The odors emitted from wastewater treatment plants are not only a health and hygiene problem, but can also lead to complaints from residents and have wider social ramifications such as bringing about falling property values in the surrounding area. In this paper, based on the data measured at domestic and overseas wastewater treatment facilities, the concentrations of complex odors and odorous compounds were compared for each treatment/process: primary treatment, secondary treatment, and sludge treatment processes. Odor compounds that contribute greatly to complex odors were summarized for each process. In addition, the characteristics of odor wheels for each wastewater treatment process, which provide both chemical and olfactory information regarding odors, were reviewed. For domestic wastewater treatment facilities, the complex odor concentrations (unit, dilution factor) of the primary and secondary treatment processes were 4.5-100,000 (median, 32.1) and 2.5-30,000 (median, 10.7), respectively. However, the complex odor concentrations in the sludge treatment process were 3.0-100,000 (median, 118.7), which was more than three times higher than that in the wastewater treatment process. In the wastewater treatment process, those odor compounds making the greatest contributions to complex odors were sulfur-containing compounds such as hydrogen sulfide, dimethyl sulfide, and dimethyl disulfide DMS. In order to properly manage odors from wastewater treatment plants and minimize their impact, it is important to understand the status of odor emissions. Therefore, the compositions and concentrations of odors from wastewater treatment processes and odor wheel information, which are reviewed in this paper, are used to evaluate the potential risk of odor from wastewater treatment facilities in order to derive strategies to minimize odor emissions. Moreover, the information can be usefully used to introduce the best available technology to reduce odors emitted from wastewater treatment facilities.

Odor is a type of air pollution where irritating substances enter through the olfactory system, causing discomfort. At present, the government is formulating various measures and policies to address this type of pollution. This paper seeks to analyze major research cases from both domestic and overseas settings in relation to odor management. In addition, it reviews the potential of addressing environmental issues using a living lab approach in conjunction with community mapping and citizen science. For example, in one domestic case, the Magok smart city living lab project, citizens’ data on community mapping of odor were collected for analysis using artificial intelligence (AI) to derive results. Additionally, in an overseas case in California, citizens directly participated in monitoring air quality using the Community-based monitoring (CBM) method, and both CBM and existing methods were used to assess the level of pollutants for effective data collection. In both of these cases, the potential to address environmental issues was seen to manifest through the development of citizens’ determination and ability to independently solve local problems. However, there are still problems in implementing citizen science, such as the lack of infrastructure and resources available, issues with data collection methodology, questions of objectivity regarding collected data, and concerns about sustainability and expertise in relation to civic participation. Addressing these problems would require an institutional foundation and systematic civic education. This study highlights the potential of addressing environmental problems inherent in the living lab system based on citizen science by analyzing two cases. In addition, this study suggests that if systematic civic education measures are introduced to address issues within existing citizen science research approaches, such measures would be valuable within the educational living lab framework in that they would become effective in tackling not only environmental problems but also social problems as well.

This review paper aimed to comprehensively assess the ventilation methods and ventilation rates of livestock sheds, various livestock odor mitigation technologies, and the design flow rate of odor mitigation devices. The most efficient ventilation method for livestock odor control was found to be mechanical ventilation. When livestock odor is at its most severe during summer, ventilation systems are operated at the maximum ventilation rate, which is 5-25 times higher than the ventilation rate in winter. Therefore, the mitigation facilities of livestock odor must be designed while considering the maximum ventilation rate. There is a significant amount of research data on various livestock odor control technologies using various physical, chemical, biological, and complex technologies applied to livestock farms. Biofiltration and photocatalytic oxidation are considered the most promising methods due to their cost-effectiveness and simplicity. Biofiltration is effective for removing hydrophilic odors, but requires improvement for the efficient removal of hydrophobic odors and the control of accumulated excess biomass. The advantages of the photocatalytic oxidation method include its excellent hydrogen sulfide and ammonia removal rates and relatively low ozone emissions. However, it requires technology to reduce nitrous oxide emissions. Investment in installing and operating these odor mitigation technologies is only realistic for large-sized farms. Therefore, it is imperative for small and medium-sized livestock farms to develop odor mitigation technology that is inexpensive and has low installation, operation, and maintenance costs.

