Odor Emissions Research Articles

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.

Sensitivity analysis for odour dispersion modelling: LAPMOD evaluation and comparison with CALPUFF

Abstract Accurate dispersion modelling of odour emissions is essential for assessing their environmental impact on citizens. In this context, the sensitivity analysis of dispersion models is crucial for identifying the factors that most influence their predictions, thereby improving accuracy and reliability in environmental assessments. This study aims to perform a sensitivity analysis of the Lagrangian particle model LAPMOD, focusing on some key parameters including turbulent parametrization, meteorological data interpolation, plume rise algorithms, and concentration prediction kernels. It also compares LAPMOD results with CALPUFF results, one of the most widely applied models for regulatory purposes and odour impact assessments, to evaluate dissimilarities in odour impact predictions for both area and point sources. The analysis reveals that the choice of concentration estimation kernel has a significant impact on LAPMOD's predictions, with the Gaussian Kernel yielding the most consistent results. All other investigated input parameters show minimal influence, leading to variations in the results always below 15%. Concerning the comparison between models, while both models show quite consistent trends for point sources, LAPMOD tends to estimate significantly lower odour impacts from area sources compared to CALPUFF, with estimated separation distances differing up to a factor of 4 between the two models.

Odor Emissions from Municipal Solid Waste Open Dumps Constituting Health Problems Due to their Composition, Ecological Impacts and Potential Health Risks

The presence of Hydrogen sulfide, Methane, Volatile Organic Compounds (VOCs), and other odorous compounds in the ambient air is the root cause of the offensive odor emitting from the MSW dumping yard. Composition features and health risks associated with odor emissions concentrations in MSW dumping yards. This paper aims to provide an overview of research on health problems due to their composition, ecological impacts, and potential health risks of volatile organic compounds (VOCs) and to examine the relationship between VOC exposure and chronic illnesses in humans and the environment. In this study, a comprehensive investigation of VOC odor emission from an urban MSW dumping site has been performed. The VOC odor sample was analyzed using the GC-MS technique. The maximum VOCs concentration reported is due to tert - butylbenzene at 1.41μg.m-3 and the minimum is due to Sec-butylbenzene at 0.07 μg.m-3. Scientific databases, including Google Scholar, California Office of Environmental Health Hazard Assessment (OEHHA), and US EPA (Integrated Risk Information System (IRIS), were searched extensively using a bibliographic technique, in addition to a case study on MSW dumping yard workers. The findings of epidemiologic and experimental research, the emission of odors as a result of volatile organic compounds (VOCs) can cause a variety of non-cancerous health effects that are linked to abnormal functioning of the body’s vital organs, including the nervous and coronary, and pulmonary systems. It can also have minimal impact on the environment by causing global warming and ozone layer depletion. The odor emissions from the dumpsite pose both carcinogenic and noncarcinogenic risks to the health of the individuals participating in the dumping yard. As a result of these results, it is important to manage odor emissions (VOCs) during composting and take steps to reduce their negative effects on the environment and public health.

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.

Contribution and Mechanisms of BVOCs Emitted From a Typical Large Lake With Algal Bloom to O3 Levels in Lakeside Urban Areas

AbstractLakes near developed cities often experience algal blooms due to eutrophication, leading to odor and biogenic emissions that can potentially interfere with the formation of air pollutants such as O3 around these lakes. However, the impact and its pathways remain poorly understood. This study investigates the contributions of biogenic volatile organic compound (BVOC) emissions from Lake Taihu to O3 formation in surrounding regions using a numerical approach. Composite analysis, case studies, and process analysis reveal that BVOC emissions from Lake Taihu increase hourly near‐surface O3 concentrations, with a maximum rise of 25.5 μg m−3, improving model performance. The influence of lake BVOC emissions is large on the northwest side of Lake Taihu, primarily determined by the spatial emission patterns and dominant wind fields. The development of the planetary boundary layer, particularly the thermal internal boundary layer, and the enhanced lake breeze play important roles in increasing near‐surface O3 levels over land, whereas variations in temperature play a minor role. Vertical cross‐sections show that interactions between land‐lake breezes and background wind fields are critical for O3 transport, increasing surface concentrations in surrounding areas. Additionally, lake BVOC emissions intensify both daytime and nighttime gas‐phase chemical formation of O3, consuming nitrates and producing additional O3 within the lower troposphere. This study highlights the importance of local thermal circulations and lake BVOC emissions in O3 pollution, emphasizing the need for comprehensive air pollution control strategies in lakeside cities.

