Review of Federally Sponsored Research on Diesel Exhaust Odors

The information presented in this paper is directed to persons concerned with control of exhaust odors from diesel-engine-powered vehicles. This paper summarizes projects sponsored by the Environmental Protection Agency (EPA) over the past years in the field of diesel-exhaust odor. These investigations have concentrated on developing measurement methods for quantifying different odor levels, evaluating various odor control methods, and evaluating public opinions of such odors.

A human panel method using odor reference standards has been found suitable to measure these odor levels. In addition to this technique, chemical characterization work has been sponsored under a project jointly sponsored by the Coordinating Research Council and the EPA to isolate and identify those species responsible for the odor.

Knowledge of these odorous compounds and the techniques necessary to isolate them should lead to development of a chemical method to measure this type of odor, in place of human panelists. Such basic information would also lead to developing control techniques to minimize this odor.

Several control techniques were evaluated for diesel exhaust odor. To date, the most effective method is an improved needle injector for use in the Detroit Diesel type E 6V-71 engine commonly used in buses.

Finally, public reaction to diesel-engine-exhaust odor has been measured. It has been found that a systematic relationship exists between increasing public objections and increasing diesel odor intensity.     

Community Response to Environmental Noise

A portable 1-butanol olfactometer was developed for quantifying odors in ambient air. Panelists compare the intensity of ambient odors with the intensity of discrete levels of 1-butanol provided by the olfactometer. Range of delivered 1-butanol concentrations Is 0 to 80 ppm in air at a flow rate of 15 L/min. Laboratory tests were performed to ascertain overall precision, consistency of panelist responses, uniqueness of each odor step, variability between two Identical olfactometers, and effect of delivery method. For 855 pairs of matched odor Intensities, the ratio of measured butanol concentration to set concentration averaged 0.984 or —0.023 scale steps (where the scale steps differ In concentration by factors of two). In field experiments the equivalent ambient odor Intensities determined by odor panels using the butanol olfactometer ranged from 1.5 ppm to 64 ppm of 1-butanol vapor In air. The precision of ambient odor measurements was within one-half scale step on the 1-butanol olfactometer, sufficient for most odor investigation and abatement research applications.     

Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry

Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions.     

城市污水厂主要处理单元恶臭及挥发性有机物的逸散

在污水处理厂的主要处理工艺段设置采样点,采用在线监测仪,检测空气中恶臭及挥发性有机物(VOCs)的浓度,明确主要恶臭物质和排放源,研究恶臭及VOC在不同季节的逸散特征。结果表明,恶臭和VOC的排放主要集中在进水区,浓度与进水水质相关。粗格栅间是主要的恶臭源,其恶臭、TVOC、硫化物和胺类的浓度分别为3 458.54~5 028.03 OU、120~221 mg/m3、253~464 mg/m3和15~36 mg/m3,占各个监测点浓度总量的80.6%、93%、90%和89%。主要的恶臭物质为硫化氢和氨,其浓度对应的臭气强度超过4级。恶臭与VOC的排放呈现季节变化,夏季的浓度明显高于冬季。相关性分析显示,恶臭浓度与TVOC、硫化物、胺类浓度具有明显的相关性。     

Treatment of odor by a seashell biofilter at a wastewater treatment plant

Biofilters are becoming an increasingly popular treatment device for odors and other volatiles found at wastewater treatment plants. A seashell media based biofilter was installed in April 2011 at Lake Wildwood Wastewater Treatment Plant located in Penn Valley, California. It was sampled seasonally to examine its ability to treat odorous compounds found in the air above the anaerobic equalization basin at the front end of the plant and to examine the properties of the biofilter and its recirculating water system. The odor profile method sensory panels found mainly sulfide odors (rotten eggs and rotten vegetable) and some fecal odors. This proved to be a useful guidance tool for selecting the required types of chemical sampling. The predominant odorous compounds found were hydrogen sulfide, methyl mercaptan and dimethyl sulfide. These compounds were effectively removed by the biofilter at greater than 99% removal efficiency therein reducing the chemical concentrations to below their odor thresholds. Aldehydes found in the biofilter were below odor thresholds but served as indicators of biological activity. Gas chromatography with mass spectrometry and gas chromatography with sensory detection showed the presence of dimethyl disulfide and dimethyl trisulfide as well, but barely above their respective odor thresholds. The neutrality of the pH of the recirculating water was variable depending on conditions in the biofilter, but a local neutral pH was found in the shells themselves. Other measurements of the recirculating water indicated that the majority of the bio-activity takes place in the first stage of the biofilter. All measurements performed suggest that this seashell biofilter is successful at removing odors found at Lake Wildwood. This study is an initial examination into the mechanism of the removal of odorous compounds in a seashell biofilter.