This review comprehensively summarizes the livestock odor reduction method by dietary manipulation, in-housing management, and manure management. The gut microbial metabolism of animals can be stimulated by low-crude protein feeding and the addition of probiotics, enzymes, plant extracts, and/or organic acids to their feed. These methods can result in reduced odor emissions from manure. For in-housing management, it is important to maintain the proper breeding density in the barn facilities, regularly remove dust and manure, and periodically clean the barn facilities. A barn using litter on the floor can reduce odor at a relatively low cost by adding adsorbents such as zeolite, biochar, etc. Although masking agent spraying can be the simplest and quickest way to control odors, it is not a fundamental odor mitigation strategy. Odor emissions can be reduced by installing covers on manure slurry storage facilities or by acidifying the manure slurry. It is necessary to install a solid-liquid separator in an enclosed facility to minimize odor emissions. Other methods for reducing odor emissions include covering manure composting plants with semi-permeable membranes or using reactor composting technology. In order to minimize odor emissions in the liquid manure composting, sufficient oxygen must be supplied during the fermentation process. Furthermore, the odor reduction effect can be achieved through the liquid manure pit recharge system which supplies matured liquid manure fertilizer to the slurry pit in the pig house.

In this review paper, the sources of odor, major odor compounds, and emission characteristics from livestock farms are summarized. The main sources of odor on livestock farms are barn facilities, manure storage facilities, manure composting facilities, and wastewater treatment facilities. High concentrations of odor are emitted during the manure removal process, and livestock odor tends to be the most severe in summer. There was a remarkable difference in odor intensity depending on the farm size and the cleaning condition, and odor intensity varied greatly depending on the weather parameters such as wind direction and speed. The concentrations of ammonia and hydrogen sulfide were high among the odor compounds emitted from livestock farms, and these compounds also contributed to odor intensity. The odor intensity in poultry and swine farms was higher than in cattle farms. Information on livestock odor emission is very useful for managing livestock odor complaints and designing odor abatement technologies.

The livestock industry continues to grow around the world, but livestock odor is becoming an environmental problem that is difficult to solve. In this review paper, the current status of the domestic livestock industry, livestock odor complaints, mediation cases involving environmental disputes related to livestock odor, livestock odor management policies and standards, livestock odor sources, major odor compounds, and emission characteristics are summarized. Domestic meat supply and meat consumption per capita are increasing, and livestock farms are becoming large-scale and intensive. Livestock odor complaints increased 4.5 times over the last five years (2014-2019), and its proportion to total odor complaints was 19%-30%. Livestock facilities larger than a certain size are classified as odor emission facilities and are managed based on the Odor Prevention Act. The information presented in this paper can be used to establish strategies to promote the sustainable development of the livestock industry while resolving air quality deterioration and public health problems caused by odor emissions from livestock farms.

As the demand for the monitoring of VOCs increases, various unpowered colorimetric sensors are being developed, but the performance evaluation method of the developed sensors has not been systematically established. In this study, the device, experimental process, and data calculation methods for the performance evaluation of the colorimetric sensors were proposed. An aluminum chamber (70W× 128 L × 40 mm H) was designed to expose the sensor to a constant concentration of VOCs. In addition, an experimental apparatus was devised to evaluate the effect of environmental factors (temperature and humidity) affecting the ability of the sensor to detect VOCs. To calculate the color change value of the sensor corresponding to the concentration of VOCs, the ‘peak wavelength method’ that analyzes the wavelength of the highest intensity for high-concentration VOCs and the ‘spectral centroid method’ using a weighted arithmetic average for low-concentration VOCs were used. As a result of evaluating the ability of the colorimetric sensor to detect VOCs, which was made of polydimethylsiloxane (PMDS) by the method proposed in this study, the wavelength change values (bandgap shift) of the sensor for 1,000 ppm of benzene, toluene, oxylene, and acetone were 0.898 nm, 2.304 nm, 5.775 nm, and 0.249 nm, respectively. The precision was calculated by repeatedly measuring the sensing ability of the sensor 5 times for each type of VOCs. The precision of the sensor responses to benzene, toluene, o-xylene, and acetone were 15.23%, 7.84%, 4.14%, and 30.00% RSD, respectively. The method proposed in this study can be used to evaluate the performance of various types of VOCs colorimetric sensors.

