• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3139-3143
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• 2007

The objective of this paper was to investigate the mixing characteristics of an three-stage inline coagulant mixing system experimentally. Wastewater samples of pH 8.5 and initial turbidity 1,000NTU were taken from a site of tunneling work. At the constant dosage, 0.36mL/L, of polymer as coagulant aids, the coagulation efficiency with the dosage of PAC as coagulant was about 4${\sim}$6% at 10 minutes after sampling. In the case of 2 different velocity gradient conditions, the efficiency of turbidity removal was increased about 6.5${\sim}$8% with increasing the dosage of coagulant while, the efficiency was increased about 20${\sim}$21.5% with increasing the dosage of coagulant aids. The efficiency of turbidity removal with the settling time after sampling was about 90% after 1 minute, and the efficiency was about 95% after 5 minutes.

• 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.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.506-513
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• 2007

One of the most widely used static mixers is Sulzer type mixer. However the structure of the element is so complicated that the mixing efficiency is better than others, whereas the pressure drop is larger than the others. Therefore new elements are necessary to reduce the pressure drop and to minimize the decrease of the mixing efficiency compared with the Sulzer ones. The objectives of this study are to develop new static mixer and to perform the experimental investigation in order to evaluate the performance of the new one, and to investigate the applicability of the one in an inline coagulant mixing system for water treatment, The pressure drops of the new static mixer elements were about 4-12% lower than that of the Sulzer SMX one, and the mixing efficiency of the Sulzer SMX one was about 2-5% higher than that of the new ones. The inline coagulant mixing system with a new static mixer element performed significantly better than the traditional mechanical mixing system for turbidity removal.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.459-469
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• 2009

It is well known that coagulation pretreatment can reduce foulants prior to membrane filtration. The purpose of this research was to investigate the effects of coagulation on fouling of ceramic microfiltration membrane($0.1 {\mu}m$) using pilot plant of $150m^3/day/train$ capacity. Train A membrane system has pretreatment process of ozonation and coagulation while train B has only coagulation. Two types of coagulation operation were investigated: back mixer(rapid mixing with or without slow mixing) which is a conventional mechanically stirred mixer and an inline static mixer. Ozone dose rate for train A was 1 mg/L and ozone contact time was 12 min. The coagulation dose(PACl 10% as $Al_2O_3$) rate was changed 20~40 mg/L according to experimental schedule. In this experimental conditions, the coagulation of back mixer type with rapid mixing(GT=72,000) and slow mixing(GT=45,000) was the best effective in reduction of ceramic membrane fouling regardless preozonation. Especially, the effect of inline static mixer was sensitive to change in water quality. Ozonation mainly affected irreversible fouling rather than reversible fouling in accordance with less adsorption of NOM on the membrane surface. Thus, the increase rate of the nomalized TMP(trans membrane pressure) at $25^{\circ}C$ for train A was relatively lower than that of train B under same coagulation process with same coagulant dosage. The best performance of ceramic membrane appeared in case of combined process with ozonation, therefore this integrated process is able to archive less coagulant dosing and secure a stability of ceramic membrane system.