• Applied Biological Chemistry
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• v.41 no.6
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• pp.465-470
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• 1998

For the need of bio-degradable flocculant in stage of wastewater treatment, some cultural conditions of bioflocculant production were optimized with Aeromonas hydrophila KH-54. About 260 strains of type culture and bacteria isolated from marsh, pond, activated sludge, etc were examined for their ability to flocculate kaolin particles and swine wastewater. Among them, KH-54 showed the highest flocculating activity and was identified as Aeromonas hydrophila according to the cultural, morphological and physiological properties. The maximum production of the flocculant secreted by Aeromonas hydrophila KH-54 was observed in culture medium containing 2.0% mannitol, 0.05% ammonium chloride, 0.02% potassium phosphate dibasic, 0.01% $MgSO_4{\cdot}7H_2O$ and 0.05% yeast extract at initial pH 7.0 when cultured on rotary shaker controlled at $25^{\circ}C$ and 150 rpm. Under the optimized condition, the flocculating ability reached to 770 units/ml of kaolin flocculating activity and 81% of NTU removal efficiency against swine wastewater after 4 days cultivation. The bioflocculant was also effective on various organic wastewaters other than swine wastewater, showing NTU removal rate ranging from 92% to 34%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.7438-7442
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• 2014

An assessment of flocculation was performed by measuring the distribution of the floc size during sedimentation in water works. The size and number of flocs have a greater effect on an evaluation of the efficiency of flocculation rather than the turbidity. The data was collected in situ using particle image velocimetry and image analysis. The measurements were carried out at a water depth of 1m. The removal efficiency of the total organic compounds, UV absorbance and turbidity depended on the size and floc size distribution in flocculation as the G value. The G value of 50 sec-1, 30 sec-1 and 10 sec-1 showed the highest degree of efficiency in the case of an inlet water turbidity of 5 NTU, and the highest degree of efficiency was observed at a G value of 65 sec-1, 40 sec-1 and 10 sec-1 when the inlet water turbidity was 263 NTU. The number of flocs with a distribution of above $1,200{\mu}m$ was 14. The dynamics between two important growth mechanisms were investigated as the energy input changed. This is a certain method that makes use of the size and number of flocs as an efficiency assessment.

• Food Science and Preservation
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• v.23 no.4
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• pp.522-529
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• 2016

Clean rice is useful to save time and labor force against washing rice in the household. Nevertheless the quality characteristics of the rice were not established well since the quality characteristics of the rice depend on types of the processing system. The aims of the current study were to understand the quality characteristics of clean rice prepared from the dry, semi-dry, and wet types of processing systems, and to suggest the appropriate processing system for production of clean rice. Here, we found that the quality of clean rice was improved with the increasing whiteness of rice by the dry type, although the whiteness of rice should be below 42 to satisfy 16.0 NTU of the turbidity for higher head rice ratio. Also, both the semi-dry and wet type systems showed higher ratio of head rice than the dry type system at below 16.0 NTU of the turbidity. These results imply that the wet type is more suitable for the place where rice is consumed fast, and the semi-dry type is more proper for long term storage of rice.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.6
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• pp.699-705
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• 2007

In this study, the improvement of the operation condition and the water quality in water treatment plant by operating information system(OIS) was evaluated for Ansan water treatment plant. The average flow rate of raw water in the year 2005(after constructing the OIS) appeared 15.6 % lower than that in the year 2004(before constructing the OIS). The mean value(12.37 NTU) of raw water turbidity in the year 2005 remained constant, or nearly so with that(12.06 NTU) in the year 2004. The average dosing rates of coagulant appeared 12.06 mg/L in the year 2005 which was higher than 10.31 mg/L in the year 2004. Furthermore, the average turbidity concentration of fresh water in the year 2005 appcared slightly better than that in the year 2004. From $COD_{Mn}$ and BOD concentration of raw water, the water quality in the year 2005 were better than those in the year 2004. The average concentration of $KMnO_4$ in the year 2004 and the year 2005 was 2.95 mg/L and 1.25 mg/L, respectively, and the average concentration of THMs in the year 2004 and the year 2005 appeared 0.038 mg/L and 0.025 mg/L, respectively. Therefore, the fresh water quality in the year 2005 was better than that in the year 2004. In this study, it is considered that the operation of Ansan water treatment plant may be optimized by OIS, and thus the OIS may be very useful method to improve the water quality.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.918-928
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• 2013