Cooking, especially meat and fish grilling, is one of the representative sources of indoor and outdoor particulate matter (PM). Most of PM emitted from cooking is ultrafine dust (PM2.5). Since odorous organic acids, aldehydes, and volatile organic compounds are absorbed by PM and discharged, restaurants and food service industries are major sources of odorous PM emission that cause odor nuisance complaints in cities. PM emitted from cooking also contains polycyclic aromatic hydrocarbons (PAHs), which are carcinogens. In this paper, the domestic PM emission status of biomass combustion, especially meat and fish grilling, was analyzed temporally and spatially. The results of previous studies on PM emission concentrations, emission rates, emission factors and their compositions from cooking were comprehensively summarized. In addition, the effects of food ingredient types, cooking methods, seasoning and oil addition and fuel types on the PM emission were reviewed. Much more PM was produced when cooking with charcoal rather than electricity or gas. The higher the fat content of food ingredients such as intestines, the higher the PM emission concentration and emission rate. There was a difference in the PM emissions depending on the cooking oil types, and the PM emission concentration was high when olive oil or corn oil was used. It is necessary to accumulate more information through followup studies on the emission concentrations, emission factors and properties of PM emitted from cooking activities. This information can be used for controlling odorous PM in restaurants and food service industries, and predicting the impacts of odorous PM on air quality and human health.

The emission of particulate matter and volatile organic compounds (VOCs) from a motor vehicle painting booth was quantitatively evaluated. Most particulate matter was emitted during the spraying process, in which the PM10 concentration was 16.5 times higher than that of the drying process. When the paint was being sprayed, the particles with a diameter of 1.0~2.5 μm accounted for 39.4% and particles greater than 2.5 μm in diameter accounted for 30.6% of total particles. On the other hand, small particles less than 0.5 μm in diameter accounted for 52.4% of total particles during the drying process. In contrast to the particulate matter, high concentrations of VOCs were emitted during both spraying and drying processes. Butyl acetate, xylene, toluene, and m-ethyltoluene were the most abundant VOCs emitted from the motor vehicle painting booth. Additionally, xylene, butyl acetate, toluene, and 1,2,3-trimethylbenzene were the dominant ozone precursors. Especially, xylene exhibited the highest ozone production contribution (32.5~44.4%) among 34 species of the ozone precursors. The information obtained in this study can be used to establish a suitable management strategy for air pollutants from motor vehicle painting booths.

n-Nonane, 1¸2¸4-trimethylbenzene (124-TMB), toluene, total xylene (TXYL), isopropyl alcohol (IPA), and methyl ethyl alcohol (MEK) are major volatile organic compounds (VOCs) emitted from printing industries. The absorption amount of a single VOC per unit weight of silicone oil was as follows in the order of 189.5 g/kg-silicone oil for n-nonane, 91.7 g/kg-silicone oil for 124-TMB, and 60.1 g/kg-silicone oil for TXYL. Although hydrophobic VOCs were more absorbed in silicone oil than hydrophilic VOCs such as IPA and MEK, IPA and MEK, which had log Kow values of 1 or less, also were absorbed more than 26.0 g/kg-silicone oil. In two and three mixed VOCs of n-nonane, 124-TMB, and toluene, the absorption amount of each in silicon oil was less than that of single a VOC. The total absorption amount of two mixed VOCs ranged from 47.9 g to 138.7 g/kg-silicone oil, and the total absorption amount of three mixed VOCs was 65.8 g/kg-silicone oil. These results suggest that silicone oil is a promising pretreatment solution capable of absorbing high concentrations of VOCs that are intermittently emitted from printing industries. The absorption information of VOCs obtained in this study can be used as the design parameters of a damping device for the pretreatment of VOCs.

