Bacteria additives to the changes in gaseous mass transfer from stored swine manure

Abstract

A bacteria additives treatment experiment in assessing the changes in gaseous mass transfer from stored swine manure is presented. The experiment is tested for ammonia, methane, hydrogen sulfide, and carbon dioxide emission data sampled from pilot swine manure columns and analyzed by GC/MS. The result shows that bacteria additives slightly reduce the methane and carbon dioxide releases, while the same additives do not show any effect on the reduction of ammonia. The hydrogen sulfide contents of stored swine manure continued to be low. Gas concentrations emitted from treated and untreated stored swine manure were: 3.76 and 2.2 ppm for methane, 0.35 and 0.11 ppm for ammonia, and 1000 and 470 ppm for carbon dioxide, respectively. A simple model to estimate gas emission rates is also developed from the viewpoint of two‐film resistance theory. The average emission rates calculated from the model for methane, ammonia, and carbon dioxide are respectively: 0.01, 0.0005, and 13.98 g/min from untreated stored manure; while 0.07, 0.096, and 0.55 g/min from treated manure. The emission model also indicates that for most gaseous pollutants of environmental concern, liquid phase transfer coefficient controls the rate of volatile compounds emitted from stored swine manure and gas phase transfer coefficient has insignificant effect in the calculation of overall mass transfer coefficient.     

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.     

Controlled Exposures of Volunteers to Respirable Carbon and Sulf uric Acid Aerosols

Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, we exposed 15 healthy and 15 asthmatic volunteers in a controlled- environment chamber (21°C, 50 percent relative humidity) to four test atmospheres: (i) clean air; (ii) 0.5-μm H2SO4 aerosol at =100 μg/m³, generated from water solution; (iii) 0,5-μm carbon aerosol at =250 μg/m³, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (iv) carbon as in (iii) plus =100 μg/m³ of ultrafine H2SO4 aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (iv) became attached to carbon particle surfaces, and that most particles remained in the sub-μm size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation =50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at endexposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H₂SO₄ or carbon, separate or interactive, on health measures. Group data showed no more than small equivocal effects of any exposure on any health measure. One individual's responses were consistent with a clinically significant excess airway constriction from H₂SO₄ plus carbon, and 2-3 others showed slight excess responses to the combined pollutants, but all these observations might have reflected chance variations. We conclude that coexisting carbon aerosol did not increase respiratory irritancy of H₂SO₄, in most healthy and asthmatic subjects exposed for 1 hr under simulated "worst-case" ambient conditions.     

动态法测试空气净化器甲醛去除性能的研究

通过动态法测试水吸收型空气净化器A和活性炭过滤吸附型净化器B对甲醛的去除性能,探索更为合理的方法以评价空气净化器对气态污染物的去除性能.对净化器A去除甲醛的短期测试结果表明,净化器对甲醛浓度为0.3、0.5、0.8和1 mg/m3的连续空气流均有明显的净化效果,对甲醛的去除速率在0.91～2.78 mg/h之间.对净化...     

Treatment of 1,3-Butadiene in an Air Stream by a Biotrickling Filter and a Biofilter

ABSTRACT

This paper presents results obtained from a performance study on the biotreatment of 1,3-butadiene in an air stream using a reactor that consisted of a two-stage, in-series biotrickling filter connected with a three-stage, in-series biofilter. Slags and pig manure-based media were used as packing materials for the biotrickling filter and the biofilter, respectively. Experimental results indicated that, for the biotrickling filter portion, the butadiene elimination capacities were below 5 g/m³/hr for loadings of less than 25 g/m³/hr, and the butadiene removal efficiency was only around 17%. For the biofilter portion, the elimination capacities ranged from 10 to 107 g/m³/hr for loadings of less than 148 g/m³/hr. The average butadiene removal efficiency was 75–84% for superficial gas velocities of 53–142 m/hr and a loading range of 10–120 g/m³/hr. The elimination capacity approached a maximum of 108 g/m³/hr for a loading of 150 g/m³/hr. The elimination rates of butadiene in both the biotrickling filter and biofilter were mass-transfer controlled for influent butadiene concentrations below about 600 ppm for superficial gas velocities of 29–142 m/hr. The elimination capacity was significantly higher in the biofilter than in the biotrickling filter. This discrepancy may be attributed to the higher mass-transfer coefficient and gas-solid interfacial area offered for transferring the gaseous butadiene in the biofilter.     

