• 한국수산과학회지
• /
• 제37권2호
• /
• pp.85-90
• /
• 2004

The effect of the hydraulic residence time (HRT) for the removal of aquarium waste, such as protein, total suspended solids (TSS) and turbidity were investigated by using a foam separator Protein, TSS and turbidity removal efficiencies were increased with the increase of hydraulic residence time. The optimum hydraulic residence time was 0.5 min, and the highest protein and TSS removal rates were $14.4\;g/L{\cdot}day\;and\;38.9\;g/L{\cdot}day,$ respectively. The tendency of turbidity removal rate and efficiency was similar to that of protein.

• Environmental Engineering Research
• /
• 제25권3호
• /
• pp.400-408
• /
• 2020

Hydrodynamic study of Activated Sludge Process (ASP) is important to optimize the reactor performance and detect anomalies in the system. Residence time distribution (RTD) study has been performed using LiCl as tracer on a pilot scale aeration tank (AT) and ASP, treating the pulp and paper mill effluent. The hydraulic performance and treatment efficiency of the AT and ASP at different operating parameters like residence time, recycle rate was investigated. Flow anomalies were identified and based on the experimental data empirical models was suggested to interpret the hydrodynamics of the reactors using compartment modelling technique. The analysis of the RTD curves and the compartment models indicated increase in back-mixing ratio as the mean hydraulic retention time (MHRT) of the tank was increased. Bypassing stream was observed at lower MHRT. The fraction of dead zone in the tank increased by approximate 20-25% with increase in recycle rate. The fraction of the stagnant zone was found well below 5% for all performed experiments, which was under experimental error. The substrate removal of 91% for Chemical oxygen demand and 96% for Biochemical oxygen demand were observed for the ASP working at a hydraulic mean residence time 39 h MRT with a 20% recycling of activated sludge.

• 한국환경농학회지
• /
• 제24권1호
• /
• pp.6-11
• /
• 2005

A prototype surface flow constructed wetland was built in the upstream area of reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, a tracer test using rhodamine-WT was performed to investigate the flow characteristics and to quantify the observed hydraulic residence time (HRT) for a high-lying cell in the Banwol wetland of the Sihwa constructed wetland. The tracer test indicated that even if flow was mainly observed in the open water area of the Banwol wetland, water flowed continuously in the vegetative area and there was no dead zone. The calculated HRT (51.3 hrs), calculated by dividing the wetland volume by the wetland inflow, exceeded the observed HRT (38.7 hrs), since the short-circuiting of flux resulting from irregular topography and vegetation was not reflected in the calculated HRT. The exit tracer concentration curves were reproduced well by both the plug flow with dispersion and tanks-in-series models, indicating that the performance of the Banwol wetland can be estimated accurately using these models.

• 한국환경과학회지
• /
• 제8권4호
• /
• pp.479-483
• /
• 1999

Nitrifier consortium immobilized in polyvinyl alcohol was used for the removal of ammonia nitrogen from synthetic aquaculture water in the airlift bioreactor. At the aeration rate fo 0.15 vvm and bead packing volume fraction of 20%, airlift bioreactor was operated effectively for a removal of ammonia nitrogen and for a stability of operation. Ammonia nitrogen removal rate by airlift bioreactor was continuously increased with decreasing hydraulic residence time. At the HRT(hydraulic residence time) of 0.3 hour, ammonia nitrogen removal rate was 84.3 g/$m^3$.d and the highest ammonia nitrogen removal rate was 130.8 g/$m^3$.d when HRT was 0.1 hour.

• 한국환경과학회지
• /
• 제4권3호
• /
• pp.221-228
• /
• 1995

Stability of reactor and effect on biofilm characteristics were investigated by varying the hydraulic residence time in an inverse fluidized bed biofilm reactor(IFBBR). The SCOD removal efficiency was maintained above 90 % in the HRT range of 12hr to 2hr, but the TCOD removal efficiency was dropped down to 50% because of biomass detachment from overgrown bioparticles. The reactor was stably operated up to the conditions of HRT of 2hr and F/M ratio of 4.5kgCOD/$m^3$/day, but above the range there was an abrupt increase of filamentous microorganisms. The optimum biofilm thickness and the biofilm dry density in this experiment were shown as $200\mu\textrm{m}$ and $0.08 g/cm^3$, respectively. The substrate removal rate of this system was found as 1st order because the biofilm was maintained slightly thin by the increased hydraulic loading rate.

• 한국수산과학회지
• /
• 제33권3호
• /
• pp.205-212
• /
• 2000

공기 구동식, 고속 폭기식 및 벤튜리식 포말분리 장치를 동일한 용량으로 제작하여 양어장 순환수 중의 단백질,총 부유 고형물 및 탁도를 제거하는데 있어 각 포말 분리장치의 운전 특성을 알아보고자 하였다. 공기구동식 포말분리기의 유략감소가 거의 없었으나 벤튜리식 포말분리기는 $66.1{\%}$정도의 유량감소가 발생하였으며 고속 폭기식 포말분리기는 $77.2{\%}$의 유량감소가 발생하였다. 공기 구동식, 고속 폭기식 및 벤튜리식 포말분리 장치의 단백질 제거속도는 수력학적 체류시간이 증가함에 따라 지수적으로 감소 하였다. 0.32 분 이상의 수력학적 체류시간에서는 공기 구동식 포말분리장치의 제거속도와 제거율이 가장 높게 나타났으며 그 이하의 수력학적 체류시간에 대해서는 고속 폭기식 포말분리 장치의 제거속도와 제거율이 가장 높은 것으로 나타났다. 수력학적 체류시간의 변화에 따른 총 부유 고형물과 탁도의 제거속도와 제거율의 변화는 단백질 제거속도 및 제거율의 변화와 거의 비슷하였으며 벤튜리식 포말분리기는 짧은 수력학적 체류시간에서는 총 부유고형물의 제거 효율이 다른 두 포말분리기에 비해 떨어지는 것으로 나타났다. 탁도의 제거는 공기 구동식 포말 분리기가 가장 우수한 것으로 나타났다.

