• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.883-888
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• 2013

Coagulation and sedimentation tests were conducted with clay and three different coagulants of soil origin (AC-A, AC-B, AC-C) to determine optimal coagulant types and doses to remove algae in stagnant water bodies such as reservoirs. Raw water had an algal density of 2,950 cells/mL and was dominated by Cyanobacteria. Removal rates of algal density by clay (50 mg/L) were 49% and 85% after 10 and 30 minutes sedimentation, respectively. Other natural coagulants achieved 80-90% removal in 10 minutes and 89-94% removal in 30 minutes of sedimentation after adding 20 mg/L each. AC-A was the optimal coagulant from this study considering algal removal rates and other water quality parameters such as turbidity and pH. For the same removal rates of algae, raw waters with higher algal densities required higher coagulant doses although no strong corelation was observed. The coagulants of soil origin did not impact orgnic contents and pH of raw water, but remove phosphate up to 70%.

• Journal of Life Science
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• v.29 no.3
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• pp.362-368
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• 2019

For the practical application and development of biopolymer flocculant Biopol32 produced by Pseudomonas sp. GP32, its flocculation effect on wastewater from food processing, slaughter houses, and the dyeing industry was investigated. In the food processing wastewater, Biopol32 led to a chemical oxygen demand (COD) reduction rate of 70% and a suspended solid (SS) removal rate of 49% at pH 6.0. In the slaughter house wastewater at pH 4.0, a COD reduction rate of 61% and SS removal rate of 91% were observed, and in the dyeing wastewater, the rates were 72% and 92%, respectively, at pH 5.0. The size of floc formed during the flocculation process was 10 mm at a final concentration of 20 ppm, and the dehydration efficiency was 62%. In both the bioflocculant Biopol32 group and a PAA synthetic flocculant group, optimal flocculant concentration that yielded the best overall dehydration efficiency was 20 ppm, and, at this concentration, the shortest filtration time to reach the natural critical moisture content of 78.1% was attained.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.8
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• pp.837-843
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• 2005

Coagulation influence was evaluated as the pretreatment for ultrafiltration. Coagulation was expected to improve water quality, reduce membrane fouling and increase backwash effect. Continuous operation of UF was employed in order to investigate the influence of coagulation. Alum, PACS and Ferric chloride were used as coagulants separately. From the result of the research, coagulation can improve the treated water quality greatly. Organic removal was increased more than turbidity and showed an improvement of 30.6% at most. All three coagulants presented conspicuous reduction of membrane fouling, among which PACS was the most effective with long term run. Backwash effect differed with different coagulants while Ferric chloride turned out to be the most effective one. The optimum dosage of coagulant resulted in the highest backwash efficiency.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.673-677
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• 2009

현재 상수시설의 경우 갈수록 악화되는 수질과 정수장의 유지관리 인원 상주의 어려움, 기존의 응집, 침전, 여과 정수처리 시스템의 처리성능 증대에 따른 한계성에 직면한 상황이다. 안정적으로 수질의 개선을 통한 장치의 컴팩트화, 유지관리가 편리한 고도정수 수질기준에 만족하는 정수처리 시스템이 필요하다. 본 연구에서는 기존의 정수처리 시설인 혼화지에 응집제와 함께 다양한 비중을 가지고 있는 모래입자를 투입하여 응집제와 모래의 결합에 따른 탁도 제거효율과 슬러지의 양을 비교하였으며, 침전지내에 정류벽을 설치하여 침전지 초반에 가라앉을 수 있도록 유도하여 탁도 및 슬러지양을 비교하였다. 응집제만 투입한 경우보다 시료를 투입한 경우가 탁도제거율과 슬러지양이 상승하는 것을 볼 수 있으며 그중에서도 규사의 경우가 가장 많은 탁도제거율의 상승을 나타냈다. 또한 이중 정류벽을 설치하여 탁도 및 슬러지양을 측정한 결과 이중정류벽을 설치하지 않은 경우보다 탁도제거율 및 슬러지양 또한 높게 측정되었으며 슬러지의 양 또한 침전지 앞부분에 집중되는 것으로 나타났다. 이러한 경우 상기 플럭의 질량이 증가하기 때문에 처리속도를 높이고, 체류시간을 줄이고, 처리를 효율적으로 안정되게 수행하는 것이 가능하다. 본 연구결과를 바탕으로 정수시설의 설치에 있어 시료와 이중정류벽을 함께 사용할 경우 응집제의 절감 또는 침전지의 컴팩트화를 가져올 것으로 예상된다.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.41-42
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• 1995

기존의 정수처리 공정은 응집-침전-급속여과처리를 주로 사용하면서 생물 활성탄처리-오존처리 등을 거치는 공정으로 이루어져 왔다. 그러나 응집제의 투여시 최적 응집제량, 최적 응집제 투여위치, 교반시간, pH 조절 등 번거러운 test가 선행 되어야 하며 처리수에 남아있는 응집제에 의해 2차 오염을 일으켜 침전조의 부지 면적에 따른 대형화등을 초래할 단점이 있다. 따라서 최근에는 이러한 단점을 보완하고 장치의 간소함, 높은 효율의 유지에 따른 후처리 공정의 부하감소 및 운전 조건 인자등의 감소라는 경제적 효과를 기대할 수 있는 막분리공정이 도입되었다. 그러나 분리막 처리공정의 경우 원수에 다량 포함되어 있는 콜로이드 입자들에 의한 flux의 감소 및 fouling 현상으로 인한 막의 수명감소, 처리수량의 감소 및 최적 설계 및 운전 방법등의 새로운 공정에 대한 많은 자료의 확보가 필요하다. 따라서 본 연구는 기존의 정수처리 공정에 있어서 전처리 부분에 해당하는 응집-침전-급속여과처리 공정을 분리막 공정으로 대체 하였을 때 분리막의 재질 및 module의 차이에 따른 처리 능력을 비교하고 각 단위 공정들에 의한 flux 변화, 각 공정별 수질분석, 회복율, 회수율 등을 검토하여 최적 조건의 공정을 확립하여 후처리 공정의 효율을 극대화 하는데 있다.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.689-697
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• 2017