In Situ Determination of the Rate of Unassisted Degradation of Saturated-Zone Hydrocarbon Contamination

Abstract

A method to measure the in situ degradation rate of dissolved hydrocarbon contamination has been developed and applied at two locations at a field site. The method uses the rates of downward diffusion of oxygen and upward diffusion of carbon dioxide through the unsaturated zone, as calculated from vertical soil-gas concentration gradients, combined with stoichiometry to obtain two degradation rates in hydrocarbon mass per water table surface area per time. Values of 0.385 gram per m² per day and 0.52 gram per m² per day (based upon oxygen data) and 0.056 gram per m² per day and 0.12 gram per m² per day (based upon carbon dioxide data) were calculated at a field site with dissolved fuel contamination. This result of lower values from ground-air carbon dioxide concentrations is consistent with a significant fraction of the carbon dioxide produced being lost to the aqueous phase. Based upon a single-stage equilibrium phase-transfer model, gas/water volume ratios of 0.02 and 0.2 for the capillary fringe were calculated. Groundwater carbon dioxide fugacities and soil-gas carbon dioxide concentrations were used at the two locations and a third to determine whether the source of elevated soil carbon dioxide concentrations were unsaturated-zone hydrocarbon degradation or a saturated-zone process. This technique has potential applicability in setting risk-based remedial criteria and in allowing inclusion of the contribution of in situ degradation in remedial design. This can result in major remedial cost savings.     

Studies on a New Method of Simultaneously Removing Sulfur Dioxide and Oxides of Nitrogen from Combustion Gases

Simultaneous reduction of SO₂ and NO by catalyzed reaction with carbon monoxide at space rates approaching 10⁴ vol/vol/hr has been shown. The reaction of sulfur dioxide with carbon monoxide results in the formation of carbon dioxide and elemental sulfur. Nitric oxide reacts with carbon monoxide to form carbon dioxide and molecular nitrogen. Metals supported on alumina appear to be the preferred catalysts. Among the effective metals are copper, silver, and palladium. A side reaction of carbon monoxide with elemental sulfur to form carbonyl sulfide requires that the initial amount of carbon monoxide be stoichio-metric for the amount of sulfur dioxide plus nitric oxide present. A furnace employing this method would have to be operated at low excess air, near stoichiometric fuel/air, or possibly slightly on the rich side.     

Short-Term Effects of Gaseous Pollutants on Cause-Specific Mortality in Wuhan,China

Abstract

In Asia, limited studies have been published on the association between daily mortality and gaseous pollutants of nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂). Our previous studies in Wuhan, China, demonstrated long-term air pollution effects. However, no study has been conducted to determine mortality effects of air pollution in this region. This study was to determine the acute mortality effects of the gaseous pollutants in Wuhan, a city with 7.5 million permanent residents during the period from 2000 to 2004. There are approximately 4.5 million residents in Wuhan who live in the city’s core area of 201 km², where air pollution levels are highest, and pollution ranges are wider than the majority of the cities in the published literature. We used the generalized additive model to analyze pollution, mortality, and covariate data. We found consistent NO₂effects on mortality with the strongest effects on the same day. Every 10-μg/m³increase in NO₂daily concentration on the same day was associated with an increase in nonaccidental (1.43%; 95% confidence interval [CI]: 0.87–1.99%), cardiovascular (1.65%; 95% CI: 0.87–2.45%), stroke (1.49%; 95% CI: 0.56–2.43%), cardiac (1.77%; 95% CI: 0.44–3.12%), respiratory (2.23%; 95% CI: 0.52–3.96%), and cardiopulmonary mortality (1.60%; 95% CI: 0.85– 2.35%). These effects were stronger among the elderly than among the young. Formal examination of exposure-response curves suggests no-threshold linear relationships between daily mortality and NO₂, where the NO₂concentrations ranged from 19.2 to 127.4 μg/m³. SO₂and O₃were not associated with daily mortality. The exposure-response relationships demonstrated heterogeneity, with some curves showing nonlinear relationships for SO₂and O₃. We conclude that there is consistent evidence of acute effects of NO₂on mortality and suggest that a no-threshold linear relationship exists between NO₂and mortality.     

