In this study, we analyzed the changes in concentrations of volatile fatty acids (VFA), phenols, and indoles, as well as odor contribution in pig slurry. The pig slurry was stored for approximately two months after the manure excretion of pigs which had been fed 3% level of peat moss additive. The investigation was carried out through lab-scale experiments simulating slurry pit conditions within pig house. Throughout the storage period, the concentration of VFA exhibited a tendency to be 11%-32% higher in the pig manure treated with peat moss as compared to the control group. From a concentration perspective, phenol and acetic acid accounted for the majority of the total odor compounds produced during the pig slurry storage period. However, their significance diminished when the concentration of odoros compounds are converted into odor activity value and odor contribution. Despite the odor reduction effect of the ammonia (NH3) adsorption by peat moss, if it cannot effectively reduce the high odor-contributing compounds such as indoles and p-cresol, the sole use of peat moss may not be considered an effective means of mitigating odors produced by pig slurry. According to this study, indoles, p-cresol, skatole, and valeric acid were consistently revealed as major odor-contributing substances during the two-month storage of pig slurry. Therefore, a comprehensive odor mitigation methodology should be proposed, taking into consideration the odor generation characteristics (including temporal concentration and odor contribution) of pig slurry-derived odors during storage.

In this study, the removal performance of high-concentration H2S and complex odors was evaluated for bio-filters installed in sewage treatment plants and manure treatment plants. The amount of odor generation according to temperature was found to be higher in summer than in spring. It was found that the longer the empty bed retention time of the bio-filter, the higher the odor removal efficiency. Therefore, in order to effectively remove odors, it is necessary to maintain a sufficiently long residence time when designing a bio-filter. In addition, a case in which a bio-filter and a wet pre-treatment system were combined to remove high-concentration odors was studied. The result showed that the wet pre-treatment was effective in removing high-concentration odors. In particular, most of the hydrogen sulfide could be adequately removed by wet pre-treatment.

Odor is a type of sensory pollution that can stimulate the human sense of smell when it occurs, causing discomfort and making it difficult to create a pleasant environment. For this reason, there is a high possibility of complaints regarding odors if odors occur in pigsties near residential properties, and the number of such complaints is also increasing. In addition, odors emanating from pigsties around military installations can cause physical and psychological harm, not only to the soldiers living in these type of facilities but also to the families belonging to military personnel living there as well. Because the concentration of odors varies due to diverse factors such as temperature, humidity, wind direction, wind speed, and interaction between causative materials, predicting odors based on only one factor is not proper or appropriate. Therefore, in this work, we sought to construct models that are based on several regression techniques of machine learning using data collected in field. And we selected and utilized the model that has the highest-accuracy in order to notify and warn residents of odors in advance. In this work, 3672 data items were used to train and test the model. The several machine learning algorithms to build the models are polynomial regression, ridge regression, K-nearest neighbor regression (KNN Regression), and random forest. Comparing the performance of models based on each algorithm, the study found that KNN Regression was the most suitable model, and the result obtained from KNN regression was significant.

Environmental fundamental facilities have different odor emission characteristics depending on the type of treatment facilities. To overcome the limitations of the olfactometry method, research needs to be conducted on how to calculate the dilution factor from the individual odor concentrations. The aim of this study was to determine the air dilution factor estimated from manually measured concentration data of individual odor substances (22 specified odor species) in three environmental treatment facilities. In order to calculate the optimum algorism for each environmental fundamental facility, three types of facilities were selected, the concentration of odor substances in the exhaust gas was measured, and the contribution of the overall dilution factor was evaluated. To estimate the dilution factor, four to six algorism were induced and evaluated by correlation analysis between substance concentration and complex odor data. Dilution factors from O municipal water treatment (MWT) and Y livestock wastewater treatment (LWT) facilities showed high level of dilution factors, because concentration levels of hydrogen sulfide and methylmercaptan, which had low odor threshold concentrations, were high. In S food waste treatment (FWT) facility, the aldehyde group strongly influenced dilution the factor (dominant substance: acetaldehyde, i-valeraldhyde and methylmercaptan). In the evaluation of four to six algorism to estimate the dilution factor, the vector algorism (described in the text) was optimum for O MWT and Y LWT, while the algorism using the sum of the top-three dominant substances showed the best outcome for S FWT. In further studies, estimation of the dilution factor from simultaneously monitored data by odor sensors will be developed and integrated with the results in this study.