As a fundamental study to apply the new flocculation method using ballast in water treatment process, the optimal conditions for general and ballast coagulant dosage, and pH, which are known to have a significant influence, were derived by response surface methodology. Poly aluminum chloride (PAC) and magnetite ballast were used as a general coagulant and ballast, respectively. Coagulation experiments were performed by jar-tester using the kaolin based synthetic water. The effects of three independent variables (pH, PAC, and ballast) on response variables (turbidity removal rate and average settling velocity of flocs) and the optimum condition of independent variables to induce the optimum flocculation were obtained by 17 experimental conditions designed by Box-Behnken procedure. After performing experiments, the quadratic regression model was derived for each of response variables, and the response surface analysis was conducted to explore the correlation between independent variables and response variables. The $R^2$ values for the turbidity removal rate and the average settling velocity were 0.9909 and 0.8295, respectively. The optimal conditions of independent variables were 7.4 of pH, 38 mg/L of PAC and 1,000 mg/L of ballast. Under these conditions, the turbidity removal rate was more than 97% and the average settling velocity exceeded 35 m/h.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.795-801
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• 2016

This study is on the denitrification process using the sodium alginate and $CaCl_2$ as a flocculant. Removal techniques of nitrate nitrogen from waste water are reverse osmosis, ion exchange, electro dialysis and biological method etc. We tried to remove nitrate nitrogen with flocculation and sedimentation method in the present study. Calcium alginate is expected to form a chelate bond with nitrate nitrogen in the solution. So the effects of flocculantt component, flocculation reaction time, molar ratio of the flocculant, flocculant injection rate are studied to determine the best removal rate of nitrate nitrogen. In addition, we tried to determine the nitrate nitrogen removal mechanism by analyzing the structure and component ratio of the configuration after the agglutination precipitate by FE-SEM and EDS. As a result, the nitrate nitrogen removal mechanism is turned out to form calcium-nitro-alginate, and the best mole ratio of flocculating agent is 1 : 1, the injection rate of the flocculant was up to 2%, the removal rate of the nitrate nitrogen to be 56.7% in the synthetic wastewater.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.8
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• pp.839-846
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• 2008

The flocculation characteristics of polyacrylamide base flocculants were estimated to reduce the moisture content of the dehydrated cakes. The dewaterability for sewage sludge was found to have a marked effect depending on the flocculant type, agitating speed and time, kind of dissolution water, etc. The optimal agitating speed and time were 700 rpm and 3 sec, respectively, in this experimental condition. and the dewaterability was proportion to the agitating speed upto 700rpm. When recycle water as the dissolution water was used, the solution viscosity of all kind of flocculants was decreased. However, the change of its viscosity are not proportioned to the dewaterabilities for each flocculant. Flocculation system of combinations of the first and sencond flocculation using single flocculant was investigated. Effects of the ratio of first and second dosage for dual flocculation on the dewaterability were also investigated. The optimum conditions of dual flocculation system are 75% and 50% as first dosages for low and high viscous flocculant for total dosage of common flocculation, respectively. Based on the results, an overall mechanism of dual flocculation system is proposed and it is envisaged that optimization of flocculation processes in this way can result in considerable savings in cost.

• Membrane Journal
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• v.23 no.6
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• pp.460-468
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• 2013

This study reviewed optimum dosage rate of coagulant and ability to remove dissolved organic carbon without sedimentation in conventional water purification plant. It was confirmed that floc formated by pre-treatment process was broken by impeller of booster pump. Optimum dosage rate of coagulant was 4 mg/L (as PACl 17%) for floc formation through blend, coagulation and after passing through the pump when turbidity of raw water was less than 10 NTU. And average removal rate of dissolved organic carbon was 43% at that time. Maximum removal rate of dissolved organic carbon was 48%, even though coagulation rate was increased gradually until 8 mg/L (as PACl 17%). So removal rate of dissolved organic carbon is not much improved even if dosage rage of coagulant increase. TMP of PVDF (polyvinylidene flouride) pressurized MF process without pre-treatment operated at 0.54 bar and TMP of PVDF pressurized MF process with pre-treatment operated at 0.41 bar.

• Journal of the Korean Society for Marine Environment & Energy
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• v.3 no.1
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• pp.62-69
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• 2000

The study was performed to apply the algae removal system to coagulation-filtration process for minimize the damage to screen interruption of water treatment plants and died of fish by algae bloom on freshwater. Sample used Nokdong river water and Alkalinity, turbidity, chlorophyll-a and pH measured using Jar test and drum filter for coagulation-filtration process to determine optimum coagulation condition. A jar test apparatus and laboratory reactor were used in this study. The highest removal efficiency was observed when condition of flocculation time, coagulant dosage, drum filter rpm and chlorophyll-a concentration were to be 5min, 5mg/ℓ, 3rpm and 90㎍/ℓ, respectively. The average removal efficiencies measured of chlorophyll-a and turbidity using Alum were 50～60% and 30～50%, respectively. PAC was more effective than Alum in removal chlorophyll-a about 20%.