The inequitable flow distribution to flocculation basins is an important problem faced in many water treatment plants. This is caused by the structure of a distribution channel, the height differences of outlet weirs etc. But, a modified approach for the structures has no effectiveness to achieve flow equality. The aim of this study is to reduce the inequality by adopting optimized inlet valve opening (%) of the flocculation basins using DOE (Design of Experiments) and RSA (Response Surface Analysis). The inlet valve openings (%) and inflow distributions (%) of 6 paralleled basins were set as factors (X) and characteristics(Y) respectively. 2 level factorial experiments and RSA were conducted for optimization and regression analysis (Y = f(X) + Const.). Adopting the optimized inlet valve opening (%) at field, standard deviation of flow distribution (%) and effluent turbidity was declined from 3.80% to 0.42% and from 0.29 NTU to 0.03 NTU respectively.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.142-149
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• 2010

Tadpole shrimps are aquatic crustaceans adapted to temporary water pool. Since they have been recorded as the living fossil, there are a number of reports on their past and present distribution as well as their morphology and reproduction in foreign countries. However, there are few studies of biology and ecology of tadpole shrimps despite registration as an endangered species by Ministry of Environment, in Korea. This study was carried out to examine the distribution and habitat characteristics of tadpole shrimps (Triops longicaudatus) collected from May 2006 to July 2008 in Korea. Tadpole shrimps were found from the paddy fields and ephemeral pools at 21 countries in South Korea. They appeared between May and July and survived for 30 days, and temperatrue range was $10.7^{\circ}C$ to $33.5^{\circ}C$. The average turbidity of experimental paddy fields was 176.8 (${\pm}239.3$) NTU, and controlled field was 28.9 (${\pm}26.7$) NTU. The life pattern of tadpole shrimps is adapted to a temporary water pool and unstable environmental conditions, and also there was great effect of agricultural activity on the development and growth of tadpole shrimps.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3336-3344
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• 2014

The purpose of this study is small scale coagulation module is developed and demonstrated through a lab-scale test. Recent as a sewage treatment rate increases, have heightened the interest in the necessity on the nonpoint source and developing a small processing unit has been increased. Coagulation sedimentation module in this study is additional growth of floc through swirling in the outside zone, reduction of microstructure floc number and the internal settling zone through vertical/level flow complex sedimentation method after the coagulation process precipitation method as an effective high separation efficiency can be divided was also assessed. Coagulation sedimentation module can increase the load factor was 4.4 times compared to conventional clarifier base on the same volume and surface area through vertical/level flow. In this study, this process was selected formation and maintenance of swirling and uniform flow distribution in the internal settling zone as an important design factor, to derive its FLUENT was used to characteristics of the flow model. Through the simulation of swirling, influent velocity, dimensions of external basin, hopper depth of bottom cone was determined and through analysis of velocity distribution, flow distribution detailed specifications are derived like as diameter and number of effluent hole. Lab-scale($120{\ell}/hr$) test results, influent of 300~800 NTU to less than 10 NTU without polymer feeding was able to operate in the 20minutes retention time(surface loading rate $37.3m^3/m^2$-day), and through analysis FLUENT the possibility of using design parameters were derived.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.469-469
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• 2023