Implications:?This paper presents a thorough examination of a seashell media biofilter, a sustainable treatment technology used to remove reduced sulfide compounds. The durable performance of the seashell biofilter ensures that odors will be adequately controlled, preventing odor nuisance to surrounding residences, which is an emerging problem faced by waste management facilities. The odor profile method technique used in this study can be applied in many situations by waste management facilities and regulatory air management organizations for source tracking in relation to prevention and management of odor complaints, respectively.     

Nature of Odor Components in Diesel Exhaust

Offensive exhaust odors are characteristic of diesel engines. One problem in control and reduction of odor is lack of understanding of odorant sources and mode of formation. The solution of this problem depends on identification of the odorants so that study of their formation and control can be undertaken. A human panel performed odor assessments in studying raw and modified diesel exhaust and synthetic blends representing portions of diesel exhaust. Their assessments were used in determining odorant identity and quantitative contribution to exhaust odor. Low molecular weight aldehydes appear to contribute little to diesel odors. The sulfur and nitrogen oxides have been examined as odorants but of these apparently only nitrogen dioxide is a potential odor contributor.     

红升水库藻源性嗅味问题解析

2021年红升水库出现了一次严重的饮用水嗅味问题,结合同期的水样采集和分析,对嗅味特征、嗅味物质和藻类等主要参数进行了系统调查。采用嗅味层次分析法(FPA)对嗅味类型和强度进行了评估,并参考主成分(PCA)和相关性分析结果对藻类和嗅味物质进行关联。在藻类物种中,绿藻和硅藻最为丰富,占比分别为43.6%和29.1%。其中,星杆藻属密度最大(5.58×10⁵ 细胞·mL⁻¹)。检测到土臭素(GSM)、2-甲基异莰醇(2-MIB)、庚醛、壬醛、癸醛、2,4-庚二烯醛、2,6-壬二烯醛、2,4-癸二烯醛等8种嗅味物质。根据FPA分析,红升水库饮用水嗅味为强烈的鱼腥味伴随轻微的土臭味、霉味,2种嗅味强度最高值均出现在水库西南侧的荷花池附近。PCA分析结果表明,饱和醛(庚醛、壬醛和癸醛)是产生鱼腥味的主要嗅味物质,但不饱和醛的影响仍不可忽略。庚醛和2,4-癸二烯醛可能与硅藻中星杆藻属和小环藻属的生长代谢有关,而壬醛、2,4-庚二烯醛和2,6-壬二烯醛则可能是绿藻中衣藻属和实球藻属的代谢产物。研究结果表明,蓝藻的暴发是红升水库出现土臭味、霉味的主要原因,而更为严重的鱼腥味问题则是由水中的螺旋藻属、类颤藻属、星杆藻属、小环藻属、衣藻属和实球藻属的大量繁殖引起的。     

Odor dispersion modeling with CALPUFF: Case study of a waste and residue treatment incineration and utilization plant in Kocaeli,Turkey

This study addresses the odor problem at a waste and residue treatment incineration and utilization plant located within the borders the Alikahya district of the Kocaeli province in Turkey. In the first stage of the study, odor measurements were made at designated sampling points, while in the second stage, odor concentrations were determined at the receptor points through dispersion modelling using a USEPA (United States Environmental Protection Agency) certified long-range (>50 km) CALPUFF lagrangian puff model. In the final stage, an analysis of the predicted and observed values was carried out using such statistical methods as geometric mean bias (MG), geometric variance (VG) and fractions of predictions within a factor of two observations (FAC2).

During the modelling study, the highest one-hour concentration level was found to be 1868.10 OU (Odor Units), and the 24-hour concentration level was found to be 1316 OU, representing a decrease of approximately 30 percent. According to the measurement made, the maximum concentration value was 2455 OU. Odor measurements were carried out at 13 points within the area in order to assess the prediction results. When the results were assessed using the MG, VG and FAC2 statistical methods, it was observed that an acceptable model performance was not achieved for the whole sampling point. When the reason for this was investigated, it was concluded that the observed values were lower than the predicted values due to the fact on the measurement days, the odor was dispersed by wind. It was further concluded that the observed values were higher than the predicted values as a result of odors emitted by other plants in the area. When the measurements in residential areas were examined to identify the effect of the odors, it was determined that although the primary density of settlement is to the southwest of the plant, it was not this area that was affected most, but rather the area to the northeast, where there is a lower settlement density.     