Sulfide dissolved in wastewater is a potential source of hydrogen sulfide. Hydrogen sulfide is an odorous substance that causes civil complaints and is a dangerous substance that threatens the corrosion of structures and the safety and health of workers. The removal efficiencies of the chemical oxidant and the coagulants were compared to evaluate the removal of dissolved sulfide. Since the effectiveness may vary depending on the characteristics of the wastewater, water was used as a control, and 5 mg/L of dissolved sulfide was dissolved in water and sewage wastewater. When oxidant was used, the results showed a high sulfide removal rate in sewage wastewater than water, and the removal efficiency was enhanced with increasing oxidant concentration. Sulfide removal efficiencies after one hour after injecting oxidants H2O2, NaOCl, NaClO2 to sewage wastewater were 70%, 90%, and 100%, respectively. After the oxidants were administered four times, the removal was 90%, 100%, and 100%, respectively. In the case of sulfide removal with the oxidizing agent, the removal efficiency was NaClO2, NaOCl, H2O2 (highest - lowest). NaClO2 showed 100% removal efficiency within 10 minutes under all conditions (A condition, B condition), making it the most sewage effective agent in this study. In the case of the coagulants, 100% of the sulfides dissolved in water were removed in the first 10 minutes under all conditions. In sewage wastewater, FeCl2 and FeSO4 also showed 100% removal efficiency under all conditions after one hour, and FeCl3 showed 90% and 99% removal rates under A and B conditions, respectively. That is, the monovalent iron coagulants (FeCl2, FeSO4) were found to be somewhat more effective in the removal of sulfides in sewage wastewater than the divalent iron (FeCl3) coagulants. When the sulfides were removed with coagulants, FeCl2 had the highest removal efficiency followed by FeSO4 and FeCl3. Moreover, it was found that NaClO2 has the best reaction efficiency at the minimum reaction time and the reaction concentration.

This study was conducted to determine the absorption properties of silicone oil, liquid paraffin, and silicone rubber as absorbents for hydrophobic volatile organic compounds (VOCs) mainly emitted from the printing and publishing industry through VOCs absorption efficiency and partition coefficient. Also, changes in absorbability were tested through blending of absorbents and load of target VOCs mixtures. The results obtained can be used as fundamental data to choose an appropriate absorbent. All of the three absorbents showed an excellent absorption efficiency of above 98% for each 5 wt% load of the target VOCs including toluene, xylene, methyl ethyl ketone (MEK), isopropyl alcohol (IPA), 1,2,4-trimethylbenzene (124-TMB), and n-Nonane. In terms of toluene load, all absorbents showed good absorption efficiency of above 95% to a high load of 15 wt%. The air-absorbent partition coefficient of each target compound (P value) exhibited the highest value of 9.8 × 10−5 for 124-TMB in silicone rubber and the lowest value of 1.6 × 10−2 for IPA in liquid paraffin. These results indicate that the target VOCs had high affinity for the three absorbents. Absorption efficiency for the target VOCs at various absorbent blending ratios using three kinds of absorbents was improved to 99.9% regardless of the absorbent type or blending ratio. This result suggests that the shortcomings of single absorbents can be overcome through absorbent blending, enabling cost reduction and applicability to a dry-type treatment process. In treatment for mixture of the target VOCs to mimic an actual VOCs treatment, the absorption performances of silicone oil showed an absorption efficiency of 99% for 16 wt% of total VOCs load. These results indicated that silicone oil could be considered as a good absorbent.

A pilot-scale biocover was installed at a sanitary landfill for municipal waste, and the removal of volatile organic compounds (VOCs) by the biocover was evaluated for a long period of 550 days. The biocover (2.5 m W × 5 m L × 1 m H) was constructed with the mixture of soil, perlite, earthworm cast and compost (6:2:1:1, v/v). The total VOCs concentration of the inlet gas into the biocover was 820.3 ppb~7,217.9 ppb, and the total VOCs concentration of the outlet gas from the surface of the biocover was 12.6 ppb~1,270.1 ppb. The average removal efficiency of total VOCs was 87.6 ± 11.0% (60.5% for minimum and 98.5% for maximum). Toluene concentration was the highest among the inlet VOCs, followed by ethylbenzene, m, p-xylene and o-xylene. These aromatic VOCs accounted for more than 50% of the total VOCs concentration. Other than these aromatic VOCs, hexane, cyclohexane, heptane, benzene, and acetone were major VOCs among the inlet VOCs. Compared with the VOC profiles in the inlet gas, the relative contribution of dichloromethane to the outlet VOCs emitted from the biocover layer increased from 0.1% to 15.3%. The average removal efficiencies of BTEX in the biocover were over 84% during the operation period of 550 days. The average removal efficiencies of hexane, cyclohexane and heptane in the biocover were 86.0 ± 18.9%, 85.4 ± 20.4% and 97.1 ± 4.0%, respectively. The removal efficiency of VOCs in the biocover decreased not only when the ambient temperature had fallen below 5oC, but also when the ambient temperature had risen above 23oC. Information on the VOCs removal characteristics of the biocover installed in the landfill field can be useful for commercializing the biocover technology for the treatment of VOCs.

