• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2321-2327
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• 2015

Three coagulants, alum sulfate(alum), poly aluminum chloride(PAC) and poly aluminum silicate chloride (PASC), were used to remove low to high turbidity and TOC in surface and ground blended water. Laboratory experiments and pilot plant experiments were carried out to evaluate the optimal coagulant and its dosage. To determine the optimized coagulant and its dosage, the turbidity, TOC and pH were measured. The experimental results showed the best removal performance using PASC. The optimal dosage of PASC between 3-20 NTU was found to be 15 mg/L in the jar test. In the pilot test, a 15 mg/L PASC dosage was applied and resulted in the efficient removal of turbidity and TOC between 3.6-27 NTU. The removal efficiency of PASC increased with increasing turbidity and TOC.

• 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.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.12
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• pp.1304-1309
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• 2006

In this study, removal efficiencies of treatment processes with C. tracer which is similar to the characteristics of Cryptosporidium were investigated. The highest removal efficiency of C. tracer was 97.16% when the input dose of PACI(Poly aluminium chloride, $Al_2O_3$(10%)) was 10 mg/L. The higher turbidity and SS removal efficiencies were, the more C. tracer cohesion efficiency increased. Also when pH of the raw water was high, removal efficiency of C. tracer increased. As the correlationship($R^2$) between effluent turbidity after coagulation-precipitation and removal efficiency of C. tracer was 0.9506, removal efficiency of Cryptosporidium could be evaluated by effluent turbidity after coagulation-precipitation. Also the range of C. tracer removal efficiency by sand filtration was $94.00{\sim}95.83%$ and the correlationship($R^2$) between effluent turbidity after filtration and removal efficiency of C. tracer was 0.8704. Therefore, when filtration-effluent turbidity is good under the optimized coagulation condition, removal efficiencies of Cryptosporidium by coagulation-precipitation, sand rapid filtration and sand rapid filtration after coagulation-precipitation are estimated as 1.55 log(97.16%), 1.38 log(95.83%) and 2.31 log(99.51%) respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.842-846
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• 2008

원수의 탁질 중에서 입경이 $10^{-1}$mm이상인 것은 보통침전으로 제거가 가능하지만, 입경이��$10^{-3}mm$이하가 되면 일반적으로 콜로이드입자라고 총칭하며 그대로의 상태로서는 거의 침강되지 않을 뿐만 아니라 급속여과기구에서도 포착되지 않는다. 따라서 급속여과 방식에서는 이와 같은 탁질을 효과적으로 제거하기 위한 전처리로서 응집조작으로 인한 콜로이드상의 탁질을 플록화하여 약품침전이나 급속여과에서 포착되도록 탁질의 성상을 변화시키는 조작이 반드시 필요하다. 또한 양호한 플록을 효과적으로 형성시키는 약품혼화와 플록형성 등을 강구해야 한다. 이에 본 연구에서는 현재 국내에서 운영하고 있는 정수처리시스템의 일부인 혼화지내에 혼화지점의 단면적을 축소시켜 약품혼화효과를 극대화하고 혼화기의 소요동력을 감소시켜 혼화효과를 개선하며 혼화지내 혼화기 운용의 비용 절감 효과를 증가시키기 위한 저에너지형 CF혼화장치를 개발하는데 연구 목적이 있다. 연구결과 CF혼화장치의 설치시 약품 투입 위치에 따라 $2{\sim}6%$정도의 탁도제거율의 상승과 슬러지 높이의 차이를 보이는 것으로 나타났으며 이 실험 결과 약품투입장소에서 혼화지의 Compact화로 인해 급속 혼화를 이룰 경우 더 많은 플록화로 인해 탁도 제거율이 높아지는 것을 알 수 있다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.335-340
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• 1997

원전에서 발생하는 방사성 세탁폐액을 환경방사능 Zero Release 개념하에 완전히 처리하는 공정으로서 역삼투막을 이용한 방법이 연구되고 있는데 이에 앞서 역삼투막 공정의 주요 장애요소인 계면활성제 및 현탁물에 의한 탁도 제거를 위한 전처리 공정으로 활성탄과 한외여과막 결합장치를 제작하여 운전하였으며 실험 결과 90% 이상의 높은 세제 제거율과 60% 이상의 탁도 제거율을 얻을 수 있었다.