고랭지밭은 집중호우시 토사가 유실되고 고농도의 흙탕물이 하천으로 유입되면서 하류지역의 수질 악화로 사회적·환경적 문제를 초래하고 있다. 이에, 환경부는 비점오염원관리지역을 지정하고 비점오염저감시설을 보급하고 있으나, 저감 노력에도 불구하고 집중호우시 수질 악화는 지속적으로 나타나고 있다. 따라서 발생원 관리 노력이 더욱 많이 필요한 실정인데, 최근 강원도와 환경부에서는 토사유실에 취약한 고랭지밭의 지형적 조건을 개선하여 토양유실을 저감하는 고랭지밭 경사도 완화 사업을 추진하고 있다. 고랭지밭 경사도 완화는 급경사지 및 경사장의 경작지를 계단식으로 조성하여 비점유출을 최소화시키는 발생원 관리방안이다. 그러나, 고랭지밭 경사도 완화에 따른 정량화된 비점유출 저감효과 분석에 관한 연구는 부족한 실정이다. 따라서 본 연구에서는 홍천군 광원리와 창촌리에 조성된 경사도 완화 경작지를 대상으로 강우유출수 모니터링을 수행하였으며, 비점저감효과 정량화를 위해 인근의 경사지 밭에서도 강우유출수 모니터링을 수행하여 대조구로 분석하였다. 강우유출수 모니터링은 2020년 8월에 총 3회(광원리 2회, 창촌리 1회) 수행되었으며, 분석 결과 광원리의 경사도 완화 경작지 평균 수질농도는 탁도 124.4 NTU, SS 111.5 mg/L, TOC 4.6 mg/L로 나타났으며, 대조구의 평균 수질농도는 탁도 1,741.7 NTU, SS 673.3 mg/L, TOC 30.6 mg/L로 나타났다. 광원리의 경사도 완화 경작지는 대조구 대비 수질항목별 83.4 ~ 92.9%의 비점저감 효과가 있는 것으로 나타났다. 창촌리의 경사도 완화 경작지의 평균 수질농도는 탁도 598.1 NTU, SS 414.5 mg/L, TOC 8.5 mg/L로 나타났으며, 대조구 평균 수질농도는 탁도3,487.3 NTU, SS 3,081.2 mg/L, TOC 40.3 mg/L로 나타났다. 창촌리의 경사도 완화 경작지는 대조구 대비 수질항목별 78.9 ~ 86.5%의 수질저감효과가 있는 것으로 나타났다. 경작지의 경사도 완화로 밭에서 발생하는 비점오염 발생을 SS는 최대 86.5%, TOC는 최대 84.9% 줄일 수 있는 것으로 나타났다. 하지만 본 연구 결과는 단년간 모니터링을 통해 도출된 결과이므로 정량화된 비점오염저감효과 도출을 위해서 다양한 강우조건 등을 고려한 지속적인 모니터링이 필요할 것으로 판단되며, 향후 연구에서는 2022년도에 인제군 북면 월학리 신규 조성된 경사도 완화 경작지를 대상으로 강우유출수 모니터링을 수행할 계획이다.

• Korean Membrane Journal
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• v.9 no.1
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• pp.12-17
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• 2007

We performed periodic water-back-flushing using permeate water to minimize membrane fouling to enhance permeate flux in tubular ceramic microfiltration system for water treatment of high turbid source. The filtration time (FT) = 2 min with periodic 6 sec water-back-flushing showed the highest value of dimensionless permeate flux ($J/J_o$), and the lowest value of resistance of membrane fouling ($R_f$), and we acquired the highest total permeate volume $(V_T)\;=\;6.805L$. Also in the result of BT effect at fixed FT = 10 min and BT (back-flushing time) = 20 sec showed the lowest value of $R_f$ and the highest value of $J/J_o$, and we could obtain the highest $V_T\;=\;6.660\;L$. Consequently, FT = 2 min and BT = 6 sec could be the optimal condition in water treatment of high turbid source above 10 NTU. However, FT = 10 min and BT = 20 sec was superior to reduce operating costs because of lower back-flushing frequency. Then the average quality of water treated by our tubular ceramic MF system was turbidity of 0.07 NTU, $COD_{Mn}$ of 1.86 mg/L and $NH_3-N$ of 0.007 mg/L.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.2
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• pp.73-81
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• 2003

The performance of heat exchanger using oscillating heat pipe (OHP) for low temperature waste heat recovery was evaluated. OHP used in this study was made from low finned copper tubes connected by many turns to become the closed loop of serpentine structure. The OHP heat exchanger was formed into shell and tube type. R-22 and R-141b were used as the working fluids of OHP with a fill ratio of 40 vol.%. Water was used as the working fluid of shell side. As the experimental parameters, the inlet temperature difference between heating and cooling water and the mass velocity of water were changed. The mass velocity of water was changed from 30 kg/$m^2$s to 92 kg/$m^2$s. The experimental results showed that the heat recovery rate linearly increased as the mass velocity and the inlet temperature difference of water increased. Finally, the performance of OHP heat exchanger was evaluated by $\varepsilon$-NTU method. It was found that the effectiveness would be 80% if NTU were about 1.5.