Hung-Soo Joo

Bioremediation of oil-contaminated soil using Candida catenulata and food waste

Even though petroleum-degrading microorganisms are widely distributed in soil and water, they may not be present in sufficient numbers to achieve contaminant remediation. In such cases, it may be useful to inoculate the polluted area with highly effective petroleum-degrading microbial strains to augment the exiting ones. In order to identify a microbial strain for bioaugmentation of oil-contaminated soil, we isolated a microbial strain with high emulsification and petroleum hydrocarbon degradation efficiency of diesel fuel in culture. The efficacy of the isolated microbial strain, identified as Candida catenulata CM1, was further evaluated during composting of a mixture containing 23% food waste and 77% diesel-contaminated soil including 2% (w/w) diesel. After 13 days of composting, 84% of the initial petroleum hydrocarbon was degraded in composting mixes containing a powdered form of CM1 (CM1-solid), compared with 48% of removal ratio in control reactor without inoculum. This finding suggests that CM1 is a viable microbial strain for bioremediation of oil-contaminated soil with food waste through composting processes.

Measuring concentrations of ammonia in ambient air or exhaust air stream using acid traps.

Strong acid solutions have been widely used in acid traps to determine concentrations of ammonia in ambient air or exhaust air stream. A literature survey indicates the method has a long history and a wide variation in use. Through a series of studies, this paper examines several factors including volume of the acid, depth of the acid, and airflow rate; that might affect the efficiency of sulfuric acid traps and recommends steps researchers and other users may take to ensure reliable results from this method. The results from these series of studies indicate: (i) an inverse relationship between the efficiency of the acid traps and the amount of ammonia to be trapped even when the capacity of the acid trap is excessively greater than the maximum theoretical stoichiometric capacity needed to dissolve all of the ammonia, (ii) for the same volume of acid, the efficiency of the acid trap increased with the acid depth but overall, the efficiency at any given acid depth decreased as the amount of ammonia through the trap increased, and (iii) at the two airflow rates examined in this study (0.5 and 1.0 L/min) the efficiency of the acid traps decreased at similar rates as the concentration of ammonia in the sample air increased but the efficiency of the trap was significantly higher at the lower airflow rate. To obtain reliable measurements from this method, therefore, multi-point calibrations within the entire range of target measurements is recommended to provide accurate corrections of the measurements.

Reduction of volatile fatty acids and odor offensiveness by anaerobic digestion and solid separation of dairy manure during manure storage.

Volatile fatty acids (VFA) play an important role in the biodegradation of organic wastes and production of bioenergy under anaerobic digestion, and are related to malodors. However, little is known about the dynamics of VFA during dairy manure storage. This study evaluated the characteristics of VFA in dairy manure before and after anaerobic co-digestion in a laboratory experiment using eight lab-scale reactors. The reactors were loaded with four different types of dairy manure: (1) liquid dairy manure from a freestall barn, (2) mixture of dairy manure and co-digestion food processing wastes at the inlet of an anaerobic digester, (3) effluent from the digester outlet, and (4) the liquid fraction of effluent from a solid separator. Four VFA (acetic, propionic, butyric, and 2-methylbutyric acids) were identified and quantified in weekly manure samples from all reactors. Results showed that the dominant VFA was acetic acid in all four manure sources. The off-farm co-digestion wastes significantly increased the total VFA concentrations and the proportions of individual VFA in the influent. The dairy manure under storage demonstrated high temporal and spatial variations in pH and VFA concentrations. Anaerobic digestion reduced the total VFA by 86%-96%; but solid-liquid separation did not demonstrate a significant reduction in total VFA in this study. Using VFA as an indicator, anaerobic digestion exhibited an effective reduction of dairy manure odor offensiveness.

Reliable low-cost devices for monitoring ammonia concentrations and emissions in naturally ventilated dairy barns

This research investigated the use of two relatively cost-effective devices for determining NH3 concentrations in naturally ventilated (NV) dairy barns including an Ogawa passive sampler (Ogawa) and a passive flux sampler (PFS). These samplers were deployed adjacent to sampling ports of a photoacoustic infrared multigas spectroscope (INNOVA), in a NV dairy barn. A 3-day deployment period was deemed suitable for both passive samplers. The correlations between concentrations determined with the passive samplers and the INNOVA were statistically significant (r = 0.93 for Ogawa and 0.88 for PFS). Compared with reference measurements, Ogawa overestimated NH3 concentrations in the barn by ∼ 14%, while PFS underestimated NH3 concentrations by ∼ 41%. Barn NH3 emission factors per animal unit (20.6-21.2 g d(-1) AU(-1)) based on the two passive samplers, after calibration, were similar to those obtained with the reference method and were within the range of values reported in literature.

