• Microbiology and Biotechnology Letters
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• v.28 no.6
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• pp.361-366
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• 2000

Genera and number of protozoa were investigated in the conventional activated sludge pilot plant used for the treatment of municipal sewage and pre-treated night soil-containing sewage. In both case, the predominant protozoa was ciliates and among them Vorticella was the most common. In the pilot plant where pre-treated night soil was mixed with municipal sewage, genera of free-swimming ciliates, flagellates and amoeba was higher than in those withour night soil. Correlation analysis on the quality of effluent and protozoa indicates that municipal sewage has positive correlation with protozoa. However in the pilot plan 샐 sewage contatinin pre-treated night coil soil more samples show negative correlation. Followed equations were derived by the regression analysis of BOD in both the pilot plants. In case of pilot plant A of municipal sewage, the analysis B of munici-pal and pre-treated night soil-containing sewage, the analysis of BOD was $6.731$\times$10_{-2}$ $\times$Bodo+0.306(Adjusted $R^2$=0.864). At low temperature, number of protozoa was decreased to 35% and among therm, Aspidisca was the most common genus. Therefore, protozoa can be used as indicator of quality of the effluent in sewage treatment plants.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.756-760
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• 2007

Most of the sewage treatment plants in Korea are being operated by using the conventional activated sludge process. Recently, as the water criteria have been strict with regard to such main culprits of eutrophication, the existing sewage treatment plants are obliged to upgrade their treatment technology to meet the criteria. Under such circumstances, this study was aimed at analyzing the conditions of an existing sewage treatment plants in Korea, and thereupon, test its treatment performance for the actual sewage water by operating a pilot plant. When the pilot plant was operated with the NPR process at the capacity of $30m^3/day$, the average contents of BOD, $COD_{Mn}$, SS, T-N and T-P in the effluents were 7.0 mg/L, 9.7 mg/L, 5.1 mg/L, 8.0 mg/L and 0.23 mg/L, respectively, which were very stable in general. Accordingly, if the NPR process used for this pilot plant to upgrade the treatment technology for the sewage treatment plat could be adopted, the effluent water quality criteria effective beginning from 2008 would be met.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.117-120
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• 2006

The purpose of this study is to efficiently treat the sewage sludge discharged from sewage treatment plants and evaluate the feasibility of the manufacture of lightweight aggregates(LWA) using a large quantity of sewage sludge. Sintered lightweight aggregate from sewage sludge is experimentally manufactured with various mass ratios of clay to sewage sludge by a pilot plant, and is tested for density, water absorption and crushing value. Their physical properties are compared to those of a commercial sintered lightweight aggregate. As a result, an experimentally manufactured lightweight aggregate is similar or superior in physical properties to the commercial lightweight aggregate. The manufactured lightweight aggregate could be used for structural concrete and non-structural concrete.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1315-1322
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• 2010

A membrane bioreactor (MBR) was designed using polyvinylidene fluoride(PVDF)-type hollow fiber membrane modules with a treatment capacity of 10 ton/day. A pilot plant was installed in a sewage treatment plant and was operated with an intermittent aeration method which avoids any concentration gradient of suspended solids (SS) in the MBR. For continuous operation, the pilot plant was first tested with influent (mixed liquor suspended solid:MLSS of 1000-2000 mg/L) of aeration tanks in the sewage treatment plant. The MBR was pre-treated with washing water, 10% ethanol solution, 5% NaOCl solution and finally washing water, one after another. To demonstrate the effect of the MBR on sewage treatment, compared with conventional activated sludge processes, we investigated the relationships among permeate amount (LMH), change in operation conditions, influent MLSS level and sludge production. It was found that the optimum aeration rate and suction pressure were $0.3\;m^3$/min and 30~31 cmHg, respectively. Under stable conditions in aeration, suction pressure, influent flow rate and drainage, the SS removal efficiency was more than 99.99% even when the MLSS loading rate changes. Compared with conventional activated sludge processes, the MBR was more effective in cost reduction by 27% based on permeate amount and by 51.5% on sludge production.

