• 한국환경과학회지
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• 제8권1호
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• pp.107-113
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• 1999

A new biological nutrient removal system combining $A^2/O$ process with fixed film was developed in this work and the characteristics of denitrification were especially investigated in the combined fixed film reactor(CFFR). Media was added in the anaerobic, anoxic and aerobic reactors, respectively. Tests were made to establish the effluent level of $NO_x-N$, COD, DO and nitrite effects on $NO_x-N$ removal in the CFFR by decreasing hydraulic retention time (HRT) from 10.0 to 3.5 hours and by increasing internal recycle ratio form 0% to 200%. The influent was synthesized to levels similar to the average influent of municipal wastewater treatment plants in Korea. SARAN media with a porosity of 96.3% was packed 40% / 130% / 25% based on its reactor volume, respectively. It was found that COD rarely limited dentrification in the anoxic reactor because of high $C/NO_x/-N$ ratio in the anoxic reactor, while DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent inhibited denitrification in the anoxic reactor. It was proved that the critical points of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent were 0.15mg/L and 10%, respectively. As the internal recycle ratio increased, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent increased. Especially, at the condition of internal recycle ratio, 200%, DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent exceeded the critical points of 0.15mg/L and 10%, respectively. Then, denitrification efficiency considerably decreased. Consequently, it was represented that the control of DO concentration in the anoxic reactor and $NO_2-N/NO_x/-N$ from the aerobic effluent can assure effective denitrification.

• 한국수산과학회지
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• 제57권4호
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• pp.438-447
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• 2024

Tongyeong is an important shellfish harvesting area, that hosts the largest designated sea area for shellfish exports in South Korea. In particular, the Dosan-Poonghwa Sea Area in Tongyeong is a semi-enclosed bay with poor water circulation and significant pollution due to its proximity to urban areas. This study examined the distribution of fecal pollution indicators (total coliforms, fecal coliforms, male-specific coliphages, and norovirus G1/G2) in the influent and effluent of wastewater treatment plants (WWTP). This study assessed the impact of the effluent discharge on shellfish harvesting areas in the Dosan-Poonghwa Sea Area to better safeguard shellfish farms and guarantee the safety of harvested shellfish. A strong positive correlation was observed between total and fecal coliforms in both influent (r=0.974, P<0.01) and effluent (r=0.779, P<0.05), with no other significant correlations observed. The impacts of the effluent was evaluated according to NSSP guidelines. The volume of seawater required to dilute the effluent discharged per day was calculated. This evaluation indicated that surrounding aquaculture areas were not impacted, and no viruses were detected in oysters collected from the Dosan-Pungwha Sea Area.

• 상하수도학회지
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• 제19권5호
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• pp.537-546
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• 2005

This study was carried out to evaluate EPS and SMP variation of sludge and effluent in nitrification and denitrification process with zeolite addition, a possible reduction of effluent DOC by URC(Ultra Rapid Coagulation) process. As a biological wastewater treatment result, EPS formation of both aeration and anoxic sludges are not affect by SRT variation. However, EPS concentration of sludges is higher in aeration tank than in anoxic tank by 6~8 mg EPS/ g VSS. Linear relationship between SMP to DOC indicates that SMP of bulk solution contributes to most of the biological treatment effluent DOC. DOC and turbidity removal efficiency was more improved with URC process than in a conventional coagulation. For pretreatment of UF filtration DOC removal was advanced by URC process than only UF filtration.

• 상하수도학회지
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• 제18권2호
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• pp.215-221
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• 2004

Effluent of wastewater treatment plant is to be disinfected to protect drinking water sources. DOF (Dissolved Ozone Flotation) was developed to meet this purpose. DOF was developed by combining DAF system with ozone. DAF system has good floating power with numerous microbubbles, and ozone has strong oxidation capability. And DOF system has good floating power and strong oxidation capability simultaneously. When DOF was applied to secondary wastewater effluent, color of 11CU in raw water which was secondary effluent was reduced to 1CU by the DOF system. Removal rate of other water quality parameters treated by DOF were also higher than that by DAF, which were proved the strength of oxidation capability of ozone. When ozone concentration of 3.3mg/l were applied in DOF system, general aerobic bacteria were reduced to 5CFU/ml from TNTC (Too many Numbers To Count). With the same ozone concentration, total coliform were not detected at all. These figures are under the numbers of drinking water regulation. These microbes were the target parameters of DOF. It was proved that DOF was very effective in disinfection of wastewater treatment plant effluent as well as in removal of color, turbidity, and T-P.

• 상하수도학회지
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• 제30권6호
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• pp.683-690
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• 2016

Modified coagulants were investigated for the removal of phosphorus from secondary effluent of wastewater treatment. The modified coagulants were prepared by mixing alkali earth metal ions such as calcium and magnesium. The basicity of a coagulant influenced on the removal of phosphorus, and coagulants with basicity of 5.9% showed a better removal of total phosphorus than that of 38.5%. Also, coagulants with alkali earth metals enhanced the performance of coagulation by 10% and resulted in 67.1% for total phosphorus removal. Moreover, the removal of suspended solids and chemical oxygen demand was improved using coagulants with low basicity and earth metal ions. Results of this study demonstrated that the use of coagulants with low basicity, and calcium and magnesium ions is recommended to improve wastewater effluent quality.