The effect of the change in air inflow velocity has been investigated at the opening of the malodor emission source to determine its influence on the Complex odor concentration. Both the Complex odor collection efficiency and concentrations were measured according to the change in airflow velocity. When the air inflow velocity was 0.1 m/s, it was observed that some of the generated gas streams were diffused to the outside due to low collection efficiency. In contrast, only the increased gas collection volume up to 0.5 m/s showed no substantial reduction of the Complex odor concentration, which indicates an increase in the size of the local exhaust system as well as the operation cost for the Complex odor control device. When the air inflow velocity reached 0.3 m/s, the Complex odor concentrations not only were the lowest, but the odorous gas could also be collected efficiently. The air inflow velocity at the opening of the malodor emission source was considered the key factor in determining the gas collection volume. Therefore, based on the results of this study, an optimal air inflow velocity might be suggestive to be 0.3 m/s.

The emission of odor, characterized by the combustion conditions and biomass types resulting from the use of a biomass incinerator, was analyzed. The following biomass types were considered: bark, board waste, sawdust, wood flour, wood fiver, wastewater sludge, and timber wastewater. As a study method, the physico-chemical characteristics of each biomass type were analyzed to predict the potential substances that might be emited under incomplete combustion conditions. And, the emission components of odor emission by biomass were analyzed at the laboratory level using a combustion device. In addition, the characteristics of the contaminant (odor) emission per mixture ratio of biomass were analyzed in a stoker incinerator that is in operation in an actual establishment at a scale of 300 ton/day. In the biomass emission experiment using the combustion device at the laboratory level, the major substances such as Acetic acid, Styrene, Toluene, Benzene, Dichloromethane, etc. were analyzed, and these components were determined to increase odor index. VOCs measurement in the outlet of the stoker incinerator indicated that Acetaldehyde, Ethanol, Acetonitrile, Ethyl acetate, Toluene, etc. were detected as the major substances. These were similar to the emission substances presented by the experiment that had investigated emissions by biomass type. A study on the Effect of Operational Conditions in biomass stocker incinerator on the concentration of odorous materials emitted from stack showed a close relationship between the input by biomass type and urea, temperature in the incinerator, and the tendency to emit/produce odor.

Recently, a number of researchers have produced research and reports in order to forecast more exactly air quality such as particulate matter and odor. However, such research mainly focuses on the atmospheric diffusion models that have been used for the air quality prediction in environmental engineering area. Even though it has various merits, it has some limitation in that it uses very limited spatial attributes such as geographical attributes. Thus, we propose the new approach to forecast an air quality using a deep learning based ensemble model combining temporal and spatial predictor. The temporal predictor employs the RNN LSTM and the spatial predictor is based on the geographically weighted regression model. The ensemble model also uses the RNN LSTM that combines two models with stacking structure. The ensemble model is capable of inferring the air quality of the areas without air quality monitoring station, and even forecasting future air quality. We installed the IoT sensors measuring PM2.5, PM10, H2S, NH3, VOC at the 8 stations in Jeonju in order to gather air quality data. The numerical results showed that our new model has very exact prediction capability with comparison to the real measured data. It implies that the spatial attributes should be considered to more exact air quality prediction.

