• KSBB Journal
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• v.9 no.4
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• pp.365-371
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• 1994

The effects of ratios of initial concentration of carbon source to the initial concentration of nitrogen source in the fermentation media on both the yields of PHB fermentation variables and the accumulation of poly-${\beta}$-hydroxybutyric acid(PHB) were investigated. The fermentation media were composed of the combination of varing glucose concentrations, 10, 20, 25, 30, 40, $50g/\ell$ and the NH4Cl concentrations 0.33, 0.4, 0.5, 1.5, 3, $5g/\ell$. The yield of biomass on glucos, Yx/s, decreased very slowly according to the increase of the ratio of C to N. And the yield became constant at 0.35(g biomass/g glucose) with the ratio higher than 70. The yield of residual biomass, Yx/s, also decreased with the ratio of C to N and finally showed a constant value of 0.065(g residual biomass/g glucose) when the ratio was higher than 65. In accordance with the augmentation of the ratio, the yield of PHB, YPHB/S, however, increased and showed the maximum value of 0.35 (g PHB/g glucose) between 40 and 60 of the ratio. The maximum yield of PHB to the change of biomass, YPHB/S, was 0.87(g PHB/g biomass), and the yie1d YPHB/RX, was 4.2(g PHB/g residual biomass). The maximum accumulation percent of PHB to the final biomass was 81% when the ratio was higher than 67.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.499-506
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• 2005

This study was performed to investigate the effects of influent C/N ratio on the removal of organic and nitrogenous compounds by two nonwoven fabric filter bioreactors. The reactors were alternately aerated at an aeration/nonaeration period ratio of 60 min/60 min, and fed with wastewater only during nonaeration period. The influent C/N ratio (COD/TKN) was gradually reduced from 10 to 2. The influent was prepared by diluting the leachate from a foodwaste treatment facility in I city so that the COD concentration could be about 2,500 mg/L. The C/N ratio of the wastewater was adjusted by adding ammonium chloride. The results of the experiment showed that the COD and BOD concentration of the effluent was $40{\sim}54\;mg/L$ and $1{\sim}4\;mg/L$, respectively at the C/N ratios of $10{\sim}3$, and the effluent SS concentration was always below 2.0 mg/L. The T-N removal efficiencies were 96% or higher at C/N ratios of $10{\sim}5$, but decreased to 83% and 81%, respectively at the C/N ratios of 3 and 2.8. At the C/N ratios of 2.6 and 2, the effluent quality deteriorated due to ammonia toxicity. The fraction of nitrifying microorganism in the reactors increased from 10% to 20% as the C/N ratio decreased from 5 to 2.6. Alkalinity consumed were $3.12{\sim}3.49\;g$ alkalinity/g T-N removed at the C/N ratios of $10{\sim}5$, which are lower than the theoretical value of 3.57. However, the ratio increased to 4.63 and 4.87 g alkalinity/g T-N removed, respectively at the C/N ratios of 3 and 2.8.

• Journal of the Korea Organic Resources Recycling Association
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• v.7 no.2
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• pp.105-111
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• 1999

This study was performed about composting in a batch reactor of laboratory scale using garbage waste and swine waste. Sawdust and coconut peat were materials to control optimum moisture, C/N ratio and specific gravity in the study. Comparing compost using only sawdust with compost using sawdust and coconut peat, the latter was higher at reduction rate and decomposition rate. Coconut peat was accelerated aerobic fermentation, because it had moisture holding ability, initial moisture was low, ventilation was good and control of optimum specific gravity was possible. Compost by only garbage waste was under standard of manure. but mixtures in same proportion of garbage waste and swine waste producted high quality compost. CEC value was average 63.8me/100g. The initial C/N ratio of compost was regulated effectively because of high C/N ratio of sawdust. As the C/N ratio(>40) was higher, reduction rate was higher. During the composting C/N ratio was improved more and more.

• Journal of The Korea Institute of Healthcare Architecture
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• v.16 no.4
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• pp.33-40
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• 2010

Gross-to-net ratio is the important factor determining size of the building. However it was determined as the empirical method without the exact basis in the existing planning. This paper proposes more accurate methods for determining the gross-to-net ratio of architectural planning in general hospital. This paper analyzes the difference of gross-to-net ratio according to the various conditions and presents the elements of influencing on gross-to-net ratio. These elements is evaluated by applying in the typical hospital case. In conclusion, gross-to-net ratio is influenced by the accuracy of the space program, form type of the space and correspondence potential about the internal variation. In addition, This study has proved that empirical approach is a standard of minimum area.

• Journal of the Korea Organic Resources Recycling Association
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• v.2 no.1
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• pp.75-86
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• 1994

Garbage composting was studied in a controlled batch reactor with the addition of cooked rice as a biodegradable carbon source to find the effect of C/N ratio control on composting. And composting of bulking agents such as sawdust and wheat straw were tested with the addition of ammonium sulfate as a nitrogen source. As expected, biodegradation of the garbage having low C/N ratio was improved to some extent when foreign carbon was added. But bulking agents used in this study exerted slightly biodegradable carbon potential, indicating that the estimation of the dose of additional carbon considering desirable C/N ratio was not reasonable when lignocellulosic bulking material was added to garbage. It was found that the optimum moisture content increased with sawdust addition meaning the C/N ratio increment. Considering the above results, it was suggested that 78g sawdust per 100g garbage should be mixed to make C/N ratio to 25 and moisture content to 56% for effective composting of the garbage studied in this paper.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.355-361
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• 2006

