• Journal of the Korea Organic Resources Recycling Association
• /
• v.18 no.1
• /
• pp.89-97
• /
• 2010

In this study, to investigate the effect of chemical pretreatment for livestock wastewater, laboratory scale test for ozonation and linked treatment of sewage were conducted. and the results were obtained as follows. The ozonation of livestock wastewater showed the COD removal rate per hour to be 17%, 78% and 62% at each pH 4, 7 and 10, respectively. With transformation of NBDCOD to biodegradable BDCOD by ozonation, the ratio of SCODcr/TCODcr was increased from 26% to 38%. Accordingly, pretreatment of livestock wastewater affected to the biological post treatment process to elevate removal efficiency by transformation of nonbiodegradable mass to biodegradable mass. As the results of linked treatment of pre-ozonated livestock wastewater and sewage in the MLE process, the treatment efficiencies of TCODcr 93.8%, T-N 74.3%, T-P 89.7%, SS 97.5% were earned at 100% of internal recycle rate. When the internal recycle rate was increased to 150%, the treatment efficiencies of TCODcr 94.5%, T-N 54.5%, T-P 70.8%, SS 98.5% were earned. Also the removal efficiencies of TCODcr 92.6%, T-N 83.1%, T-P 81.9%, SS 98.5% were earned as the internal recycle rate was increased to 200%. Especially, nitrogen removal efficiency in the linked treatment showed 74.3%, 54.5%, 83.1% at 100%, 150% and 200% of internal recycle ratio, respectively, which revealed the tendency of higher removal efficiency than that of sewage treatment.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.1
• /
• pp.97-104
• /
• 2010

At present, the biological nutrient removal (BNR) process for removal of nitrogen and phosphorus is being constructing to keep pace with the reinforced standard of effluent quality and the traditional activated sludge process of preexistence is being promoting to retrofit. At the most case of retrofitting, processes are subjected to be under consideration as alternative BNR process for retrofitting. However, process evaluation methods are restricted to compare only treatment efficiency. Therefore, when BNR process apply, process evaluation was needed various method for treatment efficiency as well as sludge production and aeration cost, and all. In this study, the evaluation method of alternative process was suggested for the case for retrofitting S wastewater treatment plant which has been operated the standard activated sludge process. Three BNR processes for evaluation of proper alternatative process were selected and evaluated with suggested method. The selected $A^2$/O, VIP and DNR processes were evaluated using the mathematical model which is time and cost effective as well as gathered objective evaluation criteria. The evaluation between 5 individual criteria was possible including sludge production and energy efficiency as well as treatment performance. The objective final decision method for selection of optimal process was established through the fuzzy inference.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.42 no.4
• /
• pp.481-491
• /
• 2022

This study investigates the characteristics of the GAC adsorption behavior during the operation of a multi-stage cross-flow filtration and GAC adsorption process for the purpose of devising an advanced treatment of combined sewer overflows (CSOs) and evaluates the regeneration efficiency of spent GAC that has reached the design breakpoint. During the filtration process, suspended substances are easily removed, but dissolved organic substances are not removed, necessitating a process capable of removing dissolved organic substances for the advanced treatment of CSOs. In general, GAC adsorption has been applied under low-concentration organic conditions, such as for water purification and tertiary treatments of sewage, and has rarely been applied under conditions with high organic concentrations, such as with sewage or CSOs. Accordingly, this study will provide a new and interesting experience. Also in this study, the continuous operation and breakthrough characteristics of GAC according to the strength of the inflow organic matter were investigated, electrochemical regeneration was applied to the used GAC, and the regeneration efficiency was evaluated through desorption and re-adsorption tests. The results showed that the breakthrough period was 21 days under high concentration conditions, 28 days at medium concentrations, and 32 days under low concentration conditions. The desorption of adsorbed organic matter through electrolysis occurred in the range of 188 to 609 mgCOD/L depending on the electrolysis conditions, and the effect of the electrolyte type led to the finding that NaOH was slightly higher than H₂O₂.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1996.09a
• /
• pp.65-93
• /
• 1996

우리나라에서는 1962년부터 현재까지 여섯 차례에 걸쳐 경제개발 5개년 계획이 성공리에 추진되어, 지속적인 고도성장을 가져왔다. 그 결과 국민소득과 함께 생활수준은 크게 향상되었다. 그러나 이러한 성장과정에서의 급속한 산업화와 도시화가 수질오염을 크게 증가시키게 되었지만, 여기에 대응하는 하수도 정비 등 환경기술시설의 수질오염 방지를 위한 기반에서 국지적으로 나타났던 수질오염현상이 이제는 넓은 지역으로 확산되어 광역적인 수질오염 현상으로 나타나고 있다. 따라서 정부는 '92년부터 '96년까지 5개년 간의 중기환경종합계획을 세워, 권역별 수질관리계획을 수립하였고, 영양염 배출 규제의 실시, 하구처리시설의 확충 등의 시책을 추진해 나감과 동시에 폐하수의 처리기술 개발등 수질보전 국책 연구과제를 계속 2002년까지 실시하게 되었다.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.4
• /
• pp.61-68
• /
• 2019

