• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.781-788
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• 2008

This study shows how to find out optimum co-substrate conditions and continuous operating parameters for maximum acidification of three different organic wastes - livestock wastewater, sewage sludge and food waste. Design of experiments and statistical analysis were revealed as appropriate optimization schemes in this study. Analyses of data obtained from batch tests demonstrated the optimum substrate mixing ratio, which was determined by maximum total volatile fatty acids(TVFA) increase and soluble chemical oxygen demand(SCOD) increase simultaneously. Suggested optimum mixing ratio of livestock wastewater, sewage sludge and food waste was 0.4 : 1.0 : 1.1 based on COD, respectively. Response surface methodology(RSM) contributed to find out optimum operating parameter - hydraulic retention time(HRT) and substrate concentration - for the semi-continuous acidogenic fermentation of mixed organic wastes. The optimum condition for maximum TVFA increase was 2 days of HRT and 29,237 mg COD/L. Empirical equations obtained through regression analysis could predict that TVFA increase would be 73%. To confirm the validity of the statistical experimental strategies, a confirmation experiment was conducted under the obtained optimum conditions, and relative error between theoretical and experimental results was within 4%. This result reflects that using statistical and RSM technique can be effectively used for the optimization of real waste treatment processes.

• Journal of Practical Agriculture & Fisheries Research
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• v.11 no.1
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• pp.159-171
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• 2009

Required total substrates amounts for mushroom production are 212,186M/T in Korea. 80% of these total substrates amounts, 169,748 M/T is used for main substrates. Also 20%of these total substrates amounts, 42,438 M/T is used for additives. Main substrates 169,748 M/T is composed of sawdust, waste cotton, cotton seed hull, straw and com cob etc.. Additives 42,438 M/T is composed of rice bran, wheat bran and beet pulp etc. In the mushroom management, the cost of substrates purchase is composed for the most of management. Substrates amount is limited to supply, and the demand of mushroom substrates is on the increase continuously. So there is nothing but the cost of substrates are raising. Therefore the most important thing must develop the cheap substrates for the mushroom production.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.306-310
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• 2008

Characteristics of microalgal growth was investigated using anaerobic effluent from two-phase animal waste digestor as substrate. Batch experiments were carried out to investigate the effect of the initial nitrogen and phosphorus concentrations on growth of Microcystis aeruginosa, Chlorella sp. and Euglena gracilis. In 400 times diluted anaerobic effluent (TN 3 mg/L), single cell growth of the Euglena gracilis population increased twice without delay, although Chlorella sp. and Microcystis aerugenos take over 144 hours. Similar appearance with single cell growth was observed in mixed cultures. However, microalgae population did not increase under condition of 10 times diluted influent (TP 3 mg/L) in both pure and mixed cultures, which was affected by high organic and nitrogen concentration. Logistic growth model successfully fitted to determine biokinetic parameters such as ${\lambda}$: lag time, ${\mu}m$: maximal specific growth rate, A: asymptote of growth.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.18 no.3
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• pp.363-372
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• 2020

Anionic radionuclides pose one of the highest risks to the long-term safety assessments of disposal repositories. Therefore, techniques to immobilize and separate such anionic radionuclides are of crucial importance from the viewpoints of safety and waste volume reduction. The main objective of this study is to design a separator with minimum pressure disturbance, based on the concept of a conventional cyclone separator. We hypothesize that the anionic radionuclides can be immobilized onto a nanomaterial-based substrate and that the particles generated in the process can flow via water. These particles are denser than water; hence, they can be trapped within the cyclone-type separator because of its design. We conducted particle tracking analysis using computational fluid dynamics (CFD) for the conventional cyclone separator and studied the effects due to the morphology of the separator. The proposed sandglass-like design of the separator shows promising results (i.e., only one out of 10,000 particles escaped to the outlet from the separation zone). To validate the design, we manufactured a laboratory-scale prototype separator and tested it for iron particles; the efficiency was ca. 99%. Furthermore, using an additional magnetic effect with the separator, we could effectively separate particles with ~100% efficiency. The proposed sandglass-like separator can thus be used for effective separation and recovery of immobilized anionic radionuclides.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.3
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• pp.333-339
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• 2011

In the present work, it was attempted to produce $H_2$ from food waste by the two-stage fermentation system. Food waste was acidified to lactate by using indigenous lactic acid bacteria under mesophilic condition, and the lactate fermentation effluent (LFE) was subsequently converted to $H_2$ by photo-fermentation. $Rhodobacter$ $sphaeroides$ KD131 was used as the photo-fermenting bacteria. The optimal conditions for lactate fermentation were found to be pH of 5.5 and substrate concentration of 30 g Carbo. COD/L, under which yielded 1.6 mol lactate/mol glucose. By filtering the LFE and adding trace metal, $H_2$ production increased by more than three times compared to using raw LFE, and finally reached the $H_2$ yield of 3.6 mol $H_2$/mol lactate. Via the developed two-stage fermentation system $H_2$ yield of 5.8 mol $H_2$/mol glucose was achieved from food waste, whose value was the highest that ever recorded.