• Environmental Engineering Research
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• v.14 no.3
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• pp.174-179
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• 2009

The InSub system(applied for a patent) was developed, as it combined the indirectly aerated submerged biofiltration(InSub) reactor and Anaerobic/ Anoxic reactor. This system which can eliminate organism and nutrient materials at the same time, which is safe and economical to be maintained and managed is more simple process than the complicated existing biological advanced sewage treatment system. The most suitable HRT of this study showed 9 hours. As looking into the effluent concentration and removal efficiency of each item at 9 hours of HRT, each effluent concentration for $SS,\;BOD5,\;COD_{Mn},\;and\;COD_{Cr}$ was 1.46 mg/L, 7,09 mg/L, 9.84 mg/L and 16.42 mg/L. And their removal efficiency was 96.98%. 90.59%, 77.18% and 83.92%, respectively. Each effluent concentration of T-N and T-P was 10.42 mg/L and 1.04 mg/L. Their removal efficiency was 73.38% and 61.62%, respectively. This pilot plant experiment(the state was without the internal recycling.) followed a variety of HRT. The results confirmed that it was to be advanced sewage treatment system with high efficiency when it combined with the internal recycling.

• Journal of Environmental Science International
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• v.13 no.9
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• pp.779-878
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• 2004

This study was conducted to analyze the operating conditions of predenitrification process to improve the treatment efficiency in low organic loading sewage plant in use today, and to investigate the treatment efficiency of pilot plant added night soil as well as the nitrogen removal characteristics of pilot plant added carbon sources. In the operation under the condition of $BOD_{5}$ sludge load 0.03-0.28kg $BOD_{5}$/kg VSS/d and oxic ammoniac nitrogen sludge load 0.02-0.24 $kgNH_{4}^{+}$-N/kg MLVSS/d, nitrification efficiency is higher than 95%. In order to achieve 70% nitrogen removal at the T-N sludge loading 0.06kg T-N/kg VSSㆍd and the SRT 6～11 days, optimum operating factors were revealed to $CODc_{r}$/T-N ratio 9, recycle ratio 2.6, and denitrification volume ratio 0.33. At this time, denitrification capacity was approximately 0.09 kg $NO_{3}^{-}$-N/kg $CODc_{r}$; specific nitrification rate was 3.4mg $NH_{4}^{+}$-N/g MLVSS/hr; and specific denitrification rate was 4.8mg $NO_{3}^{-}$-N/g MLVSS/hr.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.227-234
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• 2009

In this research, a retrofitting process, which consists of a pretreatment system (coagulation) for dye wastewater combined with a biological nutrient system (MLE process using media), for a sewage treatment plant that has to treat dye wastewater efficiently with domestic wastewater were developed and a pilot plant was operated for verifying adoptability and performance of the developed advanced process for dye wastewater. From the results of the pilot plant operation, BOD 52.9%, $COD_{Cr}$ 55.9%, and color 71.3% were removed in pretreatment of coagulation process and the biodegradability of dye wastewater was improved to $0.32{\sim}0.59BOD/COD_{Cr}$ of the coagulated wastewater from $0.29{\sim}0.43BOD/COD_{Cr}$ of the raw dye wastewater. The final effluent concentrations were BOD of 8 mg/L, $COD_{Cr}$ of 43 mg/L, $COD_{Mn}$ of 18 mg/L, T-N of 8 mg/L, and T-P of 1.3 mg/L, respectively. Color was removed from 1655 to 468 unit by coagulation and then to 123 unit by MLE process. The HPLC analysis of aromatic amines in wastewater showed that decolorization was achieved by cometabolism while aromatic amines were produced by cleavage of azo bonds under anaerobic conditions and these products were removed in an aerobic tank subsequently. Nitrification rates of attached and suspended microorganisms were evaluated comparatively and the acclimating conditions of bacteria on media were validated by the scanning electron microscope.

