• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.66-70
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• 1997

A mixed-culture of Gluconobacter suboxydans IFO 3172 and Saccharomyces uvarum IFO 0751 was per-formed in a synthetic medium. the optimal inculum ratio of G. suboydans and S. uvarum for mixed-culture fermentation was 150:1. The optimum pH, incubation temperature and aeration rate for mixed-culture fer- mentation were 5.0, 3$0^{\circ}C$ and 2.25vvm, reapectively. As a result of batch pure-and mixed-culture fer-mentation, specific growth rate in pure-culture of both strain was lower than that in mixed-culture. The yield of cell mass from S. uvarum exclusively decreased. The growth rate of the mixed-culture was very similar to the pure-culture in the begining of culture, but it has been decreased after 16hrs. In the mean time, S. uvarum in mixed-culture fermentation could grow due to fructose converted, but it could not row in pure-culture fermentation. Thus, the relationship was a sort of commensalism. The kinetic parameters cal-culated through steady-state results during continuous fermentations are as follows :{TEX}$$\mu$_{max1}${/TEX}=0.118({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{1}${/TEX}=0.330(g/L),:{TEX}$$\mu$_{max2}${/TEX}=0.162({TEX}$h^{-1}${/TEX}), {TEX}$Ks_{2}${/TEX}=0.038(g/L). The yield of bacterial cell mass relatively constant, but yield of yest cell mass was gradually decreased.

• Journal of environmental and Sanitary engineering
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• v.24 no.1
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• pp.13-24
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• 2009

This study was performed to determine the effect of the influent flow distribution ratio and hydraulic retention time(HRT) on removal of organic matter, nitrogen and phosphorus when domestic sewage was treated by the advanced step aeration(ASA) process. Results of the experiment for the determination of the optimum influent flow distribution ratio between the anaerobic reactor and the anoxic reactor showed BOD removal efficiencies of above 92.0% at all influent flow distribution ratios from 9:1 to 4:6. The highest T-N removal efficiency was 82.6% at the influent flow distribution ratio of 6:4. On the other hand, the highest T-P removal efficiency was 67.8% at the influent flow distribution ratio of 9:1. Considering both the T-N and T-P removal efficiencies, the influent distribution ratio of 6:4 was considered the optimum. Results of the experiment for the determination of the optimum HRT at the optimum influent flow distribution ratio of 6:4 revealed BOD removal efficiencies better than 92.7% at all HRTs from 12hr down to 6hr. The highest T-N and T-P removal efficiency were 82.6% and 59.5%, respectively both at the HRT of 8hr. In conclusion, the optimum influent flow distribution ratio and HRT for treatment of domestic sewage by the ASA process were determined to be 6:4 and 8hr, respectively.

• Journal of Environmental Science International
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• v.25 no.11
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• pp.1493-1498
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• 2016

The efficiencies of Gang-Byeon sewage treatment facilities, which are based on GPS-X modelling, were analysed and used to design recycle water treatment processes. The effluent of an aeration tank contained total kjeldahl nitrogen (TKN) of 1.8 mg/L with both C-1 and C-2 conditions, confirming that most ammonia nitrogen ($NH_3{^+}-N$) was converted to nitrate nitrogen ($NO_3{^-}-N$). The concentrations of $NH_3{^+}-N$ and $NO_3{^-}-N$ were found to be 222.5 and 227.2 mg/L, respectively, with C-1 conditions and 212.2 and 80.4 mg/L with C-2 conditions. Although C-2 conditions with higher organic matter yielded a slightly higher nitrogen removal efficiency, sufficient denitrification was not observed to meet the discharge standards. For the total nitrogen (T-N) removal efficiency, the final effluent concentrations of T-N were 293.8 mg/L with biochemical oxygen demand (BOD) of 2,500 mg/L, being about 1.5 times lower than that (445.3 mg/L) with BOD of 2,000 mg/L. Therefore, an external carbon source to increase the C/N ratio was required to get sufficient denitrification. During the winter period with temperature less than $10^{\circ}C$, the denitrification efficiency was dropped rapidly even with a high TKN concentration (1,500 mg/L). This indicates that unit reactors (anoxic/aerobic tanks) for winter need to be installed to increase the hydraulic retention time. Thus, to enhance nitrification and denitrification efficiencies, flexible operations with seasons are recommended for nitrification/anoxic/denitrification tanks.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.4
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• pp.497-505
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• 2005