As the pollution of water resources deteriorates due to industrialization and urbanization, it is difficult to supply clean water through a water treatment method using chlorine. Therefore, the introduction of advanced water treatment facilities using ozone is on the increase. However, epoxy which is used as waterproofing and anticorrosives and stainless steel used in conventional waterproofing and anti-corrosive methods have deteriorated because of the strong oxidizing power of ozone, causing problems such as leaking. Moreover, it even causes the durability degradation of a concrete. Therefore, in this study, metal spraying system was used as the means of constructing a metal panel with excellent ozone resistance and chemical resistance which is an easier method than an existing construction method. Ozone resistance was evaluated in accordance with the type of metal sprayed coatings to develop a finishing method which can prevent the concrete structure of water treatment facilities from deterioration. Furthermore, electrochemical stability in actual sewage treatment plant environment was evaluated. Experimental results showed that Ti has superior ozone resistance after spraying and the electrochemical stability in the sewage treatment plant environment showed that Ti has the highest polarization resistance of $403.83k{\cdot}{\Omega}{\cdot}cm^2$, which ensures high levels of durability.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.5
• /
• pp.595-601
• /
• 2010

It is evident that Korea will continue its battle with water shortage and alternative program are being taken into action. One of the main actions is reusing 1,800 tons of effluent of 357 sewage treatment plant located nationwide. Therefore this study supplemented ozone oxidation methods that would increase the efficiency of organic oxidation and coagulation. Through this method, fouling will be controled sufficiently by preventing membrane process in the system for advanced sewage treatment. In this study, ozone-coagulation-microfiltration membrane were used. The final removal efficiency of the pretreated water from the result of the ozone-coagulation were 50% of CODcr, 38% of TP and 11% of TOC respectively. Water quality treatment has decreased about 80% for TP. Ozone-coagulation-microfiltration membrane maintains the high flux while decreasing the number of organic matter and the membrane fouling, and reducing the TP. As a result, in order to reuse the water from the sewage, the ozone-coagulation-microfiltration membrane type must be considered in order to achieve the best efficiency.

• Journal of Korean Society on Water Environment
• /
• v.20 no.3
• /
• pp.269-274
• /
• 2004

The performance of a newly designed wastewater treatment process equipped with an anaerobic and two intermittent aeration tanks operated alternately was investigated. During the experimental period, several types of cyclic operating schedules with different aeration and non aeration time were examined for the optimization. At all modes, the removals of organic matter and SS were highly achieved. With respect to T-N removal, however, the cycle length for aeration on/off affected the efficiencies. At the optimal operating mode, the ORP bending point indicating the disappearance of nitrate was observed. Considering the influent wastewater characteristics and cyclic operating schedules, it can be suggested that T-P removal is much more BOD/T-P ratio and/or its load dependant rather than the aeration on/off time. The results obtained from pilot-scale test showed the competitive advantage of this alternating process through an omission of nitrate recycle and operational flexibility against influent load variations when comparing with other continuous flow processes.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.7
• /
• pp.771-777
• /
• 2007

Several endocrine disrupting chemicals(EDCs) were monitored to evaluate the estrogenic activities and the concentrations by yeast two-hybrid assay and enzyme-linked immunosorbent assay(ELISA) in sewage treatment plant(STP) which consist of industrial and domestic line. In the influent of domestic line, estrone, 17$\beta$-estradiol, 17$\alpha$-ethinylestradiol and alkylphenolethoxylate(APE) were detected up to 167.1, 39.7, 7.3 and 145.4 ng/L, respectively. The average removal efficiency of 17$\beta$-estradiol after the activated sludge process was 77.5% and further removed to 80.8% after the sand filtration-ozonation step. These results suggests that the activated sludge process has limited potential to remove the estrogenic activity effectively. The contributions of the estrogenic chemicals to the estrogenic activities were 70.7, 23.3, 3.7 and 2.3% for estrone, 17$\beta$-estradiol 17$\alpha$-ethinylestradiol and APE, respectively, in the domestic line effluents. Therefore, 17$\beta$-estradiol and estrone contributed most of the estrogenic activity in the domestic line effluents.

• Journal of Korean Society of Environmental Engineers
• /
• v.28 no.1
• /
• pp.1-6
• /
• 2006

Biological nutrient removal(BNR) process used in this study, which was packed with EPS(expanded polystylene) media, has more many advantages in aspect of reducing hydraulic retention time(HRT) of the process and having less effect of temperature in the winter season than commercial process in the present. Bench-scale study was performed using domestic wastewater. In the results, it was observed that the T-N removal efficiencies in HRT 6 hr and HRT 4 hr were 55% and 51%, respectively, showing the small reduction (about 4%) of T-N removal efficiency according to shortening of HRT. In comparison of T-N removal characteristic in summer and winter seasons, it showed that T-N removal efficiencies in summer and winter seasons were 65% and 54%, respectively, showing the 11% lower T-N removal efficiency in winter season than in summer season due to deterioration of nitrification in winter season. In the studies of influent loading rate and C/N ratio, the process showed stable effluent quality under the condition of broad influent loading rate and C/N ratio. Therefore, it is anticipated that the developed process in this study could be applicable to small wastewater treatment plant in nutrient removal.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.3
• /
• pp.645-654
• /
• 1994

Photocatalytic oxidation conditions of reactant recirculation flow rate 275 mL/min, aeration rate 2 LPM and $UV+TiO_2+H_2O_2$(500 mg/L) proved to be appropriate for water including organic materials treatment. With increasing turbidity and suspended solids concentration, at turbidity 10 NTU-suspended solids concentration 29 mg/L the phenol degradation efficiency increased, which in turn decreased at turbidity 50 NTU-suspended solids concentration 170 mg/L, however no significant differences were observed, demonstrating similar results with those obtained at zero turbidity and suspended solids concentration. The degradation efficiency of phenol decreased with increasing influent phenol concentrations. The $UV+TiO_2+H_2O_2$ photocatalytic advanced oxidation process conducted is considered to be possibly applied to the drinking water treatment, and the post-treatment process of biological wastewater treatment.