餐厨垃圾两相厌氧发酵产甲烷相恶臭排放规律

为了研究餐厨垃圾两相厌氧发酵产甲烷相恶臭排放规律,在中温（35℃）条件下,以餐厨垃圾为发酵底物进行中试规模的两相连续式厌氧发酵试验,并对一个周期内不同时间段产甲烷相产生的气体进行采样,分析其臭气浓度和物质浓度,结合各组分的阈稀释倍数,筛选出主要的恶臭污染物。结果表明,在发酵系统稳定运行阶段,产甲烷相产生的臭气浓度较大,都在23万以上;产甲烷相产生的恶臭物质主要包括硫化物、萜烯类、含氧类和芳烃类四类化合物,其中质量浓度最高的恶臭物质是硫化氢,超过了150 mg/m3;产甲烷相的主要致臭物质是硫化物,其中贡献最大的是硫化氢,其阈稀释倍数都在26万以上,其次为乙硫醇﹥甲硫醇﹥乙硫醚,这3种物质的阈稀释倍数都在4 000以上;除了这4种硫化物,丁醛对恶臭的贡献也比较大,其阈稀释倍数也在4 000以上。     

Sensory Measurement of Ambient Traffic Odors

Laboratory determinations of ambient traffic odors were conducted in the streets of Stockholm. The measurements were made with a sensory method based on signal detection theory. The occurrence of odors was expressed by an index of detectability (d′) which was compared to the ambient carbon monoxide concentration and the rhythm of the traffic. The results showed that the detection technique employed could well be adjusted to field conditions by use of a mobile odor laboratory. Also, the odor index (d′) was correlated with other parameters in the trafficked environment in the expected way. The odorous emissions are likely to be diluted quickly as distance from the street increases. However, the relevance of the index of detectability as a measure of dose and response needs to be studied further.     

Filters and Filter Media for the Cement Industry

To correlate the odor strength of natural gas with its sulfur analysis, the recognition odor thresholds of 18 sulfur compounds were determined using an untrained panel of 35 peopie. For each test a series of odor concentrations graduated in increments of 10^0.2 was presented to the panel in random order over a range of concentrations above and below the olfactory thresholds of all panelists. Each odor was tested on at least three different days. Desired odor concentrations were produced by dynamic blending of gaseous mixtures of the odorous compounds with air. All testing was done out-of-doors during clement weather when no ambient odors were apparent. The range of olfactory response was found to be much greater for certain compounds than for others. Branching of the hydro-carbon chain increased odor strength. Certain compounds appeared to evoke anomalous responses.     

Measurement of Ambient Odors Using Dynamic Forced-Choice Triangle Olfactometer

Certain odor control regulations specify use of the Scentometer for ambient odor measurement. This evaluation is usually performed by a single individual who is surrounded by the odorous environment to be measured. A method is desired where an ambient odor sample can be evaluated by an adequate size panel in an odor-free atmosphere. A dynamic forced-choice triangle olfactometer was designed and constructed to measure ambient odors. Teflon bags of 18 liter capacity collect a sample within 2-3 minutes which includes pre-flushing the bag. The sample is evaluated by a dynamic olfactometer equipped with 5 dilution levels (81×, 27×, 9×, 3× and undiluted sample). Three sniffing ports are provided at each dilution level to present dynamically one diluted odor stimulus and two odor-free air blanks. Each panelist is required to indicate which port contains the odor. Evaluation of one sample is routinely completed by a panel of 9 within less than 15 minutes. The odor threshold value (ED₅₀) for the panel is calculated by use of a simple table derived statistically. No significant loss of odor was observed in sampling and in storage of rendering odors up to 48 hours. Bags were reusable after flushing with odor-free air. Reproducibility of log ED₅₀ values by the same panel was within a σ = 0.10 log₁₀. Agreement in evaluating duplicate field samples by two different panels was within the same limits. Under controlled laboratory conditions, a Scentometer reading of D/T = 2 was equivalent to an ED₅₀ = 4.8; and D/T = 7 was equal to ED₅₀ = 9.5.     