Characterization of Air Quality Problems in Five Finnish Indoor Ice Arenas

ABSTRACT

The air quality in five Finnish ice arenas with different volumes, ventilation systems, and resurfacer power sources (propane, gasoline, electric) was monitored during a usual training evening and a standardized, simulated ice hockey game. The measurements included continuous recording of carbon monoxide (CO), nitric oxide (NO), and nitrogen dioxide (NO₂) concentrations, and sampling and analysis of volatile organic compounds (VOCs). Emissions from the ice resurfacers with combustion engines caused indoor air quality problems in all ice arenas. The highest 1-hour average CO and NO₂ concentrations ranged from 20 to 33 mg/m³ (17 to 29 ppm) and 270 to 7440 µg/m³ (0.14 to 3.96 ppm), respectively. The 3-hour total VOC concentrations ranged from 150 to 1200 µg/m³. The highest CO and VOC levels were measured in the arena in which a gasoline-fueled resurfacer was used. The highest NO₂ levels were measured in small ice arenas with propane-fueled ice resurfacers and insufficient ventilation.

In these arenas, the indoor NO₂ levels were about 100 times the levels measured in ambient outdoor air, and the highest 1-hour concentrations were about 20 times the national and World Health Organization (WHO) health-based air quality guidelines. The air quality was fully acceptable only in the arena with an electric resurfacer. The present study showed that the air quality problems of indoor ice arenas may vary with the fuel type of resurfacer and the volume and ventilation of arena building. It also confirmed that there are severe air quality problems in Finnish ice arenas similar to those previously described in North America.     

Vegetation: A Sink for Atmospheric Pollutants

The possibility of vegetation being an important sink for gaseous air pollutants was investigated. Plant pollutant uptake measurements were made utilizing a typical vegetation canopy and chambers that were designed specifically for gaseous exchange studies. The data indicate that an alfalfa canopy removed gases from the atmosphere in the following order: hydrogen fluoride (HF) > sulfur dioxide (SO₂) > chlorine (Cl₂) > nitrogen dioxide (NO₂) > ozone (O₃) > peroxyacetyl nitrate (PAN) > nitric oxide (NO) > carbon monoxide (CO). The absorption rate of NO was low, and no absorption of CO could be detected with the methods used. In the typical ambient concentration range uptake increased linearly with increasing concentration except for O₃ and Cl₂ which caused partial stomatal closure at the higher concentrations. Wind velocity above the plants, height of the canopy, and light intensity were shown to affect the pollutant removal rate. A relationship between the absorption rate and solubility of the pollutant in water was also shown. It was concluded that vegetation may be an important sink for many gaseous air pollutants.     

