• Journal of Korean Society on Water Environment
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• v.20 no.3
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• pp.275-280
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• 2004

This study was performed to investigate the disinfection efficiency and the formation characteristics of disinfection by-products(DBPs) by chlorination in the sewage effluent. The effluent was sampled from the sewage treatment plants operated in the activated sludge process and the advanced sewage process. The type of DBPs investigated were Trihalomethanes(THMs), Dichloroacetonitrile(DCAN), Chloral hydrate(CH), Dichloroacetic acid(DCAA), Trichloroacetic acid(TCAA). Major findings are as follows. First, the optimum injection concentration for chlorination in sewage effluent were found to be in the range $0.5{\sim}1.0mg\;cl_2/L$. Also, It was found that the chlorine dosage in the effluent of activated sludge process was higher than in the effluent of advanced sewage process. Second, the maximum formation concentration of THMs were $12.7{\mu}g/L$. The THMs formation reaction was finished in a short time of several seconds and chloroform was mainly formed. Also, it was found that the concentration of ammonium nitrogen is higher, the concentration of THMs is lower. Third, it was found that DCAA and TCAA were mainly formed as DBPs by disinfection.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.157-160
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• 2005

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 and inorganic waste binder ;f1y-ash, waste-stone, tailing, phosphogypsum. Then they were burned in different soak temperatures from 1190$^{circ}C$ to 1290$^{circ}C$ with fixed soak time and heating rate at 5 minutes and 20$^{circ}C$/min respectively in order to produce lightweight aggregate (LWA). Experiment were generated to evaluate the quality of LWA as well as the relationship between burning condition and product's quality.

• Environmental Engineering Research
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• v.21 no.4
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• pp.319-332
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• 2016

Micropollutants are often discharged to surface waters through untreated wastewater from sewage treatment plants and wastewater treatment plants. The presence of micropollutants in surface waters is a serious concern because surface water is usually provided to water treatment plants (WTP) to produce drinking water. Many micropollutants can withstand conventional WTP systems and stay in tap water. In particular, pharmaceuticals and endocrine disruptors are examples of micropollutants that are detected at the drinking water, ppb, or even ppb level. A variety of techniques and processes, especially advanced oxidation processes, have been applied to remove micropollutants from water to control drinking water contamination. This paper reviews recent researches on the occurrence and removal of micropollutants in the aquatic environments and during water treatment processes.

• 수도
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• v.24 no.5 s.86
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• pp.16-28
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• 1997

As sewerage works has become one of the major public works in Korea, the employment of advanced and more appropriate sewerage technology has become essential to improve the efficiency of sewerage works. During last 10 years, the Korean Government has made tremendous amount of investment on sewerage works so that treatment plants in 58 cities have treatment capacity which is equivalent to 52.8% of total daily sewage generation in Korea. This remarkable development, however, has heavily depended on one technology, the conventional activated sludge process as more than 95% of the existing plants employ this process, Recently, the Korean Government and local authorities have plans to introduce more appropriate sewage treatment technologies and research and development in this area has become very active. To encourage employing new and appropriate technologies, however, the proper technology evaluation and verification program for new process is needed. The public sector should play a key role in this program since the sewerage works is one of the major public works. In this paper, the technology evaluation and verification programs related with sewerage facilities in the US and Japan are briefly reviewed. The Innovatived and Alternative Technology programs which was operated by US EPA until recently and Environmental Technology Verification(ETV) program which was commenced in 1995 are introduced. The technology verification programs operated in Japan and also in Korea are also reviewed in this paper to propose a future direction for development of the appropriate evaluation and verification system.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.57-63
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• 2015

Recently, Korea's municipal wastewater treatment plants generated amount of wastewater sludge per day. However, ocean dumping of sewage sludge has been prohibited since 2012 by the London dumping convention and protocol and thus removal or treatment of wastewater sludge from field sites is an important issue on the ground site. The hydrothermal carbonization is one of attractive thermo-chemical method to upgrade sewage sludge to produce solid fuel with benefit method from the use of no chemical catalytic. Hydrothermal carbonization improved that the upgrading fuel properties and increased materials and energy recovery, which is conducted at temperatures ranging from 200 to $350^{\circ}C$ with a reaction time of 30 min. Hydrothermal carbonization increased the heating value though the increase of the carbon and fixed carbon content of solid fuel due to dehydration and decarboxylation reaction. Therefore, after the hydrothermal carbonization, the H/C and O/C ratios decreased because of the chemical conversion. Energy retention efficiency suggest that the optimum temperature of hydrothermal carbonization to produce more energy-rich solid fuel is approximately $200^{\circ}C$.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.73-80
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• 2018

In this study, the solids removal characteristics using T-P sludge generated from PACl coagulation were analyzed by laboratory scale and full scale experiment. As the amounts of T-P sludge injection into the raw sewage influent increased at the rate of 0, 1, 2, 3, 4 %, the suspended solids concentrations after 20 minutes setting test decreased to 210, 137, 91, 64, 43 mg/L, respectively. The filtration time required for dewatering test of the raw sewage influent decreased to 982, 728, 658, 581, 492 sec for 0, 1, 2, 3, 4% of T-P sludge injection, respectively. As the amounts of PACl coagulant into the effluent from final setting tank increased at 0, 10, 20, 30, 40 mg/L, the required filtration times for T-P sludge increased into 12.3, 41.7, 53.7, 67.2, 79.5 sec and the dewaterability of T-P sludge decreased. After T-P sludge returned into the primary settling tank on J-si sewage treatment plants, the effluent concentrations of COD, SS, T-N and T-P from primary settling tank into bioreactor decreased by 35.9, 27.9, 22.2, and 52.6% due to the coagulation effects of the T-P sludge. Finally, it was found that the return of T-P sludge into the primary settling tank could result into the sludge reduction having a lower water content of 3.03% p than in case of the only T-P sludge dehydration.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.363-370
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• 2013

