• Journal of environmental and Sanitary engineering
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• v.15 no.3
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• pp.24-30
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• 2000

In this study, to determine the optimum fermentation process for the feed production of food wastes and estimate the practical value of fermented feed using kudzu creeper and sawdust as bulking agent. This study considered initial C/N ratio control as the fermentation process variables. The result are summarized as follows. Minimum water contents of byproducts in the fermentation feed production showed 39%(kudzu), 37%(sawdust) at the C/N ratio 25 and 45%(kudzu, sawdust) at the C/N ratio 35. Temperature variations in the fermentation feed production at the C/N ratio 25 indicated $68^{\circ}C$(kudzu), $70^{\circ}C$(sawdust). Optimum condition of fermentation process of water content, C/N ratio and permeability (porous structure of the mixture). For optimum fermentation gravitationally dewatered garbage, the proper mixing ratios of kudzu(moisture contents : 17.3%) and sawdust(moisture contents : 13.2%) were 41% and 39%, respectively. Major biological reaction in the aerobic fermentation feed production occurred during 12~24hrs.

• Journal of Environmental Health Sciences
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• v.29 no.2
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• pp.56-61
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• 2003

This study was performed to examine the effects of chaff as a bulking material on temperature, pH, weight and volume reduction and salinity in aerobic composting of food wastes. Volume ratios of food wastes to chaff in reactor of Control, Ch-1. Ch-2, Ch-3 and Ch-4 were 4:0, 4:1, 4:2, 4:3 and 4:4. respectively. Reactors were operated for 24 days with 1 hour stirring by 1 rpm and 2 hours aeration per day. The lowering of the volume ratio of food wasted to chaff resulted in the reaction at higher reaction temperature and the elongation of the high temperature reaction period. The lowering of the volume ratio of food wastes to chaff resulted in the more faster pH increase. The lowering of the volume ratio of food wastes to chaff resulted in the more faster reduction in the weight and the volume of wastes. Salinities were condensed by reaction days. The final salinity of Control and the final range of salinities of chaff mixtures were 2.79%, and 2.18~2.37%. respectively.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.468-474
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• 2006

In the secondary settling tanks, three different types of settling phenomena occurs; i.e., zone settling for sludge thickening in the bottom part of settling tank, and discrete and flocculent settling for clarification in the upper part. In this paper, morphological parameters of the floc in sludge blanket layers along the length of a long rectangular tank were investigated. The plant used for this study had a serious bulking problem caused by Microthrix parvicella. Floc size decreased as the surface area of settling tank increases, which indicates that in the secondary settling tank where zone settling believed to be predominant, free or flocculent type of settling contributes to floc size distributions. Large floc particles deposit in the front zone of settling tank, but small and loose flocs mostly in the zone near its outlet. On the other hand, filament length contained in one gram of sludge blanket solid increases along the flow direction. Large flocs with less filaments settle faster, but small flocs having more filaments result in poor settling. These results support function of microorganism selection occurring in secondary settling tank. In addition, designing a long rectangluar settling tank with double hoppers might be one of the ways of bulking control, but this idea has to be verified with a further study.

• Journal of Animal Environmental Science
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• v.4 no.1
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• pp.55-61
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• 1998

Cow feces excreted in cold season should be managed and composted properly, because the composted feces is distributed to pasture or cultivated land as a fertilizer in spring. Generally it is admitted that the effect of composting is suppressed by low temperature in cold season. In this study, composting piles were warmed by hot air until temperature of compost piles were reached at 35∼40$^{\circ}C$, to compare composting effect of experimental compost pile to control pile exposed in cold air. Some results obtained from the experiment during composting of cow feces mixed with bulking agent provide a possibility of active composting of organic matters in cold season. The biodegradation ratios of organic matter during composting in four types of composts were 10.2% for the rice straw, 7.7% for the rice hull, 6.4% for the sawdust and 4.3% for the control. The highest temperatures of compost piles during composting period were 76$^{\circ}C$ in sawdust, 80$^{\circ}C$ in rice hull, 68$^{\circ}C$ in rice straw, 45$^{\circ}C$ in control. Moisture content, pH, C/N, volume of compost were decreased during composting period, but EC value was increased with ionization of organic molecular by fermentation.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.43-50
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• 2003

This study was performed to compare the effects of rice straw and towage sludge cake as bulking materials on temperature, pH, weight and volume reduction, porosity, C/N ratio, salinity, and conductivity in aerobic composting of food wastes. Volume ratios of food wastes to rice straw in reactor control, RS-1, RS-2, RS-3 and RS-4 were 4:0, 4:1, 4:2, 4:3 and 4:4, respectively. Weight ratios of food wastes to sewage sludge rake in reactor control, SL-1, SL-2, SL-3 and SL-4 were 4:0, 4:1, 4:2, 4:3 and 4:4, respectively. Reactors were operated for 24 days with 1 hour stirring by 1 rpm and 2 hours aeration per day. The values of pH of food waters, rice straw and sewage sludge cake were 4.39, 7.40 and 5.79, respectively. The lowering of the volume ratio of food wastes to rice straw resulted in the high reaction temperature and the fast weight and volume reduction rates. The lowering of the weight ratio of food wastes to sewage sludge cake resulted in the slow weight and volume reduction rates. C/N ratio in control was larger than that in rice straw containing reactors, and that in rice straw containing reactors was larger than that in sewage sludge cake containing reactors. Salinity and conductivity in reactors were condensed and increased by reaction days.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.376-383
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• 2006

