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회동수원지의 정수처리 공정을 위한 DAF pilot plant 운영 성능평가
맹민수,김동현,신귀암,독고석,Maeng, Minsoo,Shahi, Nirmal Kumar,Kim, Donghyeun,Shin, Gwyam,Dockko, Seok 대한상하수도학회 2020 상하수도학회지 Vol.34 No.6
A 1,000 ㎥/d DAF(dissolved air flotation) pilot plant was installed to evaluate the performance of the floating process using the Nakdong River. Efficiency of various DAF operations under different conditions, such as hydraulic loading rate, coagulant concentration was evaluated in the current research. The operation conditions were evaluated, based on the removal or turbidity, TOC(total organic carbon), THMFP(trihalomethane formation potential), Mn(manganese), and Al(aluminum). Also, particle size analysis of treated water by DAF was performed to examine the characteristics of particles existing in the treated water. The turbidity removal was higher than 90%, and it could be operated at 0.5 NTU or less, which is suitable for the drinking water quality standard. Turbidity, TOC, and THMFP resulted in stable water quality when replacing the coagulant from alum to PAC(poly aluminum chloride). A 100% removal of Chl-a was recorded during the summer period of the DAF operations. Mn removal was not as effective as where the removal did not satisfy the water quality standards for the majority of the operation period. Hydraulic loading of 10 m/h, and coagulant concentrations of 40 mg/L was determined to be the optimal operating conditions for turbidity and TOC removal. When the coagulant concentration increases, the Al concentration of the DAF treated water also increases, so coagulant injection control is required according to the raw water quality. Particle size distribution results indicated that particles larger than 25 ㎛ showed higher removal rates than smaller particles. The total particel count in the treated water was 2,214.7 counts/ml under the operation conditions of 10 m/h of hydraulic loading rate and coagulant concentrations of 60 mg/L.
수돗물에서 미세플라스틱의 물리적 특징이 제거 효율에 미치는 효과
( Nirmal Kumar Shahi ),맹민수 ( Minsoo Maeng ),김동현 ( Donghyun Kim ),독고석 ( Eok Dockko ) 한국물환경학회 2020 한국물환경학회·대한상하수도학회 공동 춘계학술발표회 Vol.2020 No.-
The synthetic polymer with size less than 5 mm is widely defined as microplastics (MPs). It is reported that the MPs with size smaller than 100 μm were found in higher concentration in the treated water. There is not much information available in the literature about the problems resulting from MPs and their removal characteristics from drinking water sources based on size, shape and surface morphology. The main purpose of this study was to investigate the removal behavior (i.e., shape, size and surface morphology) of MPs using a common coagulant, i.e., alum, in the drinking water treatment process, and the enhanced removal by cationic polyamine-coated (PM) sand. The synthetic water sample was prepared by mixing humic acid to represent as natural organic matter and kaolin for required turbidity in tap water. The poly-modified sand particles were achieved by mixing sand with cationic polyamine and kept for 24 h at 23℃. For measurement of MPs, fluorescent technology was chosen. After 30 min sedimentation, supernatant was collected, filtered through 5μm polycarbonate filter (black) and stained with Red Nile solution. The images were acquired and analyzed by ImageJ software. As from the result, the removal of MPs increases with the increasing dose of alum till 30 mg/L (70.7%). However, further increase in the dose leads in sharp decrease in the MPs removal. The analysis was carried out as per the size, shows lower removal of smaller size MPs (10-30 μm) for all different dose of alum. The lower removal was observed for spherical-smooth (SS) MPs, than for nonsymmetric MPs, i.e., elongated-rough (ER), elongated-smooth (FS), spherical-rough (SR) for both 20 mg L<sup>-1</sup> and 30 mg L<sup>-1</sup> alum. The modified orthokinetic flocculation reaction rate constant (k<sub>m</sub>) model was used for shape factor. The k<sub>m</sub> follows the order of FR>FS>SR>SS which is inclined with the result above. In order to enhance the removal of MPs, different dose of polyamine combined with alum and PM-sand were tested. The removal of MPs was found 92.7% and 90.2%, for alum 20 and 30 mg/L combined with PM- sand (500 mg), respectively. This research study reveals, MPs with small-spherical-smooth characteristic are hard to remove by conventional coagulant and process. The PM-sand enhanced the removal of MPs and minimizes the need of high dose of alum and sludge volume. Thus, size, shape and surface morphology of MPs play important roles in the removal of MPs from drinking water.