In the present study, we evaluated the effect of pH modulation on concentrations of odorous compounds and pollutants in pit slurry from pig operation building. A slurry sample was taken from the pit of a pig operation building where 50 finishing pigs [(Landrase × Yorkshire) × Duroc] were kept. Three levels of pH (6, 8 and 10) were measured and adjusted daily during the incubation periods using chemical reagents of 1 N HCl or 3 N NaOH. Concentrations of odorous compounds and pollutants were analyzed from slurry incubated for 7 days. When these material concentrations were compared with the pH 8 slurry which was the pH of pit slurry, levels of short chain fatty acids, indoles and total organic carbon were reduced 7%, 68% and 2%, respectively, in the pH 6 treatment (P<0.05). Ammonium nitrogen, phenols and total nitrogen concentrations were lower by 31%, 18% and 17%, respectively, than with the pH 10 slurry (P<0.05). When the odor contribution in pH treatments was assessed according to the odor activity value, it was found to be 23% lower in the pH 6 treatment compared with pH 8. The pH modulation would affect odor emissions and microbial activity from pit slurry. Although not all odorous compounds showed the reduction effect with the same pH control, this study can be effectively used as base data when using additives for pH control.

This study was conducted to investigate the influence of moisture removal using a moisture condensation tube on the odor concentration, when sampling a malodorous substance from an odor discharge facility’s emission sites. For high-temperature and humid gas streams, the odor concentration was decreased through the use of a moisture condensation tube. The multiple odor concentration of the high-temperature and humid gas streams emitted from boiler-burning equipment decreased from a 3,000 to a 1,221 dilution factor when using one or two moisture condensation tube. This multiple odor concentration was further decreased to a 1,000 dilution factor by using two moisture condensation tubes and glass beads, and also was decreased to a 374 dilution factor by using two moisture condensation tubes and silicagel. Among the designated offensive odorous substances, ammonia, trimethylamine and acetaldehyde that have high solubility in water showed high reduction rate of their concentration. Compared to the result using a sampling tube only, the concentration was decreased by 94.8% ~ 97.7% for ammonia, by 87.5% ~ 95.9% for trimethylamine and by 100% for acetaldehyde. The findings of this study indicate that sampling using a moisture condensation tube affects the concentration of multiple odors. Therefore, it is considered that using a sampling tube only for emissions sampling enhances analytical accuracy and precision rather than using moisture condensation tube with sampling tube, even for the emissions containing moisture.

This study aims to evaluate the relationship between concentration and odor intensity using the odor sensory method for 4 types of fatty acid compounds and i-butyl alcohol. For the measurement, 18 panelists were selected based on several criteria through a panel test. Panelists chosen for their closely similar sensitivities provided more reproducible values. The estimation showed that the correlation of the concentration with odor intensity for the 5 compounds, including the fatty acid compounds and i-butyl alcohol can be reasonably expressed by the Weber-Fechner equation. Notably the standards regulation fatty acid concentrations are very strict, and the butyl acetate standards are very loose. It is suggested than the results of this study can be used as basic data for research on measures to improve the regulation standards on complex odor concentrations on site boundaries in operation, as well as the correlation between concentration and odor intensity for the designated foul odor substances, and their characteristics.

This study was carried out to estimate odors emitted from toilets in Mugunghwa trains. Two parameters, odor intensity and odor concentration, were used for odor estimation. A direct olfactory method to observe odor intensity for 67 toilets and an air dilution olfactory method to estimate odor concentration for 6 samples were performed. Results showed that odor concentrations in toilets in trains ranged from 6 OU/m3 to 30 OU/m3, and odor intensity in 67 toilets varied from 0 degree to 3.3 degree. The results suggest that odors emitted from existing toilets should be controlled because the odor intensity in 16 toilets reached a level that resulted in complaints about the odor.