This study was undertaken to control sludge bulking and foaming problems at the biological nutrient removal processes. A sewage treatment plant(STP) had a severe sludge settling problem usually over 90% in 30 min settled sludge volume and 300 mL/g in SVI and also thick and heavy brown foam in the secondary clarifiers. Identification study shows that causative filament was Microthrix parvicella which has not been previously reported in Korea. According to the inspection of processes and other related parameters, excessive growth of this particular filament was associated with high SRT caused by lack of proper capacity in sludge treatment line. After providing an extension of the sludge treatment capability, the plant can decrease SRT by wasting more sludge from the processes and also decreasing SS concentration in recycled stream. Subsequently we were able to control growth of M. parvicella. The SVI value was reduced to half of those observed during the severe bulking, but also sludge blanket and its concentration in the clarifier became compact and dense. However, decrease in population of M. parvicella caused increase of total phosphorus concentration in the effluent.

• Journal of the Korean Society of Tobacco Science
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• v.15 no.1
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• pp.90-97
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• 1993

1. Average moisture content of tobacco in BIB silo was about 19: 1% until 4hours conditioned time, and then moisture variation of tobacco after 2hr conditioned was very small. 2. Application of mathematical model for ordering system. 1) The constant K in the exponential equation varies inversely with both relative humidity and equilibrium moisture. 2) Time needed to order blending tobacco leaves with standard moisture from bulking and blending silo was 4 hours. 3) Reconstituted tobacco sheet had higher moisture absorption ratio than Oriental and Burley tobacco. 4) For minimize of conditioning time in BIB silo, the values of K and Mo given in this study can be used in equation(1) to calculate moisture absorption ratio and optimum conditioning time. 3. Average moisture content and water activity of conditioned tobacco for 4 hours in BIB silo was about 20% and 0.65. In this condition. microbial life will inhibite 4. Physical properties of conditioned tobacco in bulking and blending silo for 4hours was virtually no change.

• Journal of environmental and Sanitary engineering
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• v.15 no.3
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• pp.23-23
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• 2000

In this study, to determine the optimum fermentation process for the feed production of food wastes and estimate the practical value of fermented feed using kudzu creeper and sawdust as bulking agent. This study considered initial C/N ratio control as the fermentation process variables. The results are summarized as follows. Minimum water contents of byproducts in the fermentation feed production showed 3994(kudzu), 37%( sawdust) at the C/N ratio 25 and 45%(kudzu, sawdust) at the C/N ratio 35. Temperature variations in the fermentation feed production at the C/n ratio 25 indicated 68'C(kudzu), 70'C (sawdust).Optimum condition of consists of fermentation process of water content, C/N ratio and permeability (porous structure of the mixture). For optimum fermentation of gravitationally, dewatered garbage, the proper mixing ratios of kudzu(moisture contents : 17.3%) and sawdust(moisture contents : 13.2%) were 41% and 39%, respectively Major biological reaction in the aerobic fermentation feed production occurred during 12~14hrs

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.4
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• pp.100-110
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• 2000

Studies were conducted to know effects of the bulking agents (saw dusts, mushroom waste, wheat bran coconut meal, rice hulls) adding o moisture control, fermentation methods (aerobic and anaerobic) and periods (1 to 20 days) of food waste fermentation for animal feeds on chemical compositions and in vitro DDM (digestibility of dry matter). Experiment designs were focussed basically to obtain extension service data. The NDF (neutral detergent fiber) composition in the oak and pine saw dust were 93.5% and 95.4% (DM basis) in respectively. Thus, the fermented food waste feeds using saw dust (50%) increased NDF(12%), and decreased in vitro DDM(48%) compared to those of raw materials before aerobic fermentation. The oak saw dust showed higher DDM compared to pine. Mushroom wastes which is a residues of mushroom culture mixed originally willow saw dust (80%) and wheat bran (20%) showed quite higher feed value compared to both saw dusts. It was found that an in vitro DDM and NDF composition in fermented feeds appeared highly dependent or the NDF composition in bulking agents. With an increase wheat bran ratio substitute mushroom waste showed linearly decreased NDF, and increased in vitro DDM in the fermented food waste feeds. The fermented feeds added bottling agents composed higher NDF resulted in higher NDF and lower in vitro DDM with prolonged fermentation time. The feeds from anaerobic fermentation appeared lower NDF and higher in vitro DDM compared to those of aerobic fermentation.

• Journal of Environmental Health Sciences
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• v.32 no.4 s.91
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• pp.353-358
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• 2006

This study was performed to evaluate the effects of input ratios of bulking material in aerobic composting of food wastes on variation of colony forming units of heterotrophic bacteria. Wood chips were used as a bulking material. Volume ratios of food wastes to wood chips in reactor of Control, WC-1 and WC-2 were 10/0, 10/5 and 10/10, respectively. Reactors were operated for 24 days with 1hour stirring by 1rpm and 2 hours of the forced aeration per day. WC-2 reached high temperature range faster than WC-1, and the maximum temperature of WC-2 was higher than that of WC-1. This means that the reaction velocity of composting of WC-2 was faster than that of WC-1. Judging from the profile of pH changes, composting of WC-1 proceeded slowly and continuously. Composting of WC-2 proceeded rapidly in the former half reaction period, and kept steady state of high pH in the latter half reaction period. Namely, composting of WC-2 was nearly completed in the former half reaction period. In the case of WC-1 and WC-2. the maximum temperature was followed by the rapid pH increase in 2-3 days, and this was followed by the maximum Colony Forming Units(CFU) in 3 days. But, these three items of WC-2 always appeared faster and higher than those of WC-1.