Impact of Anaerobic Digestion of Liquid Dairy Manure on Ammonia Volatilization Process

Abstract. The goal of this study was to determine the effect of anaerobic digestion (AD) on the mechanism of ammonia volatilization from liquid dairy manure, in storage or treatment lagoon, prior to land application. Physical-chemical properties of liquid dairy manure, which may affect ammonia volatilization process, were determined before and after AD. The properties of interest included: particle size distribution (PSD), total solids (TS), volatile solids (VS), viscosity, pH, total ammoniacal nitrogen (TAN), and ionic strength (IS). The overall mass transfer coefficient of ammonia (KoL) and the NH3 fraction of TAN (I²) for the undigested (UD) and AD manures were then experimentally determined in a laboratory convective emission chamber (CEC) at a constant wind speed of 1.5 m s-1 and fixed air temperature of 25 °C at liquid manure temperatures of 15, 25, and 35 °C. The PSD indicated non-normal left skewed distribution for both AD and UD manures particles, suggestive of heavier concentrations of particles towards the lower particle size range. The volume median diameters (VMD) for solids from UD and AD were not significantly different (p= 0.65), but the geometric standard deviations (GSD) were significantly different (p = 0.001), indicating slightly larger particles but more widely distributed solids in UD than AD manure. Results also indicated significantly higher pH, TAN, ionic strength (IS) and viscosity in AD manure. The KoL and I² for AD manure determined under identical conditions (air temperature, liquid temperature, and airflow) were significantly higher (p > 0.05) than for UD manure. Overall, these findings suggest that AD of dairy manure significantly increased initial ammonia volatilization potential from liquid dairy manure; with the largest increase (~62%) emanating from increased ammonium dissociation. The initial flux of ammonia, during the experiment period, was ~84% more from AD than in UD dairy manure.

Simulation of Ammonia Emissions from Scrape and Flushed Dairy Manure Post-Collection Storages

Manure scraping and flushing are the two common manure handling systems in concentrated animal feeding operations (CAFOs) in the United States. Previous studies have reported on the impacts of these two manure handling systems on ammonia emissions within barns. There are no studies comparing the impacts of the two manure handling systems on ammonia emissions during post-collection storages in lagoons and other similar manure storages although these facilities are known to account for the largest portion of ammonia volatilization in CAFOs. A series of bench scale experiments were conducted for a period of 23 days in controlled laboratory conditions to quantify and compare ammonia losses from typical storages of simulated scraped manure, and simulated flushed manure. Ammonia emission fluxes estimates (with cumulative ammonia emissions in the parentheses) over a 23-day period were 2.25±0.08g/m2/day (2034±106.5 mg) from the simulated scraped manure storage, 2.04±0.04g/m2/day (1739.3±53.3 mg) from the simulated flushed manure storages with 411 cm2 exposed surface area each, and 4.62±0.13g/m2/day (1752±56.3 mg) from the simulated scraped manure with 183 cm2 exposed surface area, respectively. These results indicate that ammonia emission fluxes from scraped manure storage would be more than from flushed manure storage by at least two times if both manure post-storages had approximately the same exposed surface area to the volume ratio. However, results also revealed significantly higher cumulative ammonia emissions from simulated scraped manure storage with 411 cm2 than from both the simulated flushed manure storage with 411 cm2 and the simulated scraped manure storage with 183 cm2 exposed surface areas.

A Method for Determination of Pollutant Emissions from Naturally Ventilated Freestall Dairy Barns

In mechanically-ventilated freestall dairy barns, pollutant emissions can accurately be determined from the differences in concentrations between the influent and exhaust gases and the measured flow of the ventilating air. In contrast, emissions from naturally ventilated (NV) freestall dairy barns do not have well defined specific air entry or exit points. In addition, pertinent airflow characteristics (velocity and direction) vary continuously, both temporally and spatially. This scenario significantly complicates the determinations of emissions. This paper examines a method being developed and tested for determining emissions from NV livestock barns. The method essentially entails placement of sonic anemometers (to measure air movement in and out of the structure) at salient points all around the barn in order to determine the airflow characteristics. Air samples are simultaneously collected at these selected points to determine the respective representative concentrations of the air entering or leaving the barn over a given sampling cycle or time. The airflow data is subsequently coupled with pollutant concentrations data to determine respective emissions from the barn. Results indicate credibility of sonic anemometers in the determination of ventilation characteristics in naturally ventilated barns, which are critical to accurate determination of pollutant emissions calculations from such barns.