Evaluating peats for their capacities to remove odorous compounds from liquid swine manure using headspace “solid‐phase microextraction”

Abstract

This paper reports on research designed to investigate the capacities of different highly characterized peats to remove odorous compounds from liquid swine manure (LSM). Peat types representing a wide range of properties were tested in order to establish which chemical and physical properties might be most indicative of their capacities to remediate odors produced by LSM. Eight percent slurries (of peat/LSM) were measured for odor changes after 24 hours using odor panel and GC/MS‐Solid‐phase microextraction (GC/MS‐SPME) analysis.

The GC/MS‐SPME and odor panel results indicated that, although all peats tested in this study were found to be effective at removing odor‐causing compounds found in LSM, some peats tended to work better than others. Overall, the peats that were the most effective at removing odor‐causing compounds tended to have lower bulk densities, ash contents, fulvic acids contents, and guaiacyl lignins contents,and higher water holding capacities, hydraulic conductivities, “total other lignins”; contents, hydrogen contents, carbon contents, and total cellulose contents.

GC/MS‐SPME analysis was found to be a reasonably inexpensive and efficient way of conducting this type of research. It allows one to identify a large number of the odor‐causing compounds found in LSM, and more importantly, to detect with some precision specific differences in the amounts of these compounds between peat types.     

Preventive control of odor emissions through manipulation of operational parameters during the active phase of composting

Better understanding of the effects of key operational parameters or environmental factors on odor emission is of critical importance for minimizing the generation of composting odors. A series of laboratory experiments was conducted to examine the effects of various operating conditions on odor emissions. The results revealed that airflow rates that were too high or too low could result in higher total odor emissions. An optimal flowrate for odor control would be approximately 0.6 L/min.kg dry matter with intermittent aeration and a duty cycle of 33%. Temperature setpoint at 60°C appeared to be a turning point for odor emission. Below this point, odor emissions increased with increasing temperature setpoint; conversely, odor emissions decreased with increasing temperature setpoint above this point. With regard to the composting material properties, odor emissions were greatly affected by the initial moisture content of feedstock. Both peak odor concentration and emission rate generally increased with higher initial moisture content. Odor emission was significant only at moisture levels higher than 65%. An initial moisture level below 45% is not recommended due to concern with the resulting lower degree of biodegradation. Biodegradable volatile solids content (BVS) of feedstock had pronounced effect on odor emissions. Peak odor concentration and emission rate increased dramatically as BVS increased from 45% to 65%, thus, total odor emission increased exponentially with BVS.     

国内成功运营的餐厨垃圾处理厂臭气排放特征研究

选择目前国内成功运营的餐厨垃圾资源化处理厂为采样点,采用气相色谱．质谱联用（GC／MS）技术对该厂的主要工段,如卸料室、破碎室、湿热反应器出气口、好氧发酵仓、厌氧发酵区以及厂界的臭气进行了定性和定量的分析。结果表明,6个采样点共检测出包括芳香烃、硫化物、卤代物、烯烃、烷烃、醇、醛、酮和酯在内的9类66种物质,各采样点臭气总浓度分别为：11．738、18．390、30．917、25．097、4．737和2．635mg／m3。其中湿热反应器出气口处恶臭气体浓度最高,其芳香烃、硫化物、卤代物、烯烃、烷烃、酮及酯类物质均高于其他检测点,需对该工段进行重点监测和控制。恶臭排放特征分析表明,各点的H2S浓度均超过嗅觉阈值,除厂界外甲硫醇和二甲二硫检测值均超过嗅觉阈值。     

Industrial odor sources and air pollutant concentrations in Globeville,a Denver,Colorado neighborhood