Detection and Measurement of Air Pollutants by Absorptions of Infrared Radiation

A technique of detecting gaseous air pollutants by means of absorption of laser radiation is under development at the NASA Electronics Research Center. The iodine infrared laser and the carbon dioxide infrared laser are forced to emit spectral lines which fall on the infrared absorption bands of atmospheric pollutants. The attenuation of a laser line when passed through an air sample is the measure of the pollutant concentration. The narrow spectral width of the laser emission permits sensitive detection, minimizes interference between pollutants, and allows penetration of atmospheric water bands. The collimation and high power outputs available from lasers permit transmission of the radiation over long straight paths through the atmosphere and over long folded paths in multiple-pass absorption cells. A sample of absorbing gas placed within the laser cavity forces the emission of the selected wavelengths. With a one-half kilometer path to a retro-reflector and back, it is predicted that the following concentrations of air pollutants will be detected by means of the indicated laser lines: carbon monoxide at 2 parts per million in air (ppm), using the 4.86 micron iodine line; nitric oxide at 1 ppm, using the 5.5 micron iodine line; ethylene at 0.1 ppm, using the 10.53 micron carbon dioxide line; sulfur dioxide at 1.5 ppm, using the 9.08 micron carbon dioxide line; and ozone at 0.15 ppm, using the 9.52 micron carbon dioxide line. It seems feasible to extend the technique to other gaseous pollutants such as nitrogen dioxide, methane, butane, and peroxy acetyl nitrate. Continuing effort is being devoted to development and construction of the laser transmitting and receiving equipment. Field testing is planned for the near future.     

NCAQ Report to Congress: Review and Response

Airborne measurements of gaseous and particulate sulfur and nitrogen pollutants were made in southwestern Kentucky on the afternoon of October 21, 1979. Back-trajectory analysis indicates that the sampled air parcel moved over northern Florida, Alabama, and western Tennessee during the two days prior to sampling. Before moving over Florida, the air parcel was over the Atlantic Ocean for at least five days. Analytical long-range transport (LRT) model predictions based on anthropogenic emissions account for only about 75% of the airborne measured concentrations of 14.7 μg m^?3 for SO₂ and 4.8 μg m^?3 for SO₄ ^2?. The remaining 25 % is thought to be due to biogenic sulfur emissions from the extensive wetland areas along the Gulf Coast.

Forward-trajectory analysis indicates that the air parcel moved to the Adirondack Mountains of New York State 24 hours after sampling. Model predictions indicate that SO₂ and SO₄ ^2? mean layer concentrations at the Adirondacks were 24 and 16 μg^?3, respectively. Almost half of this sulfur was estimated to come from emissions in the heavily industrialized region along the Ohio River Valley.

Further comparisons used a measurement data base obtained in southeastern Canada and the state of Arkansas during August 1976. An air parcel was tracked for seven days as it entered the north central United States, stagnated over the lower midwest, and then moved to eastern Canada. Model predictions were in substantial agreement with regional SO₄ ^2? concentrations measured at a number of ground-level sites. Average SO₄ ^2? concentrations measured in central Arkansas on August 10, 1976 were 20 μ m^?3 vs. a modeled value of 19 μ m^?3. Average SO₄ ^2? concentrations measured in Nova Scotia four days later were 22 μg^?3 vs. a modeled estimate of 24 μg^?3.     

Quantification and Analysis of Airborne Bacterial Characteristics in a Nursing Care Institution

ABSTRACT

Indoor air quality has become a critical issue because people spend most of their time in the indoor environment. The factors that influence indoor air quality are very important to environmental sanitation and air quality improvement. This study focuses on monitoring air quality, colony counts, and bacteria species of the indoor air of a nursing care institution. The regular colony counts in two different wards range from 55 to 600 cfu m^?3. Regression analysis results indicate that the bacterial colony counts have close correlation with relative humidity or carbon dioxide (CO₂) but not with carbon monoxide (CO) or ozone (O₃). Real-time PCR was used to quantify the bacterial pathogens of nosocomial infection, including Acinetobacter baumannii, Citrobacter freundii, Escherichia coli, Klebsiella pneumoniae, and methicillin-sensitive Staphylococcus aureus. The most abundant bacteria species in the air of the nursing care institution is E. coli.