Oxidative potential of fine ambient particles in various environments

The oxidative potential (OP) and chemical characteristics of fine particles collected from urban, roadside, rural, and industrial sites in Korea during spring, summer, fall, and winter seasons and an urban site in the Philippines during dry and wet seasons were examined. Significant differences in the OP of fine particles among sites and seasons were found. The industrial site yielded the highest OP activity (both mass and volume-normalized OP) among the sites, suggesting the strongest reactive oxygen species (ROS)-generating capability of industry source-dominant PM2.5. Seasonal data show that OP activities increased during the spring and summer possibly due to increased heavy metals caused by dust events and secondary organic aerosols formed by strong photochemical activity, respectively. The strength of the OP association with the chemical components highlights the influence of organic carbon and transition metals on the OP of ambient fine particles. The two OP assays (dithiothreitol (DTT) and electron spin resonance (ESR)) having different ROS-generating mechanisms were found to have different sensitivities to the chemical components facilitating a complementary analysis of the OP of ambient fine particles. Multiple linear regression model equations (OP as a function of chemical components) which were dependent on the sites were derived. A comparison of the daily OP and hazard index (HI) (the ratio of the measured mass concentration to the reference mass concentration of fine particles) suggests that the HI may not be sufficient to accurately estimate the health effects of fine particles, and a direct or indirect measurement of toxicity such as OP should be required in addition to the concentration level.

Effects of Anaerobic Digestion and Application Methods on Ammonia Emission from Land Applied Dairy Manure

Abstract. Ammonia emission from manure following land application reduces fertilizer value of the manure and could have adverse impacts on the environment. Manure pretreatments and methods of manure application, however, may impact ammonia volatilization. Field- and lab-scale experiments were conducted to study the effects of anaerobic digestion (AD) and manure application methods (surface application and manure injection) on ammonia emission. In general, most of the ammonia emissions occurred within 5 d after manure application. Soils receiving undigested manure (UM) emitted more ammonia than soils receiving digested manure (DM) irrespective of manure application method. Surface-applied DM resulted in 56% less ammonia emission than surface-applied UM, while injected DM emitted 27% less than injected UM. Although injected DM did not significantly affect ammonia emission for both application methods, injected UM resulted in 42% less ammonia emission than surface applied UM. Surface application of UM exhibited the highest ammonia emission flux (0.78 g m -2 d -1 ) immediately after application but the flux dropped to zero within 3 d. The lowest initial ammonia flux of 0.17 g m -2 d -1 , which gradually approached zero within 5 d, was observed from injected DM. Similar results were obtained from field studies as follows. Surface applied DM resulted in 49% less ammonia emission than surface applied UM. Surface application resulted in 63% and 25% more ammonia loss than manure injection for UM and DM, respectively. Manure injection was thus a more effective method for mitigation of ammonia emission than surface application. Together, these studies indicate that land application of DM is both economically (retention of manure fertilizer-value) and environmentally friendlier (reduced ammonia emissions) than application of raw manure or UM.

Effect of Anaerobic Digestion on Volatile Fatty Acids in Dairy Manure

This paper presents study results of volatile fatty acids (VFA) production during three months of storage of dairy manure collected from four different sources: (1) a dairy barn, (2) the inlet of an anaerobic digester (influent), (3) the outlet of the digester (effluent), and (4) the effluent after separation of biosolids. Manure from each source was tested in two lab-scale bioreactors of 61.0 cm high and 38.1 cm in diameter. Each bioreactor was initially filled with manure to as depth of 25.4 cm. The bioreactors were continuously ventilated with 6.5 L/min of fresh air in the manure headspace during the entire test to simulate manure storage conditions on dairy farms. Two manure samples were taken weekly from each bioreactor for VFA concentration analysis: one in the top manure layer within 2.5 cm below the surface and another in the bottom manure layer within 5.0 cm above the reactor bottom. Five VFA including: formic acid, acetic acid, propionic acid, butyric acid, and 2-methylbutyric acid, were identified in manure samples from all reactors using HPLC (High Performance Liquid Chromatography). Significant differences in VFA concentrations between the digested and undigested manure were observed. Results showed that the dominant VFA in the stored manure from the dairy barn was acetic acid followed by propionic acid. Concentrations began to decline around the fifth week of storage. The stored influent manure had initial formic acid concentrations as high as 27 g/L, but the concentration declined within 4 wks of storage. The acetic and butyric acids were the dominant VFA after the decline of formic acid. For all digested manure, the dominant VFA was acetic acid but its concentrations only reached a maximum of 0.9 g/L compared with a maximum concentration of 5 g/L in influent manure. This study provides a better understanding of the environmental effects of anaerobic digestion on the dairy manure storage.