This paper is a review on the treatment of volatile organic compounds using absorbents. Volatile organic compounds (VOCs) are carbon-based compounds with a boiling point ranging from 50℃ to 250℃. VOCs have been considered as contributors of photochemical smog and global warming as well as hazards to human health. VOCs can be removed by a variety of methods, including those that are destructive (incineration, catalytic oxidation, and biodegradation) and non-destructive (adsorption, absorption, and condensation). The removal performance of VOCs in the gas phase is influenced by gas-liquid mass transfer and/or the microbial activity depending on VOC properties such as solubility, diffusivity, bioavailability, and toxicity. Since the usual processes for VOCs removal involve water as a VOC absorbent, it is necessary to improve the removal efficiency of hydrophobic VOCs. In addition, VOC removal processes do not appear to show consistently satisfactory performance due to transient high-strength VOC loading in practical fields. To increase the gas-liquid mass transfer of hydrophobic VOCs and to prevent the functional deterioration due to transient high loading, the use of nonaqueous phase VOC absorbents is a promising strategy. This review offers a critical overview of the types, properties, and the applications of the VOC absorbents, including liquid organic solvents, ionic liquids, and solid polymers. This paper also details the advantages by employing the VOC absorbents for the removal of hydrophobic VOCs in the integrated process, absorption and biodegradation coupling process. The challenges of and future perspectives on the development of efficient VOC removal processes using VOC absorbents are briefly discussed.

Seasonal emission characteristics of odors and methane were investigated throughout the period of 17 months in which the emission status of odors and methane from soil cover layers in a sanitary landfill was measured. Complex odor emitted from soil cover layers fluctuated largely at the range of 7~20,800 OU (Odor Unit) in odor dilution ratio, and the median and average values were 2,080 and 4,203 OU, respectively. The intensity of complex odor showed higher values in the spring (5,663 ± 4,033 OU) and winter (6,056 ± 8,372 OU) than in the summer (1,698 ± 3,676 OU) and fall (1,761 ± 451 OU). Based on average concentrations, the compounds with high contribution values for the sum of the odor quotient (SOQ) were hydrogen sulfide (46.1%), methyl mercaptan (26.4%), and dimethyl sulfide (16.8%). This result shows that sulfur compounds were the main odor-causing compounds in the target landfill. The flux of complex odor was 0.17~70.36 OU·m−2·min−1 (Median 0.47, Average 5.40), and the flux of hydrogen sulfide was 0~114.70 μg·m−2·min−1 (Median 0.13, Average 5.91). The methane flux was 0.59~312.70 mg-CH4·m−2·min−1 (Median 25.61, Average 47.99). The methane concentrations emitted at the soil cover layers showed the highest values of 1.0~62.5% (Median 33.0, Average 21.1) in the spring, and the lowest values of 0.1~11.7% (Median 2.3, Average 3.7) in the winter. The methane concentrations in the summer and fall were similar with the average of 17.9% (range of 0.2-44.2%) and 12.5% (range of 2.2-42.5%), respectively. The emission data of odors and methane from soil cover layers can be utilized to establish management policy and apply mitigation technologies for the control of odor and greenhouse gases emitted in landfills.