The Technical and Administrative Feasibility of Bokashi Composting as a Solution for Food Waste Treatment in a Typical North American Educational Facility Setting

Food waste is a nationwide problem in the US, leading to environmental concerns. A fermentation-based composting method, the Bokashi compost method, is proposed to mitigate the negative consequences of food waste (FW) disposal in educational facility settings. Bokashi utilizes fermentation to break down large molecular compounds in FW and convert them into compost. It presents several theoretical advantages over the currently widespread landfill methods. This method was subsequently examined for its technical and administrative feasibility and value through experiments and data analysis. Technically, the composting process can break down FW without defects such as odor emission, and produce compost with nutritional value for agricultural use; Administratively, the Bokashi composting method is found to be slightly less economical than the conventional landfill method. A typical high school has the capacity to process the FW generated, and there is a high likelihood of community cooperation. There is significant potential for scaling this model across educational facilities. However, studies on optimizing Bokashi workflow remain pending.

Up-Flow Anaerobic Sludge Bed Reactors for Sustainable Wastewater Management: Challenges, Innovations, and Future Directions

The up-flow anaerobic sludge bed (UASB) reactor is a high-efficiency system capable of carrying out anaerobic digestion with shorter hydraulic retention times than traditional anaerobic digesters. This review highlights recent advancements in UASB reactor applications and key aspects such as microbial community dynamics and reactor hydrodynamics that could drive future developments. More specifically, this review evaluates the working principles of UASB reactors, explores strategies to optimize reactor efficiency, and examines technological advancements aimed at overcoming temperature constraints, managing emerging pollutants and micropollutants, and addressing scum accumulation, odor emission, and nutrient recycling challenges. Furthermore, it addresses concerns about the lack of a skilled workforce and energy loss in biomethane. The UASB reactor demonstrates high potential for enhancing global wastewater management while holding the promises of enhancing circular economic objectives, promoting efficient biogas utilization, and reducing greenhouse gas emissions.

Odour prevention strategies in wastewater treatment and composting plants: A review.

Odour prevention strategies in wastewater treatment and composting plants: A review.

Biofiltration for odor mitigation in water resource recovery facilities.

Biofiltration for odor mitigation in water resource recovery facilities.

Machine learning-based prediction for airflow velocity in unpressured water-conveyance tunnels

Spillway and drainage tunnels have an open-channel flow pattern when operating under unpressured condition, above which air flow is driven and resisted by water flow, wall friction, and pressure difference. Unpressured tunnels present many airflow-related safety and environmental issues, including water flow fluctuation, gate vibration, shaft cover blow-off, and odor emission; therefore, it is valuable to study and predict their airflow velocity. Given the difficulty in accurate prediction of airflow velocity in unpressured tunnels and complicated influences of hydraulic, structural, and boundary pressure parameters, this study focuses on establishing high-performance prediction models and understanding the importance and independent and coupled influences of each parameter using machine learning. It is found that the water Froude number, ratio of free-surface width to unwetted perimeter, relative ventilation area, and relative tunnel length are four key parameters. By including these parameters in the input parameter combination, the machine learning models can well predict the airflow velocity in unpressured tunnels, achieving significantly higher performance than the existing empirical and theoretical models. Among these models, the models built by Random Forest and XGBoost demonstrate best performance with R2 ≥ 0.911. The interpretability analysis reveals the highest importance of the water Froude number and the ratio of free-surface width to unwetted perimeter, increases in which generally result in enhancement of the airflow velocity. The water Froude number plays a dominant role when it is ≤11.5, and a continuous increase exhibits a significantly marginal effect. The relative ventilation area and relative length of tunnels have close importances, with an increase in either generally promoting the airflow velocity. To help researchers and engineers unfamiliar with machine learning to easily and accurately predict the airflow velocity in unpressured tunnels, GPlearn algorithm is employed to establish explicit expressions, which is validated to have good performance with R2 close to 0.900.

A critical review of sulfide and methane control in urban sewer systems using nitrogen compounds.

