• Journal of Animal Science and Technology
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• v.52 no.6
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• pp.513-519
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• 2010

A series of experiments were performed to study the influence of the following parameters on the physical traits and composition of swine manure compost: (1) addition of magnesium (Mg) at a molar ratio of 1.2 with respect to $PO_4$, and (2) reutilization of compost containing $MgNH_4PO_4{\cdot}6H_2O$ (magnesium ammonium phosphate, MAP). Three independent batch tests were conducted for replication: batch test I-control (C) and Mg added (T), batch test II-C, T and compost recycle ($T_{R1}$), and batch test III-C, T and compost recycle ($T_{R2}$). Magnesium addition and compost reutilization had no adverse effect on the degradation of organic matter. Reuse of the compost, however, had a clear effect on the total nitrogen (TN) and total phosphorus (TP) contents in the final compost. Repeated compost reutilization as a bulking material was resulted in composts rich in N and P. Upon adding the Mg supplement to the composting materials, the ortho-phosphate (OP) to TP ratio decreased due to the MAP crystallization reaction. The decrease in the OP/TP ratio and the increase in the TP content of the compost indicate that water-soluble phosphate is converted into a slow-release phosphate by the formation of crystals during composting. X-ray diffraction analysis of the irregular shaped crystals in the compost indicated that they are MAP crystals and that the crystallization of MAP begins immediately after the addition of the Mg supplement. The Mg addition to composting materials and the reutilization of compost as a bulking material would be a practical means to conserve nutrient content.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.5
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• pp.61-68
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• 2014

The energy efficiency of papermaking process becomes more significant because of various new regulation of the energy consumption and the green house gas emission. In this study, the effects of wood powder addition on the drainage and the drying efficiency of the OCC based paper products, linerboard, were deeply investigated for improving energy efficiency. The fractionation of wood powder depending on the size were conducted. The bigger size of wood powder resulted in the higher bulk and the higher drainage efficiency, but the lower paper strength. The drying efficiency were in detail evaluated depending on the drying process level. In the first section of drying process until the 80% solid level, there were no significant changes in the drying efficiency by the addition of wood powder. However, after the 80 % solid level, the drying efficiency was greatly improved by the addition of wood powder. Those results showed the addition of wood powder could greatly affect not only the drainage in forming and wet pressing but also the drying process.

• Journal of agriculture & life science
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• v.52 no.6
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• pp.81-88
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• 2018

This study analyzed the characteristics of 6 recyclable bulking agents which can replace sawdust and rice hulls that are commonly used in livestock manure composting. The content of all the hazardous chemicals found in the bulking agents used in this experiment was between 0.0 and 34.1 ppm, which was noticeably lesser than the maximum content levels of hazardous substances 5.0~900.0 ppm prescribed by the Rural Development Administration(RDA), which means that the bulking agents would be able to replace sawdusts and rice husks. The water content of the bulking agents ranged from a minimum of 12.4% to a maximum of 16.6% in the original state, which was much less than 60%, the optimal moisture content. These results indicate that they would be able to function fully as bulking agents. Their water absorption rate was in the range of minimum 31.9% ~ maximum 600.0%, which showed huge differences among the types of bulking agents. The most appropriate bulking agent in terms of water absorption rate was wood pellets. It was the highest in the wood briquette manufactured by A, which was followed by C and B in the order. The shear strength of the 5 types of bulking agents in the original state was 271.7 N on an average, the highest figure of all, except for the oak briquette whose shear strength could not be measured and the wood pellets in the absorption state. The shear strength in the dry and absorption states then followed, and were 78.0 N and 27.7 N on an average, respectively. The wood briquette of A recorded considerably lower shear strength than that of B and C. Overall, shear strength tended to increase according to lower water absorption rates. Since pine wood chips and oak cuts have relatively greater shear strength even in the absorbing state than the other materials, they will be able to endure some power in the case of stirring with pig droppings.

• 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 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.