• 상하수도학회지
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• 제26권1호
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• pp.123-129
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• 2012

A septic tank is a purification treatment system where night soil and other waste matter is converted into harmless material by the activities of bacteria. Effluent from the septic tank flows into the sewer pipe, and then this effluent affects the quality of water environment and makes foul smell. In this study, through the proper maintenance of septic tank it was tried to minimize the impact of sewer pipe on water quality and fouling smell. BOD removal rate from the septic tank's effluent which exceeded legal cleaning period was investigated for the proper maintenance. BOD Removal rate of the twelve septic tank's effluent is -62.5% to 43.9%. According to the result of BOD removal rate, septic tank cleaning should be done at least once a year. And the pathogenic coliform bacillus in the twelve septic tank's effluent is average 768,000 (MPN/$100m{\ell}$). The chlorine disinfection is needed to remove the pathogenic coliform bacillus in septic tank effluent.

• Journal of Electrochemical Science and Technology
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• 제15권1호
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• pp.190-197
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• 2024

A commercial PbO₂ mesh cylinder electrode was utilized as the anode for the electrochemical degradation of the textile effluent after the biological treatment with the titanium cylinder as the cathode in a self-made tube electrolyzer. The electrochemical performances of the PbO₂ electrode in tube electrolyzer under different initial pH, electrolyte flow rates, current densities and times of the electrochemical degradation were investigated. The experimental results illustrated that the PbO₂ electrode can reduce the chemical oxygen demand (COD) of the textile effluent from 94.0 mg L^-1 to 65.0 mg L^-1 with the current efficiency of 88.3%, the energy consumption of 27.7 kWh kg^-1 (per kilogram of degraded COD) and the carbon emissions of 18.0 kg CO₂ kg^-1 (per kilogram of degraded COD) under the optimal operating conditions. In addition, the COD of the textile effluent could be reduced from 94.0 mg L^-1 to 22.0 mg L^-1 after the fifth electrochemical degradation. Therefore, PbO₂ mesh cylinder electrode in the tube cylinder was promising for the electrochemical degradation of the textile effluent.

• 한국환경과학회지
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• 제8권1호
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• pp.115-123
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• 1999

수영하수처리장 방류수의 해중방류법과 3차 처리 시설 설치의 비용분석을 한 결과는 다음과 같다. 1) 해안에서 4km 거리와 관경을 2m의 해중방류법을 이용한 수용만의 수질을 개선시키는데 소요되는 해중방류관 건설비용은 383억 원이 소요되는 것으로 산출되었다. 2) 수영하수처리장의 유출수를 해중방류관을 통해서 방류할 경우 방류수심을 32m, Diffuser의 길이를 200m로 할 경우의 초기희석배율은 유속에 따라서 56.4∼399.2으로 계산되었다. 3) 질소를 제거하기 위한 순환법의 경우의 20년 동안의 총 비용은 1,364억 원, 인을 제거하기 위한 응집제 첨가 활성슬러지법은 1,010억 원, 해중방류법은 383억 원으로 해중방류법이 3차 처리시설을 설치하는 비용보다 약 2.6∼3.5배 비용을 적게 소요하는 것으로 산출되었다. 4) 해중방류법을 이용할 경우의 수영만의 수질영향을 예측하기 위해서 물질순환모델을 이용하여 예측한 결과 수영만의 수질이 COD, 용존무기질소(DIN)와 용존무기인(DIP)의 전 항목에서 해역환경 II등급을 만족하는 것으로 예측되었다.

• 한국물환경학회지
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• 제28권4호
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• pp.505-511
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• 2012

While the existing sewage treatment facilities are mainly being operated by biological processes, winter-time efficiency improvement and additional phosphorus treatment equipment using chemicals have been required to follow the effluent criteria of TP (0.2, 0.3 and 0.5 mg/L for the zone of I, II and III respectively) and $BOD_5$ (5.0 mg/L) which is intensified from 2012 in Republic of Korea. We made an investigation into actual condition of biological treatment process and calculated the optimal chemical input amount by jar test of supernatant of secondary sedimentation tank to evaluate the process improvement for the intensified criteria. Ejector BAF system for removing TP, $BOD_5$ of sewage effluent was suggested. The concentration of TP from biological process is 0.3-0.8 mg/L, and the input amount of optimal chemical coagulant was above Al/P ratio of 3(1.9 mg/L as Al) to meet the criteria of TP for secondary treatment effluent. From the results of this experiment, the best Al/P ratio for Ejector BAF system was about Al/P ratio of 1, and LV of BAF process for intensified criteria of $BOD_5$ and TP was below 1.97m/hr.

• 한국물환경학회지
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• 제29권2호
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• pp.276-287
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• 2013

Domestic sewage contains increasingly more pharmaceuticals and personal care products (PPCPs), due to rising use of medicines, health supplement food and daily necessities. And various types of industrial wastewater from pollution sources in treatment areas could flow into the public sewerage treatment plants (PSTPs) in metropolitan areas. The conventional PSTPs are designed to treat suspended solids, biodegradable organics, nitrogen and phosphorous from residential and industrial areas and public facilities. However, toxic, conventional, and non-coventional pollutants from non-domestic sources that discharge into sewer system as well as domestic source with various chemicals could not be treated in the conventional PSTPs and discharged untreated to public basin. In this paper we aim to consider the establishment system of effluent standard of PSTPs in comparison with water quality standard of water environment and wastewater discharge regulation. And also we suggest the necessity of regulations on the pretreatment of industrial wastewater as part of efforts to improve water quality in sewerage systems and to protect public basin.