In order to reduce odor and methane emission from the landfill, open biocovers and a closed biofilter were applied to the landfill site. Three biocovers and the biofilter are suitable for relatively small-sized landfills with facilities that cannot resource methane into recovery due to small volumes of methane emission. Biocover-1 consists only of the soil of the landfill site while biocover-2 is mixed with the earthworm casts and artificial soil (perlite). The biofilter formed a bio-layer by adding mixed food waste compost as packing material of biocover-2. The removal efficiency decreased over time on biocover-1. However, biocover-2 and the biofilter showed stable odor removal efficiency. The rates of methane removal efficiency were in order of biofilter (94.9%)>, biocover-1(42.3%)>, and biocover-2 (37.0%). The methane removal efficiency over time in biocover-1 was gradually decreased. However, drastic efficiency decline was observed in biocover-2 due to the hardening process. As a result of overturning the surface soil where the hardening process was observed, methane removal efficiency increased again. The biofilter showed stable methane removal efficiency without degradation. The estimate methane oxidation rate in biocover- 1 was an average of 10.4%. Biocover-2 showed an efficiency of 46.3% after 25 days of forming biocover. However, due to hardening process efficiency dropped to 4.6%. After overturn of the surface soil, the rate subsequently increased to 17.9%, with an evaluated average of 12.5%.

The Automobile HVAC system is a habitat for odor-associated fungal communities. We investigated the odorassociated fungal community in an automobile HVAC system using a high-throughput DNA sequencing method. The fungal community structure was evaluated via metagenome analysis. At the phylum level, Ascomycota and Basidiomycota were detected, accounting for 43.41% and 56.49% of the fungal community in the HVAC system, respectively. Columnosphaeria (8.31%), Didymella (5.60%), Davidiella (5.50%), Microxyphium (4.24%), unclassified Pleosporales (2.90%), and Cladosporium (2.79%) were abundant at phylum of Ascomycota and Christiansenia (36.72%), Rhodotorula (10.48%), and Sporidiobolus (2.34%) were abundant at phylum of Basidiomycota. A total of 22 genera of fungi were isolated and identified from the evaporators of the HVAC systems which support fungal growth and biofilm formation. Among them, Cladosporium, Penicillium, Aspergillus and Alternaria are the most representative odor-associated fungi in HVAC systems. They were reported to form biofilm on the surface of HVAC systems with other bacteria by hypha. In addition, they produce various mVOCs such as 3-methyl-1-butanol, acetic acid, butanoic acid, and methyl isobutyl ketone. Our findings may be useful for extending the understanding of odor-associated fungal communities in automobile HVAC systems.

This study investigated the odor-associated bacterial community in automobile HVAC systems. Through a metagenome analysis, it was found that; Massilia (42.426%), Sphingomonas (28.200%), (10.780%), and Methylobacterium (5.756%) were abundant in the HVAC systems. Massilia can cause the biodegradation of polycyclic aromatic hydrocarbons (PAHs) producing odor in automobiles. Sphingomonas produces volatile halogenated compounds or degrades organic pollutants. Rhodococcus is reported to produce sulfur compounds which give off an odor similar to rotting eggs and cabbages. Methylobacterium is one of the most representative bacteria that causes odor in automobile HVAC systems. The evaporator is considered as the appropriate habitat for microorganisms in automobiles because of its high humidity and organic adsorption. Massilia, Sphingomonas, Rhodococcus, Methylobacterium, Bacillus, Staphylococcus, Arthrobacter, Micrococcus, and Pseudomonas, listed in order from most to least present, were isolated as abundant bacteria in the evaporator of the HVAC systems.

The purpose of this study was to investigate ash and mineral contents of agricultural products that are widely and specifically grown in Korea, including 23 fruits, 11 cereals and specialty crops, and 11 leaves and vegetables. Pre-treatment of mineral was performed by microwave method. Mineral contents were analyzed by Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) and Inductively Coupled Plasma Spectrophotometry Mass (ICP-MS). Ash contents ranged from 0.20 to 0.69 g/100 g in fruits, 1.62 to 3.80 g/100 g in cereals, and 0.28 to 2.93 g/100 g in leaves and vegetables. Among the 45 samples, the highest contents of ash were found in quinoa (average 3.80 g/100 g), the highest contents of calcium (Ca) were found in Hansan ramie leaves (average 894.79 mg/100 g), the highest contents of phosphorus (P) were found in yellow amaranth(average 661.88 mg/100 g), the highest contents of potassium (K) were found in quinoa (average 1,455.38 mg/100 g), the highest contents of magnesium (Mg) were found in red amaranth (average 434.02 mg/100 g), the highest contents of molybdenum (Mo) were found in moringa (average 482.50 μg/100 g), and the highest contents of selenium (Se) were found in apple mango(average 23.67 μg/100 g).