양돈 사료에 발효탄수화물을 첨가하여 돼지의 슬러리에 서 악취물질의 농도를 평가하였다. VFA 분석결과, 분뇨의 SCFA 농도는 대조구, 땅콩껍질, 아몬드피 및 골든화이버 구에서 각각 1,893, 1,591, 1,433 및 1,319 ppm으로 대조구 에서 가장 높았고(p<0.05), 아몬드피와 골든파이버 구에서 가장 낮았다(p<0.05). VFA의 구성을 살펴보면 SCFA 중에 서 아세트산의 비율이 가장 높으며, 다음으로 프로피온산, 부티르산, BCFA 순으로 낮았다. BCFA의 농도는 대조구, 땅콩껍질, 아몬드피 및 골든화이버 구에서 각각 98, 92, 78 및 74 ppm으로 대조구에서 가장 높았고(p<0.05), 골든화이 버 구에서 가장 낮았다(p<0.05). VOC 분석결과, 분뇨의 페 놀류 농도는 대조구, 땅콩껍질, 아몬드피 및 골든화이버 구 에서 각각 97.3, 47.0, 54.3 및 33.3 ppm으로 골든화이버 구 에서 가장 낮았으며, 대조구에서 가장 높았다(p<0.05). 그 리고 p-크레졸 농도가 페놀류 농도의 93~96%를 차지하였 다. 인돌류 농도는 대조구, 땅콩껍질, 아몬드피 및 골든화 이버 구에서 각각 1.8, 1.3, 1.2 및 1.0 ppm으로 발효탄수화 물 처리구간에 차이가 없었으며(p>0.05), 대조구에서 가장 높았다(p<0.05). NH4 +-N의 농도는 대조구, 땅콩껍질, 아몬 드피 및 골든화이버 구에서 각각 1,395, 995, 995 및 836 ppm으로 대조구에서 가장 높았으며, 골든화이버 구에서 가 장 낮았다(p<0.05). 가축의 장내 또는 슬러리에서 발효과정 동안 미생물이 성장을 위해 필요로 하는 에너지가 제한요 소로 작용되면, 미생물은 단백질을 에너지원으로 이용하기 때문에 많은 아미노산이 분해되어 악취물질이 증가 될 수 있다. 따라서 다른 처리구에 비하여 골든화이버 구에서 VOC의 농도가 가장 낮은 것은 골든화이버의 높은 NDF 함량으로(Getachew et al., 2004) 단백질 발효보다 탄수화 물 발효가 활발하게 일어나 악취물질의 농도가 낮았다고 판단된다.

본 연구는 양돈 슬러리의 악취물질 감소에 효과가 있는 것으로 확인된 물질의 효능을 비교분석하기 위하여 수행되 었다. 페놀류 농도는 고추냉이와 아몬드피 구에서 낮았고, 인돌류 농도는 아몬드피 구에서 가장 낮았다(p<0.05). 따라 서 슬러리에 아몬드피를 첨가하면 VOC 농도가 감소되었 다. SCFA 농도는 팽이버섯폐배지와 아몬드피 구에서 높았 고, BCFA 농도는 대조구에 비해 다른 모든 처리구에서 낮 았다(p<0.05). 또한 슬러리의 pH는 팽이버섯폐배지와 아몬 드피 구에서 낮았다(p<0.05). 따라서 팽이버섯폐배지 또는 아몬드피를 슬러리에 첨가하면 SCFA 농도는 증가되고 BCFA 농도는 감소되는 것으로 나타났다.