Domestic Sewage Treatment Plants are mostly based on biological treatment, in which large amounts of excess sludge are generated and occupy about 40 ~ 60% of the total sewage treatment costs. Several methods for sludge treatment has been so far reported as upgrading biodegradation of sludge; heat treatment, chemical treatment, including thermo-alkali and ozone, mechanical treatment including ultrasonic pulverization. But, it has a limitation in case of reducing the amount of excess sludge which are already producted. In this study, application of excess sludge reduction process using thermophilic aerobic bacteria for activated sludge was examined. The research was carried out two different stage. one for a biological wastewater treatment and the other for a thermophilic aerobic solubilization of the waste sludge. A portion of excess sludge from the wastewater treatment step was into the thermophilic aerobic sludge solubilization reactor, in which the injected sludge was solubilized by thermophilic aerobic bacteria. The solubilized sludge was returned to the aeration tank in the wastewater treatment step for its further degradation. Sludge solubilization reactor was operated at $63{\pm}2^{\circ}C$ with hydraulic retention time(HRT) of 1.5 ~ 1.7 day. Control group was operated with activated sludge process(AS) and experiment group was operated with three conditions(RUN 1, RUN 2, RUN3). RUN 1 was operated with AS without sludge solubilization reactor. RUN 2 were operated with AS with sludge solubilization reactor to examine correlation between sludge circulation ratio and sludge reduction ratio by setting up sludge circulation ratio to 3. RUN 3 was operated with sludge circulation ratio of 3 and MLSS concentration of 1,700~2,000mg/L to examine optimum operation condition. The quantity of excess sludge production was reduced sharply and in operation of RUN 3, sludge The quantity of excess sludge production was reduced sharply and in operation of RUN 3, sludge solubilization ratio and sludge reduction ratio were 53. 7%, 95.2% respectively. After steady state operation, average concentration of TBOD, SBOD, $TCOD_{Cr}$, $SCOD_{Cr}$, TSS, VSS, T-N, T-P of effluent were 4.5, 1.7, 27 .8, 13.8, 8.1, 6.2, 15.1, 1.8mg/L in the control group and were 5.6, 2.0, 28.6, 19.1, 9.7, 7.2, 16.1, 2.0mg/L in the experimental group respectively. They were appropriate to effluent standard of Sewage Treatment Plants.

• Journal of Korean Society on Water Environment
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• v.20 no.1
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• pp.18-23
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• 2004

In this research, a 2-stage intermittently aerated activated sludge system(IA) and intermittently aerated dynamic flow activated sludge system(DF) were investigated for the removal of nutrients in domestic wastewater. Wastewater was characterized by low C/N( organics/nitrogen) ratio. $COD_{cr}$, $BOD_s$, TKN and TP concentrations of domestic wastewater were 235, 47, 32 and 5.4 mg/L, respectively. Three sets of IA and one set of DF were operated. Three of four systems were added with fermented settled sludge taken from primary settling tank as an external electron donor and the other(IA) for control reactor was operated without addition of electron donor. All systems were operated at same sludge retention time of 20 days and hydraulic retention time of 12hrs. The supplemental electron donor was supplied into the anoxic mode. A higher denitrification rate was observed from the reactors with fermented settled sludge as an electron donor for denitrification compared to that of without addition of organic source. The result of this study indicates that the settled primary sludge, if the fermented at the acid stage, was an excellent electron donor for denitrification. 81 % of TN and 80% of TP were removed from the systems with the supplemental organic source added. However, the control reactor without addition of electron donor showed only 39% of TN and 43% of TP.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.120-131
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• 1998

This study was performed to define the physicochemical characteristics of food waste and food wastewater, and to find the effect of moisture content variation and salinity variation on aerobic composting for food wastes. In moisture content variation experiment, the samples of 2-1, 2-2, 2-3 and 24 were prepared by the moisture content of 83.8%, 70.9%, 64.8% and 45.1%, respectively. In salinity variation experiment, the samples of 3-1, 3-2, 3-3 and 3-4 were prepared by the salinity of 0.99%, 1. 69%, 1.75% and 2.34%, respectively. In both experiments, aerobic composting reactors were operated by the mode which was composed of half an hour's stirring and 2 hour's aeration per day, for 45 days. The followings are the conclusions that were derived from this study. 1. In the study of physicochemical characteristics of food waste and food wastewater, the values of pH were 4.19 and 3.96, the values of salinity were 0.91% and 1.17%, and the values of conductivity were 7.6 mS/cm and 18.2 mS/cm, respectively. 2. In food waste, the moisture content was 60.3%, organic compound content was 96.1%, total carbon was 48.0%, total nitrogen was 1.5%(therefore, C/N ratio was 32), and the concentration of total phosphorus was 1.34 mg/kg. 3. The time of temperature ascending was delayed, the highest temperature was lowered, the duration period of high temperature was shortened by the increasing of moisture content. In the higher moisture content, anaerobic condition was formed, bad smell was released, insects were gathered and multiplicated, and the reaction rate of composting was reduced. 4. In moisture content experiment, C/N ratios were changed from the range of 31.2-34.8 at the beginning phase to that of 20.4-28.4 at the last phase. 5. In salinity experiment, the reduction rate of volume was increased(40.3%) when the salinity was decreased(0.99%). Also, the reduction rate of mass was increased(51.8%) when the salinity was decreased(0.99%). This fact denotes that salinity hinders the process of composting. 6. the concentrations of total nitrogen and total phosphorus were increased from 0.74% to 1.10%, and from 0.82 mg/kg to 3.44 mg/kg, respectively when the salinity was decreased from 2.34% to 0.99%.

