the composition and concentration data of VOCs and SVOCs from 72 landfills in 20 countries from the core database of Web of Science and assessed their human health risks as well as analyzed their influencing factors. Organic compounds in landfill gas were found to primarily result from the biodegradation of natural organic waste or the emissions and volatilization of chemical products, with the concentration range of 1 × 10^-1-1 × 10⁶ μg/m3. The respiratory system, in particular, lung was the major target organ of VOCs and SVOCs, with additional adverse health impacts ranging from headache and allergies to lung cancer. Aromatic and halogenated compounds were the primary sources of health risk, while ethyl acetate and acetone from the biodegradation of natural organic waste also exceeded the acceptable levels for human health. Overall, VOCs and SVOCs affected residents within 1,000 m of landfills. Air temperature, relative humidity, air pressure, wind direction, and wind speed were the major factors that influenced the health risks of VOCs and SVOCs. Currently, landfill risk assessments of VOCs and SVOCs are primarily based on respiratory inhalation, with health risks due to other exposure routes remaining poorly elucidated. In addition, potential health risks due to the transport and transformation of landfill gas emitted into the atmosphere should be further studied.

Effects of fermented feed on growth performance, immune organ indices, serum biochemical parameters, cecal odorous compound production and the microbiota community in broilers

The aim of this study was to explore the effects of dietary fermented feed addition on growth performance, immune organ indices, serum biochemical parameters, cecal odorous compound production, and the bacterial community in broilers. A total of 480 broiler chicks (1-day-old) were randomly assigned to 6 groups, including a basal diet (control group), a basal diet supplemented with 10, 15, 20, and 25% dried fermented feed, and 10% wet fermented feed. Each group contained 8 replicates of 10 chicks each. The results showed that fermentation increased (P < 0.05) the total acid level and the number of Lactobacillus, Yeast, and Bacillus. The 15% dried fermented feed group had an increased (P < 0.05) body weight (BW) than the control, while the 25% dried fermented feed group had the lowest (P < 0.05) BW on 42 d. Compared to the control group, the feed intake (FI) was increased (P < 0.05) in the 10, 15% dried and 10% wet fermented feed groups from 22 to 42 d and from 1 to 42 d. No significant difference (P > 0.05) was observed in feed conversion ratio (FCR) among all groups. Supplementation with fermented feed increased (P < 0.05) the bursa of Fabricius index but not (P > 0.05) the thymus and spleen indices. Compared with the control, the broilers fed fermented feed had increased (P < 0.05) serum total protein, albumin, globulin, IgA, IgG, IgM, lysozyme, complement 3, and complement 4 levels. The cecal concentrations of acetic acid, propionic acid, butyric acid, and lactic acid were increased and the pH values were decreased in the fermented feed groups (P < 0.05). Among the groups, the 15% dried fermented feed group showed the lowest concentrations of skatole and indole in the cecum (P < 0.05). The composition of the cecal microbiota was characterized, in which an increased abundance of Ruminococcaceae, Lactobacillaceae, and unclassified Clostridiales and a decreased abundance of Rikenellaceae, Lachnospiraceae, and Bacteroidaceae were found in the fermented feed groups. Taken together, dietary fermented feed supplementation can improve growth performance, immune organ development, and capacity and decrease cecal odorous compound production, which may be related to the regulation of microbial composition.

Degradation of biogas in a simulated landfill cover soil at laboratory scale: Compositional changes of main components and volatile organic compounds

A laboratory experiment lasting 28 days was run to simulate a typical landfill system and to investigate the compositional changes affecting the main components (CH₄, CO₂, and H₂) and nonmethane volatile organic compounds from biogas generated by anaerobic digestion of food waste and passing through a soil column. Gas samples were periodically collected from both the digester headspace and the soil column at increasing distances from the biogas source. CH₄ and H₂ were efficiently degraded along the soil column. The isotopic values of δ¹³C measured in CH₄ and CO₂ from the soil column were relatively enriched in ¹³C compared to the biogas. Aromatics and alkanes were the most abundant groups in the biogas samples. Among these compounds, alkylated benzenes and long-chain C₃₊ alkanes were significantly degraded within the soil column, whereas benzene and short-chain alkanes were recalcitrant. Terpene and O-substituted compounds were relatively stable under oxidising conditions. Cyclic, alkene, S-substituted, and halogenated compounds, which exhibited minor amounts in the digester headspace, were virtually absent in the soil column. These results pointed out how many recalcitrant potentially toxic and polluting compounds tend to be relatively enriched along the soil column, claiming action to minimise diffuse landfill gas (LFG) emissions. The proposed experimental approach represents a reliable tool for investigating the attenuation capacities of landfill cover soils for LFG components and developing optimised covers by adopting proper soil treatments and operating conditions to improve their degradation efficiencies.