• Journal of the Korean GEO-environmental Society
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• v.14 no.8
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• pp.23-27
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• 2013

In this study, efficiency of pre-treatment of turbid seawater was measured where micro-air bubbles were used to remove particles in seawater after input of natural coagulant PGA. Artificial seawater was prepared having the intended trubidity using marine sediments and microalgae. 73.7% of turbidity removal was achieved when 0.5g/L of $AlCl_3{\cdot}6H_2O$ was added in the artificial seawater, but 92.4% of turbidity removal was observed when 0.05g/L of PGA was added in the artificial seawater containing microalgae. In addition, much greater turbidity removal was achieved for microalage than sediments. For both cases, input of 0.1g/L PGA and following additional input of micro-air bubbles for 5 seconds resulted in the maximum removal efficiency where reaction time of coagulation was 1 min and flotation by micro-air bubbles was 10 min. From this study, we concluded that micro-air floation after coagulation could be a possible economical pre-treatment method for highly turbid seawater.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1187-1195
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• 2009

The objective of this study is to investigate the coagulation characteristics of the completely mixed chamber for wastewater treatment. The completely mixed chamber system was composed of the reservoirs, the three-stage mixing and coagulation part with propeller impeller, the injection parts of coagulants, a sedimentation tank and a control panel. Wastewater sample of pH 8.5 and initial turbidity 1,000NTU was prepared using sludge taken from a tunneling work site. The efficiency of turbidity removal with increasing the dosage of coagulant aids increased by about 99%. Increasing coagulant above the optimal dosage, however, the efficiency of turbidity removal decreased.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.761-772
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• 1998

This study was performed to determine the optimum coagulant dosing amount for effective treatment of raw water. The removal rate of turbidity and the variations of water qualities according to various dosage of coagulants such as Alum, PAC and PACS were investigated. The optimum coagulant dosing amount to make the lowest turbidity of water were 35mg/ι t of Alum, 30mg/ι of PAC and 10mg/ι of PACS in case of 5 NTU of raw water turbidity, and 30mg/ι of Alum, 25mg/ι of PAC and 10mg/ι of PACS in case of 10 NTU of that, respectively. The removal rates of turbidity at 4 min. and 8 min. of settling time were 10 and 72% of Alum, 44 and 62% of PAC and 25 and 55% of PACS in case of 5 NTU, and 52 and 70% of Alum, 90 and 95% of PAC and 10 and 28% of PACS in case of 10 NTU, respectively. Judging from the settling capability of floc., the reaction time of floe. formation and removal efficiency of turbidity, PAC was evaluated as more effective coagulant than Alum and PACS. Also PAC was regarded as the most effective coagulant when the water supply was changed sharply and the fluctuation of the surface loading occured with wide and sharp in settling basin. pH and alkalinity of the water were decreased with increasing coagulants dosage. But pH and alkalinity were not decreased below 5.8 which is the standard for drinking water quality, and 10mg/ι which is the limit concentration of floc. breakage, respectively. Residual Al of the treated water was decreased with increasing coagulants dosage in case of 5 and 10NTU of raw water turbidity. $KMnO_4$ consumption of the water was decreased with increasing coagulants dosage. The reduction rate of $KMnO_4$ consumption at the optimum coagulants dosage were 39% of Alum. 18% of PAC and 11% of PACS in case of 5 NTU of raw water turbidity, and 42% of Alum, 27% of PAC and 36% of PACS in case of 10 NTU of that, respectively. Any relationship was not found between the removal rate of turbidity and KMnO$_4$ consumption. TOC of the water was a bit decreased with increasing coagulants dosage up to 30mg/ι but not changed above 30mg/ι of coagulants dosage. The degree of TOC reduction was increased in the order of Alum, PAC and PACS treatment. Zeta potential of the colloidal floe. at the optimum coagulants dosage was in the range of -20~-15mV in case of 5 NTU of raw water turbidity and 0~0.5mV in case of 10 NTU of that. respectively. Although the kinds and dosages of coagulants were different, zeta potential range were fixed under the conditions of the best coagulation efficiency.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.1
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• pp.8-13
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• 2016

This study investigated the removal of a radioactive cesium ($Cs^+$) in the water at the water treatment processes. Since cesium is mostly present as the $Cs^+$ ion state in water, it is not removed by sand filtration, and coagulation with polyaluminum chloride (PACl), powdered activated carbon (PAC) and mixture of PACl and PAC. However, it is known that the removal rate of cesium increases as the turbidity increases in raw water. As the turbidity was adjusted by 74 NTU and 103 NTU using the surrounding solids near G-water intake and yellow soils, removal rate of cesium was about 56% and 51%, respectively. In case of a GAC filtration with supernatants after jar-mixing/setting was conducted, 80% of cesium is approximately eliminated. The experimental results show that it is efficient to get rid of cesium when the turbidity of the raw water is more than 80 NTU. In case of a GAC filtration, about 60% of cesium is removed and it is considered by the effect of adsorption. Cesium is not eliminated by microfiltration membrane while about 75% of cesium is removed by reverse osmosis.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.3
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• pp.269-275
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• 2014

The objective of this study was to investigate the performance characteristics of an inline mixing and coagulation system for water treatment based on the process intensification concept. Three-stage inline mixing and coagulation system was composed of the reservoirs of source wastewater, the fixed quantity injection pumps of coagulants, the mixing and coagulation tubes, a sedimentation tank and a control panel. In the equal dosage of coagulant and coagulant aids, the turbidity removal with increasing the dosage of coagulant aids was about 3 times higher than that with increasing the dosage of coagulant. In the condition of the equal mixing and coagulation time, the turbidity removal of inline mixing and coagulation system was about 4.6 times higher than that of mechanical type.