• 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 Animal Environmental Science
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• v.21 no.3
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• pp.99-104
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• 2015

According to the volumetric mixing rate of dairy cow manure (DCM) and moisture control materials such as decomposed manure (DM) and sawdust (S), 6 reactors (DCM only (R1), DCM : DM = 1:1 (R2), DCM : DM = 1.5:0.5 (R3), DCM : DM = 0.5:1.5 (R4), DCM : DM:S = 1:0.5:0.5 (R5) and DCM : S = 1:1 (R6)) were used for composting of dairy cow manure. Among the composting reactors, composting reactor of R5 was shown the highest temperature of the compost as a $66^{\circ}C$ during composting period. After 3 weeks composting, moisture content of R5 and R6 were 51% and 51.3%, respectively. These values were satisfied with the moisture content standard of livestock manure compost of Korea. We concluded that decomposed manure may be a good moisture control material for dairy cow manure composting when it is used in mixture with sawdust. The optimum volumetric mixing ratio of dairy cow manure and moisture control materials was 50% of livestock manure, 25% of decomposed manure and 25% of sawdust.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.73-80
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• 2000

The objective of study was to evaluate the apropriate maturity indices for garbage composting using sawdust as bulking agent. Materials used in this study were the average composition garbage(G20) and garbage conditioned by sawdust(GS30, GS50) and cereals(GSC30). Indices for evaluating maturity were VS, water soluble TOC, polysaccharide, Humification Index(HI), and E4/E6. Experiment results showed that VS reduction was the most desirable index for evaluating compost maturity except for the GS50 which were conditioned with high sawdust Water soluble TOC decreased rapidly during the composting of first one month and then little changed. Therefore, water soluble TOC was recommended as maturity index. Polysaccharide was considered as a maturity index in case of garbage conditioned with sawdust and high cereals. Humification Index(HI) and E4/E6 were available as maturity indices in case of only some garbage composting so additional study was needed to confirm them as maturity indices for all garbage composting. Correlation analysis indicated that indices for evaluating maturity of garbage(about 30 C/N ratio) adding sawdust as bulking agent and high cereals, were VS reduction, water soluble TOC, polysaccharide, and E4/E6.

• Journal of Environmental Health Sciences
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• v.29 no.3
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• pp.28-34
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• 2003

This study was performed to compare the effects of chaff and sawdust as bulking materials 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-l, Ch-2, Ch-3 and Ch-4 were 4:0, 4:1, 4:2, 4:3 and 4:4, respectively. Volume ratios of food wastes to sawdust in reactor of Control, Sd-l, Sd-2, Sd-3 and Sd-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 wastes to chaff and sawdust 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 and sawdust resulted in faster pH increase. In the volume ratio of 4:3 and 4:4, pH increased faster in food-chaff mixtures than in food-sawdust mixtures. The lowering of the volume ratio of food wastes to chaff and sawdust resulted in faster steady state in the weight reduction rate and the volume reduction rate. The weight reduction rates of chaff mixtures were higher than those of sawdust mixtures, but the volume reduction rates of sawdust mixtures were more higher than those of chaff mixtures. Salinity increased as composting reaction proceeded, due to reduction in mass weight. The final salinity of Control was 2.79%, and the final range of salinities of chaff and sawdust mixtures were 2.18∼2.37% and 1.86∼2.05%, respectively.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.406-409
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• 2005

Since 2003, Korean government has restricted landfill application of organic waste, which shares approximately 56% of total waste sludge from municipal and industrial wastewater treatment plants. In addition, enforcement of the ocean disposal prohibition law is effective from 2005. Organic sludge was composted for the purpose of converting to organic fertilizer. After moisture content was regulated with bulking agents aerobic treatment performed. When composting was conducted, commercial and activated microbe materials, identified from soil were seeded in sewage sludge. Carbon dioxide production was increased sharply after 24 hours. Temperature and pH of compost reached to $66.2^{\circ}C$ and 8. Heavy metals were lower than their regulatory limits, which enable it to utilize as organic fertilizer.