도시지역 합류식 하수배제 설비인 우수받이 및 하수관거, 정화조 등에는 유기성 고형 물이 퇴적되기 쉬우며, 유기성 퇴적물이 부패되는 과정에서 고농도의 황계열 악취물질이 발생한다. 본 연구에서는 전기산화방식을 이용하여 유기성 퇴적물 내에 용존된 악취물질 및 전구물질을 저감시켜, 하수관거에서 기상으로 배출되는 악취 문제를 해결하고자 하였다. 실험실 규모의 밀폐된 회분식 반응기에 하수슬러지(COD 기준 8,000 ~ 28,000 mg·L-1)를 투입하고, 발생되는 악취물질 농도와 악취발생특성을 조사하였다. 여기에 전기산화시스템 을 적용하여 황계열 악취물질과 전체 유기물의 산화 및 분해실험을 진행하였다. 전기산 화 실험을 진행한 결과, 밀폐된 반응기의 기상에서 450 ppm의 고농도로 발생한 황화수 소가 반응 30분 이내에 검출한계 이하까지 제거되었으며, 메틸머켑탄과 디메틸설파이드 는 85% 이상 제거되었다. 투입된 전기에너지당 황계열 악취물질의 제거율은 최대 0.33 mg-S·kJ-1로 나타났다. 또한 1시간의 반응기간 동안 회분식 반응기 내에서 황계열 악취물 질 뿐만 아니라 고농도 퇴적물에 함유된 전체 유기물 농도가 56% 감소하여, 전기산화시 스템이 악취를 유발하는 유기성 전구물질을 동시에 저감하는 효과를 나타내었다. 결과적 으로 최소한의 전기에너지를 이용하여 하수관거 퇴적 유기물에 의한 악취문제를 해결할 수 있을 것으로 기대된다

우리나라에서 악취 규제는 배출원의 부지경계선과 배출구에서 농도 규제치를 사용한다. 그러므로 수용체에서 정확한 체감악취의 유무를 쉽게 판단하기는 곤란하다. 비록 개개인의 악취에 대한 응답을 결정하는 변수는 다양하고 응답 종류도 광범위하게 나타나지만, 일반적으로 악취에 대한 규제는 다양한 변수를 고려하여 구성되며, 이들 변수에는 악취 발생빈도, 강도, 기간, 불쾌도, 지역 변수 등이 있다. 본 연구에서는 매사추세츠(미국), 뉴질랜드, 덴마크, 네덜란드, 호주 서부, 타이완 등 6개 지역의 악취 규제를 사용하여 소각장 주변에서 악취 영향 거리를 비교하였다. 악취 영향 거리를 평가하기 위하여 이들 6개 지역 규제는 악취 농도와 허용 빈도를 고려하고 있다. 연구 결과에 의하면 악취에 의한 영향 거리는 0.5~1.4 km의 범위로 나타났다. 악취 농도를 고정하고 허용 빈도를 변경하는 경우 허용 빈도가 높을수록 영향 거리는 크게 나타났다. 허용 빈도를 고정하고 농도를 변화시키는 경우 농도가 높으면 영향거리가 줄어들었다. 결론적으로 악취 영향 범위는 악취 농도뿐 아니라 허용 빈도에 따라 변화하였다.

The correlations among odor intensity, offensive substance concentration, and dilution factor were reviewed for the 12 designated offensive odor substances in this study. It is to propose new regulatory odor standards based on relationships between odor intensity and offensive substance concentration, as well as odor intensity and dilution factor at the site boundary which were obtained from the comprehensive reviews of the adequacy of current regulation standards. Changes in intensity were found to be necessary to reflect exponential changes in concentrations and dilution factors. The change of substance concentrations with respect to the dilution factor was found to be a relatively linear relationship. The thorough evaluations pf relationships among odor intensity, offensive substance concentration, and dilution factor led to the conclusion that the current regulatory standards were inadequate and the modification was necessary to reflect the new understandings. The new regulatory substance standards based on correlations with odor intensity for the 12 compounds were proposed. The proposed ammonia concentrations for the regulatory standard in the semi-industrial and industrial area were 15 ppm and 28 ppm, respectively. These are approximately 15 times higher than those of the current standards. For dimethyl sulfide, dimethyl disulfide, and isovaleraldehyde, the higher concentrations than those of current standards were also pro posed. The proposed regulatory standards of dilution factor in semi-industrial and industrial area were 25 and 50, respectively. It is found that proposed quantitative relationships among the odor intensity, the offensive substance concentration, and the dilution factor in this study turned out to be more adequate to Korean than the current ones.