Artificial Olfactory Biohybrid System: An Evolving Sense of Smell

The olfactory system can detect and recognize tens of thousands of volatile organic compounds (VOCs) at low concentrations in complex environments. Bioelectronic nose (B-EN), which mimics olfactory systems, is becoming an emerging sensing technology for identifying VOCs with sensitivity and specificity. B-ENs integrate electronic sensors with bioreceptors and pattern recognition technologies to enable medical diagnosis, public security, environmental monitoring, and food safety. However, there is currently no commercially available B-EN on the market. Apart from the high selectivity and sensitivity necessary for volatile organic compound analysis, commercial B-ENs must overcome issues impacting sensor operation and other problems associated with odor localization. The emergence of nanotechnology has provided a novel research concept for addressing these problems. In this work, the structure and operational mechanisms of biomimetic olfactory systems are discussed, with an emphasis on the development and immobilization of materials. Various biosensor applications and current developments are reviewed. Challenges and opportunities for fulfilling the potential of artificial olfactory biohybrid systems in fundamental and practical research are investigated in greater depth.

Characteristics, secondary transformation and odor activity evaluation of VOCs emitted from municipal solid waste incineration power plant

Volatile organic compounds (VOCs) emitted from municipal solid waste incineration power plant (MSWIPP) plays a significant role in the formation of O₃ and PM_2.5 and odor pollution. Field test was performed on four MSWIPPs in an area of the North China Plain. Nonmethane hydrocarbons (NMHCs) and 102 VOCs were identified and quantified. Ozone formation potential (OFP), secondary organic aerosol formation potential (SOAFP), and odor activity of the detected VOCs were evaluated. Results showed that the average concentration of NMHCs and VOCs were 1648.6 ± 1290.4 μg/m³ and 635.3 ± 588.8 μg/m³, respectively. Aromatics (62.1%), O-VOCs (16.0%), and halo hydrocarbons (10.0%) were the main VOCs groups in the MSWIPP exhaust gas. VOCs emission factor of MSWIPP was 2.43 × 10³ ± 2.27 × 10³ ng/g-waste. The OFP and SOAFP of MSWIPP were 960.18 ± 2158.17 μg/m³ and 1.57 ± 3.38 μg/m³, respectively. Acrolein as the dominant VOC species was the major odor contributor with a percentage of odor contribution of 65.9%. Benzene and 1,2,4-trimethylbenzene as the dominant VOC species were the main contributors of O₃ formation potentials, in which 1,2,4-trimethylbenzene was also the main contributors of SOA formation potential.

Indicators for the sustainability assessment of MBR technologies for wastewater reuse in Chile: The good, the bad, and the ugly

While Chile faces a mega-drought, wastewater reuse emerges as an alternative solution. In this study we develop a set of indicators for the comprehensive sustainability assessment for the application of advanced wastewater treatment technologies (e.g., MBRs) in a wastewater reuse project in Chile. The methodology is based on the Integrative Concept of Sustainable Development (ICoS) framework. A critical analysis of the set of indicators is presented in terms of the benefits (The Good), the difficulties (The Bad), and the barriers (the Ugly) for their development and potential application. The characterization of the environmental benefits constitutes the useful aspects (e.g., recovery of nutrients, energy, and water). Difficulties include economic aspects (e.g., continuous monitoring of emerging contaminants) and public acceptance. Political and administrative aspects were found to be the main barrier, including water rights in Chile and the absence of a clear regulatory framework for wastewater reuse. To our knowledge, this study is the first to present a detailed methodology for developing indicators for membrane-based water reuse projects in Chile. The steps to develop the indicators are: •Identification of the study zone or case study, characterization of treatment technology.•Identification and formulation of indicators for the specific case study, based on the ICoS framework.•Verification of the relevance of indicators for the case study according to data availability and expert reviews.