IMPLICATIONS Indoor temperature, humidity, ventilation, accumulation of biological pollutants, and potential infection problems will seriously affect the indoor environments. Studying these factors is important to indoor environmental sanitation and air quality improvements. Results of using real-time PCR to evaluate the bacterial pathogens of nosocomial infection for a nursing care institution in Taiwan reveal that the main bacteria species existing in the indoor air is E. coli.     

An aerosol injection and outdoor chamber system for the study of atmospheric gasparticle reactions

A system for the study of reactions between particle bound organic compounds and gaseous pollutants is described. The system is based on two 25 m³ outdoor smog chambers and associated equipment. Injection of sub-μm diameter carbon black particles is achieved using a liquid nitrogen based injection system. Suspended mass half life in the chamber is increased from 0.8 to 5.8 h by the use of a bipolar ion atmosphere. Particle concentrations and size distributions are shown to be similar to those obtained from wood combustion.     

Effect of outside air ventilation rate on volatile organic compound concentrations in a call center

A study of the relationship between outside air ventilation rate and concentrations of volatile organic compounds (VOCs) generated indoors was conducted in a call center office building. The building, with two floors and a total floor area of 4600 m², is located in the San Francisco Bay Area, CA. Ventilation rates were manipulated with the building's four air handling units (AHUs). VOC and CO₂ concentrations in the AHU returns were measured on 7 days during a 13-week period. VOC emission factors were determined for individual zones on days when they were operating at near steady-state conditions. The emission factor data were subjected to principal component (PC) analysis to identify groups of co-varying compounds. Potential sources of the PC vectors were ascribed based on information from the literature. The per occupant CO₂ generation rates were 0.0068–0.0092 l s⁻¹. The per occupant isoprene generation rates of 0.2–0.3 mg h⁻¹ were consistent with the value predicted by mass balance from breath concentration and exhalation rate. The relationships between indoor minus outdoor VOC concentrations and ventilation rate were qualitatively examined for eight VOCs. Of these, acetaldehyde and hexanal, which likely were associated with material sources, and decamethylcyclopentasiloxane, associated with personal care products, exhibited general trends of higher concentrations at lower ventilation rates. For other compounds, a clear inverse relationship between VOC concentrations and ventilation was not observed. The net concentration of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate isomers, examples of low-volatility compounds, changed very little with ventilation likely due to sorption and re-emission effects. These results illustrate that the efficacy of ventilation for controlling VOC concentrations can vary considerably depending upon the operation of the building, the pollutant sources and the physical and chemical processes affecting the pollutants. Thus, source control measures, in addition to adequate ventilation, are required to limit concentrations of VOCs in office buildings.     

Microscale air quality impacts of distributed power generation facilities

The electric system is experiencing rapid growth in the adoption of a mix of distributed renewable and fossil fuel sources, along with increasing amounts of off-grid generation. New operational regimes may have unforeseen consequences for air quality. A three-dimensional microscale chemical transport model (CTM) driven by an urban wind model was used to assess gaseous air pollutant and particulate matter (PM) impacts within ~10 km of fossil-fueled distributed power generation (DG) facilities during the early afternoon of a typical summer day in Houston, TX. Three types of DG scenarios were considered in the presence of motor vehicle emissions and a realistic urban canopy: (1) a 25-MW natural gas turbine operating at steady state in either simple cycle or combined heating and power (CHP) mode; (2) a 25-MW simple cycle gas turbine undergoing a cold startup with either moderate or enhanced formaldehyde emissions; and (3) a data center generating 10 MW of emergency power with either diesel or natural gas-fired backup generators (BUGs) without pollution controls. Simulations of criteria pollutants (NO₂, CO, O₃, PM) and the toxic pollutant, formaldehyde (HCHO), were conducted assuming a 2-hr operational time period. In all cases, NO_x titration dominated ozone production near the source. The turbine scenarios did not result in ambient concentration enhancements significantly exceeding 1 ppbv for gaseous pollutants or over 1 µg/m³ for PM after 2 hr of emission, assuming realistic plume rise. In the case of the datacenter with diesel BUGs, ambient NO₂ concentrations were enhanced by 10–50 ppbv within 2 km downwind of the source, while maximum PM impacts in the immediate vicinity of the datacenter were less than 5 µg/m³.