• Environmental Engineering Research
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• v.23 no.2
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• pp.195-204
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• 2018

A pilot scale study was conducted on a down-flow hanging sponge (DHS) reactor installed at a sewage treatment plant in Banda Aceh, Indonesia for treatment of desludging septic tank wastewater. Raw wastewater with an average biochemical oxygen demand (BOD) and total suspended solids of 139 mg/L and 191 mg/L, respectively, was pumped into the reactor. Two different hydraulic retention times (HRTs, 3 h and 4 h) were investigated, equivalent to organic loadings of 1.11 and $0.78kg\;BOD/m^3/d$, respectively. The average BOD concentration in the final effluent was 46 and 26 mg/L at HRTs of 3 and 4 h, respectively. The concentration of retained sludge along the reactor height was 10.2-18.7 g VSS/L-sponge, and the sludge activities were 0.24-0.32 and 0.04-0.40 mg/g VSS/h for heterotrophs and nitrification, respectively. Values of water hold-up volume, dispersion coefficient, and number of tank in-series found from tracer studies of clean sponge and biomass-loaded sponge confirmed that growth of retained sludge on the sponge module improved hydraulic performance of the reactor. Adoption of the DHS reactor by this Indonesian sewage treatment plant would enhance the role of the current desludging septic tank wastewater treatment system.

• Membrane Journal
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• v.12 no.3
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• pp.151-157
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• 2002

This research was to demonstrate the Possibility of sewage reuse for industrial purpose with use of membrane system. A bench scale test with microfiltration and reverse osmosis showed that microfiltration in the sewage treatment was not able to remove the soluble salts but 70% suspended solids (SS), suggesting that the treated water could be used as direct cooling water. In addition, the reverse osmosis removed not only soluble salts but also 95% SS, proposing that reverse osmosis-treated water could be used as both indirect cooling water and rinsing water. For a 100 ton/day pilot plant, 20 and 12 elements of microfiltration and reverse osmosis were required, respectively.

• Clean Technology
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• v.12 no.2
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• pp.67-77
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• 2006

A simple dual sludge process, called as $KNR^{(R)}$ (Kwon's Nutrient Removal) system, was developed for small sewage treatment. It is a hybrid system that consists of an UMBR (Upflow multi-layer bioreactor) as anaerobic and anoxic reactor with suspended denitrifier and a post aerobic biofilm reactor, filled with pellet-like media, with attached nitrifier. To evaluate the stability and performance of this system for small sewage treatment, the pilot-scale $KNR^{(R)}$ plant with a treatment capacity of $50m^3/d$ was practically applied to the actual sewage treatment plant, which was under retrofit construction during pilot plant operation, with a capacity of $50m^3/d$ in a small rural community. The HRTs of a UMBR and a post aerobic biofilm reactor were about 4.7 h and 7.2 h, respectively. The temperature in the reactor varied from $18.1^{\circ}C$ to $28.1^{\circ}C$. The pilot plant showed stable performance even though the pilot plant had been the severe fluctuation of influent flow rate and BOD/N ratio. During a whole period of this study, average concentrations of $COD_{cr}$, $COD_{Mn}$, $BOD_5$, TN, and TP in the final effluent obtained from this system were 11.0 mg/L, 8.8 mg/L, 4.2 mg/L, 3.5 mg/L, 9.8 mg/L, and 0.87/0.17 mg/L (with/without poly aluminium chloride(PAC)), which corresponded to a removal efficiency of 95.3%, 87.6%, 96.3%, 96.5%, 68.2%, and 55.4/90.3%, respectively. Excess sludge production rates were $0.026kg-DS/m^3$-sewage and 0.220 kg-DS/kg-BOD lower 1.9 to 3.8 times than those in activated sludge based system such as $A_2O$ and Bardenpho.