This field study was performed to investigate indoor concentrations of 22 odorous compounds, which are regulated by the domestic act, emitted from poultry buildings through on-site visit per month from July, 2011 to June, 2012. Of 22 odorous compounds, the highest concentration was found in ammonia with ppm unit, followed by hydrogen sulfide, methyl ethyl ketone, propionic acid and butylic acid with ppb unit of approximate hundred level. The other odorous compounds were detected below ppb unit of approximate ten level. A remarkable finding is that there is no poultry building which showed the airborne levels of five aldehyde- based odorous compounds (acetaldehyde, propionaldehyde, butyraldehyde, n-valeraldehyde and i-valeraldehyde). Generally there was no consistent concentration distribution of odorous compounds between poultry building applied with forced ventilation and poultry building applied with natural ventilation. It was found, however, that there was considerable concentration difference among odorous compounds. In temporal distribution of odorous compounds, their concentrations in summer season (June to August) when ventilation rate in poultry building decreased relatively were generally higher than those in winter season (December to February) when ventilation rate in poultry building is relatively high. The seasons of spring (March to May) and autumn (September to November) showed middle levels of odorous compounds between summer and winter. The limit of this study is that unexpected conditions such as clearance of poultry building, poultry shipment and disorder of air pump were not controlled intentionally on the on-site investigation days.

An objectives of this study is to investigate indoor concentrations of 22 odorous compounds, which are regulated by the domestic act, emitted from pig buildings through on-site visit per month from July, 2011 to June, 2012. Of 22 odorous compounds, the highest concentration was found in ammonia with ppm unit, followed by hydrogen sulfide, methyl ethyl ketone, propionic acid and butylic acid with ppb unit of approximate hundred level. The other odorous compounds were detected below ppb unit of approximate ten level. A remarkable finding is that there is no pig building which showed the airborne levels of five aldehyde-based odorous compounds (acetaldehyde, propionaldehyde, butyraldehyde, n-valeraldehyde and i-valeraldehyde). In general, indoor concentrations of odorous compounds in pig buildings were higher in scraper type than slurry type based on pig manure collection system and higher in enclosed type than winch-curtain type based on ventilation mode, respectively. In temporal distribution of odorous compounds, their concentrations in summer season (June to August) when ventilation rate in pig building decreased relatively were generally higher than those in winter season (December to February) when ventilation rate in pig building is relatively high. The seasons of spring (March to May) and autumn (September to November) showed middle levels of odorous compounds between summer and winter.

This study aims to evaluate the relationship with the concentration and odor intensity using the odor sensory method for 5 types of aldehyde compounds and styrene. For the measurement, 13 panelists were selected by several criteria through a panel test. The estimation showed that the correlation of the concentration with odor intensity for the 12 compounds including of the sulfur compounds, ammonia, and trimethylamine can be reasonably expressed by the equation I = Aㆍlog C + B (I : odor Intensity, C : material concentration, A : material constant, B : constant). The equations show the sensivities of intensity change for the change of concentration. According to the increase of concentration the odor intensities for acetaldehyde and iso-valeraldehyde increase larger than for the other aldehydes. Regulation standards of 12 species of odor substance concentraton and odor intensity by using the correlation equation was reviewed for adequacy. It was evaluated that the regulation standards on site boundary in operation are too low for NH₃, DMDS, and iso-valeraldehyde and too high for TMA. The result of this study is suggested to be used as a base data for research on measures to improve the regulation standards for complex odor concentration on site boundary in operation.

There are many pollutants emitted into the air. Some of these pollutants have a malodor. Unlike other pollutants, people are able to detect and feel discomfort when this type of pollutant becomes high peak concentration instantaneously. In this sense, the peak concentration has an important meaning in the odor management and modeling. In previous odor modeling, the peak concentration was calculated by correcting the one-hour average concentration using the correlation equation. This study was carried out to find appropriate method to predict the peak concentration using meteorological input data of high time resolution in the odor modeling. It show that the peak concentration could be directly calculated from the dispersion modeling without using the correction equation when fine time scales such as 1 min or less time intervals are used as the meteorological input.