• Korean Journal of Food Science and Technology
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• v.17 no.1
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• pp.25-32
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• 1985

Low-temperature in-bin paddy drying has been examined to study the limitations of this drying method under Korean weather conditions, the initial moisture content of the paddy, the bulk depth and the airflow rate. The results are reported and discussed with regard to drying time, energy requirements and costs, uniformity in the moisture content of the dried kernels and, finally, the quality of the paddy. The tests carried out during the paddy-drying period in 1981 and 1982 have shown that under Korean weather conditions paddy can be dried to safe storage conditions by continuous aeration with ambient air. Depending upon the initial moisture content of the kernels(19.2%-25.5% w.b.), the bulk depth(1.1-3.5m) and the airflow $(3.0-6.9m^3\;air/m^3\;paddy/min)$ the paddy could be dried within 5 to 17 days. The energy requirements and energy costs are shown to be considerably lower than for conventional high-temperature drying. No significant changes in the quality in terms of milling yield, cracking ratio, acid value and germination were observed.

• Journal of Animal Science and Technology
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• v.45 no.4
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• pp.641-648
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• 2003

In a batch mode treatment process, which electrolyzes the wastewater after derivation of N-P crystal formation and recovery, the characteristics of pollutant removal induced with the changes of loading rate and hydraulic retention time were studied. $MgCl_2$ was used as Mg source for the formation of struvite and the molar ratio of $MgCl_2$ to $PO_4^{3-}$ in influent was 1.3. When analyzing the average treatment efficiencies and removal characteristics obtained from four separate operations (Run I, II, III, IV), removal efficiencies of PO43- was not function of its loading rate. Under a condition of sufficient aeration and Mg source provided, over 88% of $PO_4^{3-}$ was eliminated by the formation of MAP without any pH adjustment, in spite of loading rate variation. An optimum-loading rate of NH4-N to achieve high removal efficiency was approximately $100g/m^3/d$. Below that loading rate, the removal of NH4-N was proportional to the loading rate into the system, and hence stable and high removal efficiency, over 90%, was achieved. However, when the loading rate increased over that rate, removal efficiency began to drop and fluctuate. Removal efficiency of TOCs was dependant upon the hydraulic retention time ($r^2$=0.97), not upon the loading rate. Stable and high color removal (94%) was obtained with 2 days of HRT in electrolysis reactor.

• Journal of the Korea Organic Resources Recycling Association
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• v.11 no.1
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• pp.149-153
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• 2003

This study was conducted to survey the utilization possibility of composting system of small scale static pile with animal manure produced from cattle shed and the effect of addition of microorganism on the maturity of compost. Microorganisms added in composting substrate were bacteria+lactobacillus(BL)+photo.(BLP). The composting practiced was a windrow system without aeration equipment and turning was practiced periodically. The water content of substrate mixed with cow manure, rice husk, and sawdust was about 60%. The temperature during the composting process was increased at over $60^{\circ}C$ within 3 days after composting starting. Increase of temperature at the early stage of composting was fasten in BLP and BL than Control. Because the pH of the raw material was high, the changes of pH during composting was little and stabilized in weak alkaline condition. EC value was high for accumulation of manure and urine excreted continuously by animal and the changes of those during composting occurred in 5~10% increase. Reduction rates of C/N ratio were the largest as the 22.7% in BLP and 19.2and 17.5% in BL and Control respectively. In the evaluation of phytotoxicity, there was stabilized within the short time in BLP and not the difference between BL and Control. Treatment of animal manure produced from small scale cattle shed was possible by using the small scale static pile composting system with reasonable water content and turning and the addition of microorganism in composting substrate was effected on the temperature increase at the early stage of composting and reduction of plant toxicity compounds but little on the maturity of compost.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.63-74
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• 2016

The objective of this study was to investigate the variations of physico-chemical properties during the swine manure composting, sawdust as the bulking agent was composted at different points (Top layer, Side of middle layer, Bottom layer). Air suction system with constant bottom aeration in bench scale reactors (30 L). The highest temperature was reached in the range of $58^{\circ}C$ to $62^{\circ}C$ on $3^{rd}$ day and this thermophilic phase (> $50^{\circ}C$) was continued for 3 days in all the treatment mixtures. However, the temperature was gradually decreased to room temperature at the end of 60 day composting process. Except control, the discharged ammonia ($NH_3$) was a maximum in the treatment order of Top layer>Bottom layer>Side of middle layer as 500 ppm, 162 ppm and 120 ppm, respectively, on the $4^{th}$ day and showing that Top layer point Air suction produce much more ammonia content than the other point. During the composting process, the total Kjeldahl nitrogen (TKN) was gradually increased due to the mass loss in the composting mixtures. At the same time, C/N ratio was decreased to Top layer, 13; Side of middle layer, 12 and Bottom layer, 13 at Air suction points. The significant reduction of C/N ratio in all different air suction system when manure was matured. The $NH_4-N$ to $NO_3-N$ ratio was recorded as 10.52 at the initial stage of the compost mixtures and reduced to 0.97 (Top layer), 0.70 (Side of middle layer), 3.2 (Bottom layer) because of manure decomposition. The overall results revealed that Top layer and Side of middle layer Air suction is a suitable option when compared other point for high quality composts.