Sewer gases, primarily hydrogen sulfide and methane, are detrimental to the wastewater infrastructure and environment by causing odour, corrosion, and greenhouse gas emissions. This article critically reviewed the dosing strategies, working mechanisms and effectiveness of widely used nitrogen compounds including nitrate, nitrite, free nitrous acid (FNA), free ammonia (FA), and organic silicon quaternary ammonium salt (QSA) in mitigating sewer emissions. Nitrate and nitrite play pivotal roles in increasing redox potentials and introducing microbial sulfide and methane oxidation. FNA and FA, known for their potent inhibitory and biocidal properties, effectively reduce sulfate reduction and methane production by disrupting cell membranes, altering intracellular pH, and blocking metabolic pathways. A systematic summary of the control effectiveness and associated change of microbial community were conducted based on different dosing strategies involving continuous or intermittent dosing patterns with constant, diurnal, dynamic and shock concentration profiles. Beyond their effectiveness in controlling emissions, nitrogen compounds like nitrite and FNA are effective in mitigating sewer concrete corrosion but also raise concerns about potential nitrous oxide (N2O) emissions. The innovative use of urine to produce FNA and FA may lead to a closed-loop strategy to achieve sustainable sewer emission control. This comprehensive review covering the dosing strategies, mechanisms, and effectiveness of nitrogen compounds will support the further development and optimal implementation.

Deciphering the driving mechanism of microbial community for rapid stabilization and lignocellulose degradation during waste semi-aerobic bioreactor landfilling with multifunctional microbial inoculum.

Deciphering the driving mechanism of microbial community for rapid stabilization and lignocellulose degradation during waste semi-aerobic bioreactor landfilling with multifunctional microbial inoculum.

Odorous Emissions During the Use of the Intermediate Fraction as an Additive to the Green Waste Composting Process

Composting is a key component of sustainable development strategies, as it supports ecological waste management, minimises the impact of human activities on the environment, and promotes the efficient use of natural resources. Reducing the generation of additional waste—as “recirculation” of composted waste—is also an important indicator of sustainability processes. The intermediate fraction (IF) is the material within the 10 mm to 60–90 mm range. It can be incorporated into composting materials to enhance the composting process. Maintaining an appropriate proportion of this fraction in the compost mixture is crucial for its practical use. This research examined the impact of adding the IF to composting on reducing the release of odorous substances. Additionally, it aimed to optimise the composting process by effectively managing the fraction. Optimisation sought to achieve high-quality compost, minimise odour emissions, and enhance the overall efficiency of the process. The study enabled the selection of the optimal variant—adding 9% of IF with inoculum—considering both ammonia emissions and odour impact. This variant yielded 13% less ammonia and 37% less odour than the variant without additives. This included identifying the intermediate fraction’s ideal proportion and adding pre-composted waste to compost piles.

Effects of different levels of dietary crude protein on growth performance, blood profiles, nutrient digestibility, pork quality and odor emission in growing-finishing pigs

Effects of different levels of dietary crude protein on growth performance, blood profiles, nutrient digestibility, pork quality and odor emission in growing-finishing pigs

Odour emissions from anaerobically co-digested biosolids: Identification of volatile organic and sulfur compounds.

Odour emissions from anaerobically co-digested biosolids: Identification of volatile organic and sulfur compounds.

Odour emissions from agricultural industries – implications for environmental safety and local sustainability

Odour emissions from agricultural industries – implications for environmental safety and local sustainability

Estimation of odor emissions from area sources using inverse modeling

Estimation of odor emissions from area sources using inverse modeling

Uso de biocatalisadores bovino, equino e caprino na compostagem de resíduos orgânicos provenientes de uma Unidade de Alimentação e Nutrição Escolar

The aim of the research was to evaluate the use of bovine, equine and caprine biocatalysts in the composting process to treat organic waste from a school in São Luís/MA, in order to assess the performance of the composting process and the quality of the organic compost generated. To this end, 03 composting beds were set up (adapted from the "Windrow" bed system), where the volume was calculated according to the carbon/nitrogen ratio. Each bed contained bovine, equine and caprine biocatalyst, waste generated in the school restaurant and tree and grass prunings. The food waste was quantified and classified. The lack of environmentally appropriate management of organic waste in school food and nutrition units results in the emission of unpleasant odors, favors the proliferation of disease vectors and contributes to the emission of methane, which intensifies global warming. Composting is one of the alternatives for treating organic waste, as it can reduce its volume by more than 60%, producing a stable material to be used as a soil conditioner. As a result, it was found that composting with school waste and using bovine, equine and caprine biocatalysts performed well, as the parameters of Organic Matter; pH; Phosphorus; Potassium, Calcium; Magnesium; Sodium; Aluminum; CTC and Base Saturation (V%) were in accordance with the values allowed in the literature. Therefore, the use of bovine, equine and caprine biocatalysts benefits the process of recycling animal manure and organic waste, generating quality compost.