• 청정기술
• /
• 제13권1호
• /
• pp.16-21
• /
• 2007

본 실험은 질화세균을 고정화한 충전층 생물반응기에서 저농도 암모니아성 질소(total ammonia nitrogen, TAN)의 제거 시 수력학적 체류시간(hydraulic residence time, HRT), 유입수 암모니아성 질소농도 및 온도에 의한 영향을 평가하였다. 수력학적 체류시간이 감소함에 따라 암모니아성 질소의 제거속도는 증가하였고, 암모니아성 질소의 제거 시 최적 수력학적 체류시간은 0.2시간이었다. 수력학적 체류시간이 0.2시간에서 암모니아성 질소의 제거속도는 $226.1\;g/m^3{\cdot}day$, 제거효율은 88.8%을 나타내었다. 유입수 암모니아성 질소 농도가 증가함에 따라 암모니아성 질소의 제거속도는 증가하였다. 온도 $20{\sim}35^{\circ}C$에서 암모니아성 질소의 제거속도와 제거효율은 일정하게 유지했다.

• 유기물자원화
• /
• 제25권2호
• /
• pp.27-31
• /
• 2017

본 연구에서는 자흡식 마이크로버블 발생장치를 운전함에 있어서 수심 변화에 의한 수압이 산소 용해율에 미치는 영향에 대하여 평가하였다. 연구결과, 흡입 공기량의 경우 수압이 증가할수록 노즐 토출부에 작용하는 힘의 증가로 감소하는 경향을 나타내었다. 산소전달계수는 수심이 증가할수록 수압 증가에 의한 흡입 공기량 감소와 반응조 용적의 증가로 감소하는 경향을 나타내었으나 수심이 증가할수록 자흡식 마이크로버블 발생장치에서 발생되는 마이크로버블의 체류시간이 증가하여 산소 용해율은 증가하는 경향을 나타내었다. 그러나 자흡식 마이크로버블 발생장치 용량에 대비하여 수심이 과도하게 깊을 경우 낮은 흡입 공기량 및 산소전달계수로 인하여 산소 용해율은 감소할 것으로 판단된다. 따라서 자흡식 마이크로버블 발생장치 운전 시 수압이 중요한 고려사항이 됨을 확인할 수 있었다.

• 한국해양환경ㆍ에너지학회지
• /
• 제17권1호
• /
• pp.52-62
• /
• 2014

금강 하구언 건설 이후 20년 동안 나타난 수서환경의 각종 변화에 관한 연구결과를 호수측과 하구측을 비교하는 방식으로 정리하였다. 유사한 점은 양측 모두에서 물의 체류시간 증가, 수질악화, 퇴적물내 유기물농도 증가, 하천유입 퇴적물의 이동경로 차단현상이 나타났다. 전체적으로 호수측이 하구측보다 악영향이 강하게 나타났지만, 호수측에서는 영양염농도의 증가와 남조류 대량발생 등 수질악화현상이 두드러지게 나타난 반면, 하구측에서는 퇴적물의 이동경로차단으로 인하여 군산하구내 퇴적현상이 심화되어 정상적인 하구의 기능을 저해하고 있다.

• 한국환경보건학회지
• /
• 제26권4호
• /
• pp.97-104
• /
• 2000

The purpose of this is made an examination of phosphorus loading model for eutrophication response in the Yongsan lake. For the model, we measured the total amount of nutrients derived from the Yongsan river watershed, inflow rate to the Yongsan lake, water quality, and water budget from January to December in 1999. The total amount of precipitation in the Yongsan river watershed was 4,951.7$\times$10$^{6}$ ㎥/y and inflow amount was 2,569.7$\times$10$^{6}$ ㎥/y, therefore the outflow rate of the Yongsan river watershed was 51.9%. The develop loading of total nitrogen was 86,928.1kg/d and that of total phosphorus was 22,007.6kg/d at the Yongsan river watershed, But, as the inflow loading of total nitrogen was 33,962kg/d and the inflow loading of total phosphorus was 2,218kg/d to the Yongsan lake. so each infolw rate was 39.0% and 10.1%. The hydraulic residence time was 34days, total phosphorus loading [L(P)] on the surface area was 23.398g/㎥/y, the hydraulic load( $Q_{s}$) of inflow water was 74.269m/y, the reserve rate of phosphorus in the lake was 0.359, and the settinh velocity of phosphorus was 0.114m/d at the Yongsan lake. Mathematical model of phosphorus loading to estimate the responses of eutrophication at the Yongsan lake is [ $P_{j}$] = 0.838 [L(P)/Q.(1+√ $T_{w}$)$^{-1}$ ] . ] . .