Small scale hydropower is one of most attractive and cost-effective energy technologies for installation within sewage treatment plants. This study was conducted to evaluate the potential of a semi-kaplan micro-hydropower (MHP) system for application to sewage treatment plants with high flow fluctuations and a low head. The semi-kaplan MHP is equipped with an adjustable runner blade, and is without a guide vane, so as to reduce the incidence of mechanical problems. A MHP rating 13.4 kWp with a semi-kaplan turbine has been considered for Kiheung Respia sewage treatment plant, and this installation is estimated to generate 86.8 MWh of electricity annually, which is enough to supply electricity to over 25 households, and equivalent to an annual reduction of 49 ton $CO_2$. The semi-kaplan turbine showed a 90.2% energy conversion efficiency at the design flow rate of 0.35 $m^3/s$ and net head of 4.7 m, and was adaptable to a wide range of flow fluctuations. Through the MHP operation, approximately 2.1% of total electricity demand of Kiheung Respia sewage treatment plant will be achievable. Based on financial analysis, an exploiting MHP is considered economically acceptable with an internal rate of return of 6.1%, net present value of 15,539,000 Korean Won, benefit-cost ratio of 1.08, and payback year of 15.5, respectively, if initial investment cost is 200,000,000 Korean Won.

• Korean Journal of Environmental Agriculture
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• v.25 no.1
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• pp.25-33
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• 2006

Objectives of this experiment were to select of the optimum water plant and to investigate the removal efficiency of the major nutrients in the constructed wetland by natural purification method for municipal sewage treatment in the farming and fishing village. For the experiment we used "constructed wetland" which was consisted of aerobic (vertical filter system) and anaerobic systems (horizontal filter system). Both systems were filled with gravel and filter media, and grew water plants on top of them. And then, we investigated several items such as sewage treatment efficiency, growth status of water plants and the absorbed amount of inorganic element in water plants with periodical periods. In aerobic area, removal efficiencies of BOD, COD, T-N and T-P were over 92%, 74%, 25% and 57%, respectively, and then when the water is passed through anaerobic area, the efficiency was over 96%, 84%, 44% and 71%, respectively, which was increased more treatment efficiency than that of aerobic area. Absorption amount of nitrogen and phosphorous in Miscanthus sacchariflorus BENTH were the highest in the water plants as 17.7 and 2.41 g/plant in the aerobic area, respectively. Absorption amounts of nitrogen and phosphorous in Scirpus tabernaemontani GMEL were the highest in the water plants as 8.7 and 1.13 g/plant in the anaerobic area, respectively. For the selection of optimum water plants in the constructed wetland by natural purification method for municipal sewage treatment, it were observed that there were Miscanthus sacchariflorus BENTH, Phragmites japonica STEUD and Phragmites communis TRINIUS in the aerobic area and were Zizania latifolia TURCZ, Scirpus tabernaemontani GMEL, Typha orientalis PRESL, Iris pseudoacorus L and Cares dispalata BOOTT in the anaerobic area.

• Journal of Korean Society on Water Environment
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• v.36 no.6
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• pp.535-545
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• 2020

This study aims to conserve and monitor energy use in public sewage treatment plants by utilizing data from the SCADA system and by controlling the aeration rate required for maintaining effluent water quality. Power consumption in the sewage treatment process was predicted using the equipment's uptime, efficiency, and inherent power consumption. The predicted energy consumption was calibrated by measured data. Additionally, energy efficiency indicators were proposed based on statistical data for energy use, capacity, and effluent quality. In one case study, a sewage treatment plant operated via the SBR process used ~30% of energy consumed in maintaining the bioreactors and treated water tanks (included decanting pump and cleaning systems). Energy consumption analysis with the K-ECO Tool-kit was conducted for unit processing. The results showed that about 58.7% of total energy consumed was used in the preliminary and biological treatment rotating equipment such as the blower and pump. In addition, the energy consumption rate was higher to the order of 19.2% in the phosphorus removal process, 16.0% during sludge treatment, and 6.1% during disinfection and discharge. In terms of equipment energy usage, feeding and decanting pumps accounted for 40% of total energy consumed following 27% for blowers. By controlling the aeration rate based on the proposed feedback control system, the DO concentration was reduced by 56% compared pre-controls and the aeration amount decreased by 28%. The overall power consumption of the plant was reduced by 6% via aeration control.

• Proceedings of the KAIS Fall Conference
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• 2007.05a
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• pp.287-290
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• 2007

We investigated the effect of ultrasound on the dewaterability of sewage sludge. Because, dewatering and disposal of waste sludge is a major economical factor in the operation of wastewater treatment plants. Capillary Suction Time(CST) and Specific Resistance to Filtration (SRF) were used to evaluate the sludge dewatering behaviors. From the results of the experiment, it was found that ultrasonic treatment can improve the dewaterability. We discovered that CST and SRF were highly related, according to the correlation coefficient($R^{2}$).