Implications: Plausible scenarios of distributed fossil generation consistent with the electricity grid’s transformation to a more flexible and modernized system suggest that a substantial amount of deployment would be required to significantly affect air quality on a localized scale. In particular, natural gas turbines typically used in distributed generation may have minor effects. Large banks of diesel backup generators such as those used by data centers, on the other hand, may require pollution controls or conversion to natural gas-fired reciprocal internal combustion engines to decrease nitrogen dioxide pollution.     

Daily Mortality and Air Pollution in the Netherlands

ABSTRACT

We studied the association of daily mortality with short-term variations in the ambient concentrations of major gaseous pollutants and PM in the Netherlands. The magnitude of the association in the four major urban areas was compared with that in the remainder of the country. Daily cause-specific mortality counts, air quality, temperature, relative humidity, and influenza data were obtained from 1986 to 1994. The relationship between daily mortality and air pollution was modeled using Poisson regression analysis. We adjusted for potential confounding due to long-term and seasonal trends, influenza epidemics, ambient temperature and relative humidity, day of the week, and holidays, using generalized additive models.

Influenza episodes were associated with increased mortality up to 3 weeks later. Daily mortality was significantly associated with the concentration of all air pollutants. An increase in the PM₁₀ concentration by 100 u.g/m³ was associated with a relative risk (RR) of 1.02 for total mortality. The largest RRs were found for pneumonia deaths. Ozone had the most consistent, independent association with mortality. Particulate air pollution (e.g., PM₁₀, black smoke [BS]) was not more consistently associated with mortality than were the gaseous pollutants SO₂ and NO₂. Aerosol SO₄ ^-2, NO₃ ^-, and BS were more consistently associated with total mortality than was PM₁₀. The RRs for all pollutants were substantially larger in the summer months than in the winter months. The RR of total mortality for PM₁₀ was 1.10 for the summer and 1.03 for the winter. There was no consistent difference between RRs in the four major urban areas and the more rural areas.     

Volatile organic compounds at swine facilities: A critical review

Volatile organic compounds (VOCs) are regulated aerial pollutants that have environmental and health concerns. Swine operations produce and emit a complex mixture of VOCs with a wide range of molecular weights and a variety of physicochemical properties. Significant progress has been made in this area since the first experiment on VOCs at a swine facility in the early 1960s. A total of 47 research institutions in 15 North American, European, and Asian countries contributed to an increasing number of scientific publications. Nearly half of the research papers were published by U.S. institutions.Investigated major VOC sources included air inside swine barns, in headspaces of manure storages and composts, in open atmosphere above swine wastewater, and surrounding swine farms. They also included liquid swine manure and wastewater, and dusts inside and outside swine barns. Most of the sample analyses have been focusing on identification of VOC compounds and their relationship with odors. More than 500 VOCs have been identified. About 60% and 10% of the studies contributed to the quantification of VOC concentrations and emissions, respectively. The largest numbers of VOC compounds with reported concentrations in a single experimental study were 82 in air, 36 in manure, and 34 in dust samples.The relatively abundant VOC compounds that were quantified in at least two independent studies included acetic acid, butanoic acid (butyric acid), dimethyl disulfide, dimethyl sulfide, iso-valeric, p-cresol, propionic acid, skatole, trimethyl amine, and valeric acid in air. They included acetic acid, p-cresol, iso-butyric acid, butyric acid, indole, phenol, propionic acid, iso-valeric acid, and skatole in manure. In dust samples, they were acetic acid, propionic acid, butyric acid, valeric acid, p-cresol, hexanal, and decanal. Swine facility VOCs were preferentially bound to smaller-size dusts.Identification and quantification of VOCs were restricted by using instruments based on gas Chromatography (GC) and liquid chromatography (LC) with different detectors most of which require time-consuming procedures to obtain results. Various methodologies and technologies in sampling, sample preparation, and sample analysis have been used. Only four publications reported using GC based analyzers and PTR-MS (proton-transfer-reaction mass spectrometry) that allowed continuous VOC measurement. Because of this, the majority of experimental studies were only performed on limited numbers of air, manure, or dust samples. Many aerial VOCs had concentrations that were too low to be identified by the GC peaks.Although VOCs emitted from swine facilities have environmental concerns, only a few studies investigated VOC emission rates, which ranged from 3.0 to 176.5 mg d⁻¹ kg⁻¹ pig at swine finishing barns and from 2.3 to 45.2 g d⁻¹ m⁻² at manure storages. Similar to the other pollutants, spatial and temporal variations of aerial VOC concentrations and emissions existed and were significantly affected by manure management systems, barn structural designs, and ventilation rates.Scientific research in this area has been mainly driven by odor nuisance, instead of environment or health concerns. Compared with other aerial pollutants in animal agriculture, the current scientific knowledge about VOCs at swine facilities is still very limited and far from sufficient to develop reliable emission factors.     

