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

Complaints about foul odors are emerging as an issue, and the number of complaints is steadily increasing every year. Biofiltration is known to remove harmful or odorous substances from the atmosphere by using microorganisms, and full-scale biofilters are being installed and operated in various environmental and industrial facilities. In this study, the current status and actual odor removal efficiency of full-scale biofilters installed in publicly owned treatment facilities such as sewage, manure, and livestock manure treatment plants were investigated. In addition, the effects of design and operating factors on their efficiency were also examined. As a result, it was found that odor prevention facilities with less than 30% odor removal efficiency based on complex odors accounted for 40%-50% of the biofilters investigated. In investigating the appropriate level of operating factors on odor removal efficiency, it was found that compliance with the recommended values p lays a significant role in improving odor removal efficiency. In the canonical correlation analysis for the on-site biofilter operation and design data, residence time and humidity were found to be the most critical factors. The on-site biofilter operation and design data were analyzed through canonical correlation analysis, and the residence time and humidity maintenance were found to be the most important factors in the design and operations of the biofilter. Based on these results, it is necessary to improve the odor removal efficiency of on-site biofilters by reviewing the effectiveness of the operation factors, improving devices, and adjusting operating methods.

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.

Two lab-scale trickle-bed type biofilters with a single fungal species (Aspergillus fumigatus, Acidomyces acidophilus, respectively) have been studied to investigate the simultaneous removal of inorganic (hydrogen sulfide) and organic (butyl acetate) compounds. The biofilter with Aspergillus fumigatus treated simultaneously two different compounds with removal capacity of 1,511 mgS/m3/hr and 6,324 mgC/m3/hr; and the biofilter inoculated with Acidomyces acidophilus had the removal capacity of 1,254 mgS/m3/hr and 6,045 mgC/m3/hr. Stable operational performance was observed in both biofilters under an acidic condition of pH 2 to 4. Based on pseudo-first-order removal rates as a function of depth in the biofilter, Aspergillus fumigatus showed a twice faster rate of hydrogen sulfide removal than Acidomyces acidophilus, 15.9% (Aspergillus fumigatus) and 17.9% (Acidomyces acidophilus) of total sulfur removed were oxidized to produce sulfates, and 77.8% (Aspergillus fumigatus) and 79.4% (Acidomyces acidophilus) were accumulated in the form of S0 through the bed in both biofilters, respectively.

This study was conducted to evaluate the applicability of a carrier media with natural minerals as packing material in a biofilter to remove odor-causing compounds. The carriers were prepared by mixing powdered zeolite, barley stone, and clay. They have a pellet type with a length of 5m m to 10 mm, 3.2 m2/g of a specific surface area, and 0.04 cm3/g of a pore volume. The adsorption capacity and the biodegradation by biomass formation on the media were experimented with toluene and ammonia as the test compounds. The carrier possessed the ability to adsorb toluene and ammonia. The adsorption capacity of toluene and ammonia at the inlet concentration of 100 ppmv was 58 g/g and 96 g/g, respectively. In the biofilter using the carrier as the packing material, the biofilter performances were different depending on the supply of moisture and liquid-nutrient. The critical loading was found to be 33.13 g/m3/hr for toluene removal and 6.5g /m3/hr for ammonia removal even when no nutrients were supplied. The proposed material has been confirmed to be capable of adsorbing inorganic and organic compounds, and can be effectively applied as packing materials for the biofiltration.

A lab-scale biofilter with fungal growth has been studied to investigate the removal of gas-phase hydrogen sulfide. The biofilter inoculated initially with the aerobic activated sludge was operated for 100 days under acidic condition, and 0.36 L/d of the buffered nutrient with 0.05 g/L Chloramphenicol and Gentamicin was injected into the biofilter. The critical removal capacity of hydrogen sulfide was up to 22 g/m³/h. The pH of the effluent liquid was stable at pH 1.5-2, corresponding to the volatile suspended solids of 20-50 mg/L. In microbial analysis through the plate count method, it was found that fungi were dominant over bacteria. The fungi isolated from biomass in the bilfilter were identified as Acidomyces acidophilus and Aspergillus fumigatus. Sulfate and thiosulfate were also detected in liquid samples, as a result of the biological sulfur oxidation in the biofilter bed. For the analysis of sulfur mass balance, the accumulated mass of sulfate and thiosulfate reached up to 67.5% of inlet sulfur. Sulfur was also detected on the biomass collected from the biofilter through Scanning electron microscopy/Energy dispersive X-ray spectroscopy.

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

A biofilter filled with sintered glass media and wood bark media were developed and tested. Acetic acid and ammonia added in brewery wastewater were used as an artificial odor source. The Reynolds’ number (NRe) was below 130 in the loading range of 3~5 m3/m2-min, while the pressure drop was less than 6 mmH2O. The average removal efficiency of acetic acid was 87.6% and 71.5% at surface loading rate of 3.1 m3/m2-min and 4.4 m3/m2- min, respectively. The acetic removal capacities were 8.1~14.3 g/m3-min with the mass loading rates of 11.7~22.4 g/m3-min, indicating very high performance. However, the acetic removal capacity was sharply decreased at the mass loading rate of 20 g/m3-min. The average removal rate of ammonia was 38% and 25% at the surface loading rates of 3.1 m3/m2-min and 4.4 m3/m2-min, respectively. The ammonia removal capacity was 0.47~0.88 g/m3-min in the range of 11.7~22.4 g/m3-min mass loading rates. The intensity of complex odor was also decreased based on the findings in the measurement using the direct olfactory method and the GC analysis.