In this study, effects of influent C/N(COD/Nitrate) ratio and dissolved oxygen(DO) concentration on biological nitrate removal from groundwater were investigated in the fixed-type biofilter. Influent nitrate of 30 mg/L was removed completely by biological denitrification at the C/N ratio of 10 and 4.0, while residual nitrate of 5 mg/L occurred at the C/N ratio of 2.0, which resulted from deficiency of organic electron donor. Furthermore, nitrite was accumulated up to about 5 mg/L as the C/N ratio decreased to 2.0. Increase in DO concentration also inhibited denitrification activity at the relatively high C/N ratio of 5.0, which decreased the nitrate removal efficiency. Although the influent DO concentration was reduced as low as 0.3 mg/L using sodium sulfite($Na_2SO_3$), effluent nitrite was up to 3.6 mg/L. On the other hand, nitrate was completely removed without detection of nitrite at the DO concentration of 0.3 mg/L using nitrogen gas($N_2$) sparging. The organic matter for denitrification in biofilter were in the range from 3.0 to $3.5gSCOD/g{NO_3}^--N$, while utilized these values increased at the high DO concentration of 5.5 mg/L. In addition to the high DO concentration and the low influent C/N ratio, DO control by chemical such as sodium sulfite affected on biological denitrification, which resulted in the reduction of nitrate removal efficiency and nitrite build-up in a biofilter.

• Korean Journal of Food Science and Technology
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• v.23 no.2
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• pp.167-174
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• 1991

Cultural conditions for the biopolymer production by an alkali tolerant Bacillus sp. isolated from soil were investigated and determination of optimal conditions was carried out by response surface method. The maximal production of biopolymer was obtained after cultivation at $30^{\circ}C$ for 36hrs in the mixture of 8% soluble starch, 0.75% yeast extract, 0.1% $NaNO_3$, 0.05% $MgSO_4\;7H_2O$ and 1% $Na_2CO_3$ adjusted to pH 10. Under these conditions, about 44 g/l of biopolymer were produced. From the results of response surface analysis, optimal condition for the production of biopolymer were obtained at stationary point with 15.16 of C/N ratio, $34.62^{\circ}C$ of temperature and 9.50 of pH. On the basis of these conditions, it was estimated that 66.84 g/l of the biopolymer could be produced.

• Korean Journal of Soil Science and Fertilizer
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• v.6 no.4
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• pp.227-230
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• 1973

To elucidate the effect of the organic carbon compounds included in a separate from glutamic acid fermentation residue (G. A. F. R) on the improvement of the physico-chemical properties of soil, on a soil low in organic matter content, treated with G. A. F. R and compost, observations on the total organic matter, humic acid, fulvic acid, C. E. C. and the development of aggregates were made. From the results of the investigations it was concluded that, the organic carbon compound in the tested G. A. R. F. is more effective than compost in increasing the total organic matter, humic acid, fulvic acid and C. E. C. of soil and in enhancing the development of soil aggregates.

• Korean Journal of Food Science and Technology
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• v.15 no.1
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• pp.56-61
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• 1983

Direct production of biomass from starch using amylolytic yeast, Sporobolomyces holsaticus FRI Y-5 was studied with varying the ratios between carbon and other nutrient sources in the medium. It was investigated under condition of constant C/P and C/S ratio to influence the initial concentration of starch $(S_o)$ and C/N ratio on its growth which is described as the specific growth rate $({\mu})$, cell yield (Y), the maximum concentration of cell $(X_m)$, and productivity (P). They were very dependent on both $S_o$ and C/N ratio. The form of the relationship between and ${\mu}$ and $S_o$ was observed to be similar to saturation kinetics at C/N = 100 but presented substrate inhibition at other C/N ratios. As $S_o$ was changed from 22.5 to 90 g/l, Y was observed to vary with C/N ratios but seemed to decrease as a wholes. $X_m$ was linearly related to $S_o$ at more than C/N = 50 but at less than C/N = 10 substrate inhibition was presented. P increased suddenly to $S_o$ = 45 g/l and then changed decreasingly at less than C/N = 50, but at more than C/N = 100 it changed increasingly. The effect of C/P ratio and C/S ratio on the yeast growth was also investigated at constant $S_o$ and C/N ratio. ${\mu}$ was dependent on C/P and C/S ratios, but Y, independent on them. But $X_m$ was reliant upon C/P ratio but not upon C/S ratio.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.6
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• pp.628-636
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• 2008

Anaerobic denitrification in a two phase anaerobic digestion(TPAD) process combined with biological nutrients removal (BNR) system was studied for a piggery wastewater treatment. Denitrification efficiency and the effects of the nitrified effluent on acidification was investigated by recycling the nitrified effluent to the acidogenic reactor. Recycle of the nitrified effluent to the acidogenic reactor enhanced the conversion efficiency of the influent COD into volatile fatty acids(VFAs) in the TPAD-BNR system treating the piggery wastewater. Acidification rate of the acidogenic sludge acclimated with the nitrified effluent showed 6 times higher than that acclimated without it. VFA could be used for denitrification as carbon sources, however, nitrate could enhance acidification activity in the acidogenic reactor. VFA production rate was affected on the COD/Nitrate(COD/N) ratio, however, it depended much more whether the acidogenic sludge acclimated with nitrate or not. Denitrification with the acidogenic sludge acclimated without nitrified effluent followed zero-order reaction and the reaction rate constants were in the range of 1.31$\sim$1.90 mg/L$\cdot$h. Denitrification reaction rate constants of the acidogenic sludge acclimated with nitrified effluent were 3.30 mg/L$\cdot$h that showed almost twice of them evaluated from the previous tests. The stoichiometric ratios of utilized COD to removed nitrate showed similar in both tests which were in the range of 5.1$\sim$6.4 at COD/N ratio of 10.