An odor of unknown origin described as a “tar” or “asphalt” smell has become unbearable for many of Globeville, CO, residents over the past few years. Residents report during odor events burning eyes and throat, headaches, skin irritation, and problems sleeping. This study was undertaken to identify the potential sources of the odor and the concentrations of air pollutants making up the odor by conducting meteorological correlations and sampling for a panel of volatile organic compounds (VOCs), sulfur gases, and polycyclic aromatic hydrocarbons (PAHs) in the neighborhood and near suspected sources. Wind speed and direction data collected every 1 min in the neighborhood indicate that when the odor is noticed, the community is directly downwind of a wood preservation facility and an asphalt roofing facility. Air samples collected during high-intensity odor events have shown concentrations of methylene chloride, hexane, toluene, naphthalene, dibenz[a,h]anthracene, benzo[g,h,i]perylene, and indeno[1,2,3-cd]pyrene, each at least two times higher than background concentrations. Naphthalene and the other PAHs are known pollutants emitted from wood treatment processes, and are known to have a coal tar odor. Naphthalene was present in a sample collected directly adjacent to the Koppers facility and was not present in any background samples. Single-compound odor and health thresholds, however, were never surpassed. Given the technical and regulatory challenges of sampling odors and controlling emissions, it is recommended that Globeville residents and neighboring industry pursue a “good neighbor policy” to solve the odor issue. Specific offending industrial processes could be identified for which there exist cost-effective control technologies that would reduce exposure to odors and air toxics in Globeville.

Implications: Meteorological correlations and samples of volatile organic compounds (VOCs), sulfur gases, and polycyclic aromatic hydrocarbons (PAHs) in the Globeville, CO, neighborhood and near suspected sources during odor events indicate potential industrial sources of a transient and noxious odor. Legislative approaches have proven unfruitful and no health or odor thresholds were typically violated. New approaches are warranted to address odor mixture effects in neighborhoods near industrial facilities.     

国内成功运营的餐厨垃圾处理厂臭气排放特征研究简

选择目前国内成功运营的餐厨垃圾资源化处理厂为采样点,采用气相色谱-质谱联用（GC/MS）技术对该厂的主要工段,如卸料室、破碎室、湿热反应器出气口、好氧发酵仓、厌氧发酵区以及厂界的臭气进行了定性和定量的分析。结果表明,6个采样点共检测出包括芳香烃、硫化物、卤代物、烯烃、烷烃、醇、醛、酮和酯在内的9类66种物质,各采样点臭气总浓度分别为：11.738、18.390、30.917、25.097、4.737和2.635 mg/m³。其中湿热反应器出气口处恶臭气体浓度最高,其芳香烃、硫化物、卤代物、烯烃、烷烃、酮及酯类物质均高于其他检测点,需对该工段进行重点监测和控制。恶臭排放特征分析表明,各点的H₂S浓度均超过嗅觉阈值,除厂界外甲硫醇和二甲二硫检测值均超过嗅觉阈值。     

Consultant Guide/1986

ABSTRACT

To obtain annual odor emission profiles from intensive swine operations, odor concentrations and emission rates were measured monthly from swine nursery, farrowing, and gestation rooms for a year. Large annual variations in odor concentrations and emissions were found in all the rooms and the impact of the seasonal factor (month) was significant (P < 0.05). Odor concentration was low in summer when ventilation rate was high but high in winter when ventilation rate was low, ranging from 362 (farrowing room in July) to 8934 (nursery room in December) olfactory unit (OU) m^?3. This indicates that the air quality regarding odor was significantly better in summer than that in winter. Odor emission rate did not show obvious seasonal pattern as odor concentration did, ranging from 2 (gestation room in November) to 90 (nursery room in April) OU m^?2 sec^?1; this explains why the odor complaints for swine barns have occurred all year round. The annual geometric mean odor concentration and emission rate of the nursery room was significantly higher than the other rooms (P < 0.05). In order to obtain the representative annual emission rate, measurements have to be taken at least monthly, and then the geometric mean of the monthly values will represent the annual emission rate. Incorporating odor control technologies in the nursery area will be the most efficient in reducing odor emission from the farm considering its emission rate was 2 to 3 times of the other areas. The swine grower-finisher area was the major odor source contributing 53% of odor emission of the farm and should also be targeted for odor control. Relatively positive correlations between odor concentration and both H₂S and CO₂ concentrations (R ² = 0.58) means that high level of these two gases might likely indicate high odor concentration in swine barns.

IMPLICATIONS The emissions of air pollutants including odors, greenhouse gases, and toxic gases have become a major environmental issue facing animal farms in the U.S.A. and Canada. To ensure the air quality in the vicinity of intensive livestock farms, air dispersion models have been used to determine setback distances between livestock facilities and neighboring residences based on certain air quality requirement on odor and gases. Due to the limited odor emission data available, none of the existing models can take account of seasonal variations of odor emissions, which may result in great uncertainties in setback distance calculations. Therefore, the obtained seasonal odor and gas emission rates by this study can be used by the government regulatory organizations and researchers in air dispersion modeling to get improved calculation of setback distances.