Emission of volatile sulphur compounds during swine manure composting: Source identification, odour mitigation and assessment

This study aimed to identify the sources of volatile sulphur compounds (VSCs) and evaluate their mitigation by ferric oxide (Fe₂O₃) during swine manure composting. Four chemicals, including l-cysteine, l-methionine, sodium sulphite, and sodium sulphate, were further added to simulate organic and inorganic sulphur-containing substances in swine manure to track VSC sources during composting. Results show that sulphur simulants induced the emission of six common VSCs, including methyl sulphide (Me₂S), dimethyl sulphide (Me₂SS), carbonyl sulphide (COS), carbon disulphide (CS₂), methyl mercaptan (MeSH), and ethyl mercaptan (EtSH), during swine manure composting. Of them, COS, CS₂, MeSH and Me₂SS were predominantly contributed by the biodegradation of methionine and cysteine, while Me₂S and EtSH were dominated by the reduction of sulphite and sulphate. Further Fe₂O₃ addition at 1.5 % of total wet weight of composting materials immobilized elemental sulphur and inhibited sulphate reduction to reduce the emission of VSCs by 46.7-80.9 %. Furthermore, odour assessment indicated that adding Fe₂O₃ into composting piles significantly reduced the odour intensity level to below 4, the odour value of VSCs by 47.1-81.3 %, and thus the non-carcinogenic risk by 68.4 %.

Degradation of mixed typical odour gases via non-thermal plasma catalysis

The simultaneous treatment of H₂S and NH₃ typical odours by plasma was investigated and the co-treatment of both was found to have a facilitating effect the conversion. The degradation efficiency and by-product emissions of single plasma technology and plasma co-catalytic two-stage technology were compared and the degradation mechanism was further analyzed. The results show that in the single plasma technology conversion experiment, the conversion rate of the treated odours mixture is higher than that of the treated single odours, and the by-product emissions of SO₂ and NO_x are also reduced due to the reaction of intermediate products and by-products during the reaction process. The absolute removal of the odours mixture is optimal when treating at a gas flow rate of 6 L/min, a voltage of 16 kV and a frequency of 200 Hz. The M(Ce,Cu)-Mn/13X loaded catalyst was synthesized by co-precipitation method. Under the conditions of gas flow rate of 3-7 L/min, the efficiency of H₂S and NH₃ removal and the reduction of by-product emission were ranked as: uncatalyzed > Cu-Mn/13X > Ce-Mn/13X, which proved that Ce-Mn/13X showed better catalytic activity and application value.

Spatiotemporal footprints of odor compounds in megacity's food waste streams and policy implication

Odor pollution is one of the most critical issues in food waste (FW) recycling and has significant implications for human health. However, knowledge of their occurrence and spatiotemporally dynamic in urban FW streams is limited, making it not conducive to implement targeted odor management. This work followed the occurrence of 81 odor compounds (OCs) in nine FW-air environments along the Shanghai's FW streams for one year. Results showed that NH₃, acetic acid, acetaldehyde, acetone, 2-butanone, and methylene chloride were consistently the predominant OCs, despite the distinct differences in OCs profiles across seasons and treatment sites. Ridge regression and principal coordinate analysis demonstrated that seasons might play a non-negligible role in shaping odor profiles, and ambient temperature and humidity could account for the seasonal variation in OCs levels. Based on the modified fuzzy synthetic evaluation system, the screened priority pollutants in different FW-air environments were found broadly similar and the regulated air pollutants released via FW should be expanded to aldehyde and ketone compounds, especially for acetaldehyde. To our knowledge, this study is the first to track the spatiotemporal footprints of OCs within urban FW streams, and provides new insights into the control policy on FW-derived odor issues for megacities.

Pollution and Cleaning of PDMS Pervaporation Membranes after Recovering Ethyl Acetate from Aqueous Saline Solutions

The removal of volatile organic compounds (VOCs) from wastewater containing nonvolatile salts has become an important and interesting case of the application of the pervaporation (PV) process. The aim of this study was to evaluate the influence of salts on the PV removal of ethyl acetate from wastewater using a polydimethylsiloxane (PDMS) membrane. The fouled membrane was then characterized via scanning electron microscopy–energy-dispersive X-ray analysis (SEM–EDX) to investigate salt permeation. The membrane backflushing process was carried out by periodically flushing the permeate side of the tubular membrane. The results demonstrated that salts (NaCl and CaCl₂) could permeate through the PDMS membrane and were deposited on the permeate side. The presence of salts in the feed solution caused a slight increase in the membrane selectivity and a decrease in the permeate flux. The flux decreased with increasing salt concentration, and a notable effect occurred at higher feed-salt concentrations. A permeate flux of up to 98.3% of the original flux was recovered when the permeation time and backflushing duration were 30 and 5 min, respectively, indicating that the effect of salt deposition on flux reduction could be mitigated. Real, organic, saline wastewater was treated in a pilot plant, which further verified the feasibility of wastewater PV treatment.