A biochar-based medium in the biofiltration system: Removal efficiency,microorganism propagation,and the medium penetration modeling

Biofiltration is a method of biological treatment belonging to cleaner technologies because it does not produce secondary air pollutants, but helps to integrate natural processes in microorganisms for decomposing volatile air pollutants and solving odor problems. The birch wood biochar has been chosen as a principal material for biofilter bed medium. The experiments were conducted at the temperatures of 24, 28, and 32 °C, while the concentration of acetone, xylene, and ammonium reached 300 mg/m³ and the flow rate was 100 m³/hr. Before passing through the stage of the experimental research into the packing material inside biofilters, microorganisms were introduced. Four strains of microorganisms (including micromycetes Aspergillus versicolor BF-4 and Cladosporium herbarum 7KA, as well as yeast Exophiala sp. BF1 and bacterium Bacillus subtilis B20) were selected. At the inlet loading rate of 120 g/m³/hr, the highest elimination capacity of xylene in the biochar-based biofilter with the inoculated medium was 103 g/m³/hr, whereas that of ammonia was 102 g/m³/hr and that of acetone was 97 g/m³/hr, respectively. The maximum removal efficiency reached 86%, 85%, and 81%, respectively. The temperature condition (though characterized by some rapid changes) can hardly have a considerable influence on the biological effect (i.e., microbiological activity) of biofiltration; however, it can cause the changes in physical properties (e.g., solubility) of the investigated compounds.

Implications: The birch biochar can be successfully used in the biofiltration system for propagation of inoculated microorganisms, biodegrading acetone, xylene, and ammonia. At the inlet loading rate of 120 g/m³/hr, the highest elimination capacity of xylene was 103 g/m³/hr, that of ammonia was 102 g/m³/hr, and that of acetone was 97 g/m³/hr, respectively. The morphological structure of biochar can be affected by the aggressive air contaminants, causing the change in the medium specific surface area, which is one of the factors controlling the biofilter performance. Although biological effects in biofiltration are typically considered to be more important than physical effects, the former may be more important for compounds with high Henry’s Law coefficient values, and the biofilter design should thus provide conditions for better compound absorption.     

Evaluation of the Sodium Arsenite Method for Measurement of NO2 in Ambient Air

The sodium arsenite method for measurement of nitrogen dioxide in ambient air was evaluated. The method has a constant-high collection efficiency (82%) for nitrogen dioxide, and is insensitive to normal variations in operating parameters. Nitric oxide and carbon dioxide are positive and negative interferents, respectively. The combined average effect of these interferents, over ambient levels, is a positive bias of 9.9 µg/m³. This bias, although statistically significant, is minor ( 10 % ) in relation to the ambient air standard of 100 µg NO₂/m³ and does not warrant modification of the method to remove the interference.