The objective of this study was to investigate the response characteristics and performance of a biofilter in the removal of ammonia, as a malodor compound. A trickle-bed type biofilter was applied for this study, and operated at the ammonia loading rate of 0.97-15.52 g/m3·h. The results of the experiment indicate that the critical loading rate of ammonia to the biofilter was 10.7 g/m3·h and the elimination capacity was 11.6 g/m3·h. The analysis of nitrogen mass balance in the reactor indicates that inlet nitrogen as gas phase was converted through the biofilter into NH4 + (41.5% by mass), NO2 - (43%), and NO3 - (15%) as the available form of nitrogen in the effluent liquid. Free ammonia concentration in the effluent liquid was estimated as being in the range from 0.14 to 2.93 mg/L (average 1.7 mg/L) during the experimental period.

본 논문은 음식물쓰레기의 퇴비화에 타당성을 위한 총론적인 논문이다, 또한 다양한 연구논문들을 조사함으로써 음식물 쓰레기의 퇴비화를 통해 얻어진 최종산물이 휘발성 유기화합물 및 냄새제거를 위한 바이오필터로서 적합성을 제고해 보고자 하였다. 우선 음식물쓰레기는 높은 유기물 함유량을 가지고 있어 퇴비화에 적합하지만 반면 높은 수분함량과 물리적으로 낮은 강도로 인해 퇴비화 과정을 어렵게 할 수 있다. 많은 연구자들에 의해 퇴비를 이용한 바이오필터링에 대한 연구가 진행중임에도 불구하고, 명확한 메커니즘의 규명이 되어 있지 않고 있으며 특히 음식물쓰레기에 대한 연구는 미비한 실정이다. 따라서 본 논문에서는 특히 음식물쓰레기 퇴비의 바이오필터로서의 사용가능성에 대한 기본적이고 중요한 자료를 제공하고자 한다.

The purpose of this study is to estimate the performance of various biofilter media using ammonia. The results can be summarized as follows: 1) The removal of ammonia using various biofilter media was performed, and inorganic media was proved to be better than the organic media. 2) From the inorganic media, fibril form was most superior. 3) Because fibril form is expensive, PU was determined to be the optimum biofiler media for ammonia removal.

The purpose of this experimental research was focused to improve the quality of the effluent and the yielded sludge when the papermill wastewater was treated by the indirect aerated submerged biofilter as a second treatment method of papermill wastewater. Changing the various experimental factors(Nutrient additions or not, HRT, F/M ratio, recirculation ratio, etc) with indirect aerated biofilter, the results obtained are as follows. 1. Because of the microbes concentration could be sustained to $9,000mg/l$ in submerged biofilter and then the volumetric organic loads could be increased to $2.7kg-BOD/m^3/day$(that of activated sludge is $0.8kg-BOD/m^3/day$), the reactor volume can be reduced to one third of the activated sludge treatment. 2. Because of the yield coefficient(Y) and the endogenous decay coefficient(kd) were revealed 0.4 and 0.07/d, the yielded sludge volume was reduced by for compared with that of the activated sludgg process. 3. The concentration of the sloughed sludge in the reactor was 2.62~4.01%, so the thickener could be omitted in the papermill wastewater sludge treatment process. 4. When the operating was conducted at HRT of 4hrs, the treatment efficiencies of BOD and COD were obtained 80% and 70%, Therefore operating time can be reduced to one half of the activated sludge treatment.

The final goal of this research is to develop a miniaturized botanical biofilter using a wick-typed automatic humidifier for stabilizing soil moisture content (SMC) and purifying indoor air pollutants by the biofilter. This new biofilter equipped with wick-typed automatic humidifier was manufactured as more compacted design removing an absorption tower-typed humidifier compared with the previous big-sized biofilter made in 2015. This study was performed to compare changes of SMCs among floors depending on the number of wicks installed on the humidifier within the novel biofilter, and to compare changes of SMCs and plant growth parameters before and after planting Spathiphyllum wallisii ‘Mauna Loa’ on the biofilter. SMCs among floors depending on the number of wicks were similar, and all regression lines of SMCs showed almost horizontal lines because of long-term stability on SMCs. Comparing plant growth parameters of S. wallisii ‘Mauna Loa’ before planting and at 30 days after planting on the biofilter, all growth parameters were not statistically significant. Thus, SMCs of the biofilter were more stabilized using this humidifying appar

The final goal of this research is to develop a botanical biofiltration system, which combines green interior, biofiltering, and automatic irrigation, which can purify indoor air pollutants according to indoor space and the size of biofilter. The biofilter used in this experiment was designed as an integral form of water metering pump, water tank, blower, humidifier, and multi-level planting space in order to be more suitable for indoor space utilization. This study was performed to compare indoor air quality between the space adjacent to a botanical biofilter and the space away from the biofilter (control) without generation of artificial indoor air pollutants, and to evaluate plant growth depending on multiple floors within the biofilter. Each concentration of indoor air pollutants such as TVOCs, monoxide, and dioxide in the space treated with the biofilter was lower than that of control. Dracaena sanderiana ‘Vitoria’ and Epipremnum aureum ‘N Joy’ also showed normal growth responses regardless of multiple floors within the biofilter. Hence, it was confirmed that the wall-typed botanical biofilter suitable for indoor plants was effective for indoor air purification.