Modified Biochar Adsorption Combined with Alkaline Solution Absorption for Sulfur-Containing Odor Gases Removal from Domestic Waste Transfer Stations

Odor emission has become a major issue in waste transfer stations. Hydrogen sulfide, methyl mercaptan (MM), and dimethyl disulfide (DMDS) are the main odorous gases. They have a low odor threshold and are difficult to remove. In this study, pine bark biochar was produced and modified with metal ions, including Ni2+, Ti2+, Mn2+, Zn2+, Mg2+, and Cu2+. It was then used for the removal of hydrogen sulfide, methyl mercaptan, and dimethyl disulfide. Among all modifications, the Cu2+ modified biochar showed the best sorption capacity, and the maximum sorption amounts were 20.50 mg/g for H2S, 36.50 mg/g for MM, and 57.98 mg/g for DMDS. To understand the adsorption, BET, SEM, and XPS of the original and modified biochar were performed. This illustrated that modification with Cu2+ increased the surface area and porosity, thus enhancing the adsorption capacity. In the alkaline absorption study, it was found that the removal of the three odor gases increased with the pH increase. Based on the results, a combined process called absorption–adsorption was established to treat the odor gas generated in a local waste transfer station. Thirty-one gas components were detected in the odor gas of the waste transfer station. The process proceeded for 30 days, and these gas components were not found in the effluent during treatment. Regarding H2S, MM, and DMDS, they were not detected even after 90 days. This indicates the high adsorption capacity of the modified biochar toward the three odor gases. In addition, the process is simple and easy to operate. This suggests that it is suitable for treating odor in places where there is no technician, and the odor needs efficient treatment. The study provides a feasible alternative for domestic waste transfer stations to control the odor problem.

Functional Feed for Laying Hens: Application of Saffron Extract as Eco-Friendly Supplement With Cholesterol-Lowering Properties.

Saffron has been utilized in numerous studies as an additive to augment egg quality and to enhance the oxidative stability of egg yolk.However, there is limited knowledge on the responses of hens to dietary supplementation with saffron petals on egg chemical composition, fecal mineral excretion, and ammonia emission. The objective of this study was to investigate the influence of saffron petal extract-enriched diet on egg quality, blood metabolites and odorous gas emission from excreta in laying hens. The experimental methodology involved a feeding trial conducted over a period of 12 weeks, using 200 Hy-line W36 laying hens aged 39 weeks. The dietary intervention included a basic diet (serving as a control with no supplementation), as well as diets fortified with 40, 60 or 80 parts per million (ppm) of hydroalcoholic saffron petal extract in a completely randomized design. Results showed that the inclusion of saffron petal extract in the diet did not significantly affect the egg crude protein, fat and ash content. However, a significant reduction (p<0.05) in yolk cholesterol concentration was observed. No substantial effect was noted on feed intake, feed conversion ratio (FCR) and egg weight (p>0.05). On the other hand, a significant increase (p<0.05) was documented in the egg production percentage of hens fed on the 80ppm saffron petal extract diet compared to the control. Furthermore, saffron petal extract supplementation resulted in a significantly lower yolk cholesterol together with reduced serum cholesterol content (p<0.05). Blood glucose and triglyceride concentrations also demonstrated a decrease subsequent to the inclusion of 80ppm saffron petal extract. The excretion of faecal minerals did not show any significant alterations due to the dietary interventions (p>0.05). Notably, hens supplemented with 60 and 80ppm saffron petal extract displayed significantly diminished concentrations of faecal ammonia (NH3) emissions (p<0.05) compared to the control. The study suggests that the inclusion of 80ppm saffron petal extract in the diet of laying hens may serve as a functional food source to mitigate cholesterol levels in egg yolk and blood serum, as well as to reduce faecal ammonia emissions.