• Journal of the Korea Organic Resources Recycling Association
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• v.5 no.2
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• pp.7-16
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• 1997

The food waste composting facility of 10 ton/d capacity at Nanjido has been operated successfully since July, 1996. This study was performed to investigate the characteristics of food waste quality, and variation of physicochemical characteristics of feed materials during composting. Food waste with 79% moisture content was used as a substrate. Wood chip was used as a bulking agent. Monitoring results based on VS, TOC, C/N ratio and gas composition indicated that the facility was operated normally under aerobic conditions. Conductivity values during food waste composting were increased. A highly positive correlation (r=1.00) existed between VS and TOC.

• Journal of Microbiology and Biotechnology
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• v.18 no.8
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• pp.1408-1415
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• 2008

To produce polyhydroxyalkanoate (PHA) from inexpensive substrates by bacteria, vegetable-oil-degrading bacteria were isolated from a rice field using enrichment cultivation. The isolated Pseudomonas sp. strain DR2 showed clear orange or red spots of accumulated PHA granules when grown on phosphate and nitrogen limited medium containing vegetable oil as the sole carbon source and stained with Nile blue A. Up to 37.34% (w/w) of intracellular PHA was produced from corn oil, which consisted of three major 3-hydroxyalkanoates; octanoic (C8:0, 37.75% of the total 3-hydroxyalkanoate content of PHA), decanoic (C10:0, 36.74%), and dodecanoic (C12:0, 11.36%). Pseudomonas sp. strain DR2 accumulated up to 23.52% (w/w) of $PHA_{MCL}$ from waste vegetable oil. The proportion of 3-hydroxyalkanoate of the waste vegetable-oil-derived PHA [hexanoic (5.86%), octanoic (45.67%), decanoic (34.88%), tetradecanoic (8.35%), and hexadecanoic (5.24%)] showed a composition ratio different from that of the corn-oil-derived PHA. Strain DR2 used three major fatty acids in the same ratio, and linoleic acid was the major source of PHA production. Interestingly, the production of PHA in Pseudomonas sp. strain DR2 could not occur in either acetate- or butyrate-amended media. Pseudomonas sp. strain DR2 accumulated a greater amount of PHA than other well-studied strains (Chromobacterium violaceum and Ralstonia eutropha H16) when grown on vegetable oil. The data showed that Pseudomonas sp. strain DR2 was capable of producing PHA from waste vegetable oil.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.3
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• pp.199-205
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• 2015

Organic wastes such as food waste (FW), livestock wastewater (LW), and sewage sludge (SWS) can produce hydrogen ($H_2$) by anaerobic acid fermentation. Expecially, FW which has high carbohydrate content produces $H_2$ and short chain fatty acids by indigenous $H_2$ producing microorganisms without adding inoculum, however $H_2$ production rate (HPR) and yield have to be improved to use a commercially available technology. In this study, LW was mixed to FW in different ratios (on chemical oxygen demand (COD) basis) as an auxiliary substrate. The mixture of FW and LW was pretreated at pH 2 using 6 N HCl for 12 h and then fermented at $37^{\circ}C$ for 28 h. HPR of FW, 254 mL $H_2/L/h$, was increased with the addition of LW, however, mixing ratio of LW to FW was reversely related to HPR, exhibiting HPR of 737, 733, 599, and 389 mL $H_2/L/h$ at the ratio of FW:LW=10:1, 10:2, 10:3, and 10:4 on COD basis, respectively. Maximum HPR and $H_2$ production yield of 737 $H_2/L/h$ and 1.74 mol $H_2/mol$ hexoseadded were obtained respectively at the ratio of FW:LW=10:1. Butyrate was the main organic acid produced and propionate was not detected throughout the experiment.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.3
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• pp.126-131
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• 2002

For the probiotic feed production from residual food waste, aerobic liquid fermentation was conducted by thermophilic bacteria. 11 Strains of bacteria were isolated from several soil sources and residual food waste. Screening was carried by shaking incubator for the separation of thermophilic strain at $55^{\circ}C$. The isolated strains were tested for enzyme activities such as ${\alpha}$-amylase and protease. 6 Bacterial strains were chosen and were adapted by repeated fermentation processes in food waste substrate. The viable cell count of them at final fermentation stages were shown as $3-7{\times}10^9/ml$ in 2L-jar fermenter. Among them B3, B6 showed higher enzyme activity. By the mixed fermentation of B3, B6 and Bacillus stearothermophilus, the highest viable cell count reached to $1.4{\times}10^{10}/ml$ in 8 hours.

• The Korean Journal of Mycology
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• v.20 no.4
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• pp.354-359
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• 1992

The effect of the addition of various vegetable oils on the mycelial growth was studied. Most vegetable oils were proved to be stimulative for the mycelial growth, and the best mycelial growth (12 mg/ml) was obtained with the addition of cotton seed oil. Several agricultural wastes i.e., rice straw, peanut hull, sawdust, rice hull, cocoa hull, coffee waste and beer waste were empolyed as substrates for sporophore production of p. sajor-caju. The biological efficiency(BE) for sporophore productions of rice straw and peanut hull were 36.4% and 32.6%, respectively. The highest yield of sporophore was obtained from the mixture of rice straw (50%) and beer waste (50%)(BE 109.6%) followed by peanut hull (50%) and beer waste (50%)(BE; 74.5%).