• 환경위생공학
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• 제17권1호
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• pp.12-19
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• 2002

This study was carried out to investigate the optimal condition for granite particle coagulation process by using various chemical coagulation agents. The coagulation of a suspended granite particle was monitored by using various different coagulants, such as $Al_2(SO_4)_3{\cdot}14H_2O,{\;}FeCl_3{\cdot}6H_2O,{\;}SA-solution(KOH{\;}+{\;}Al(OH)_3{\;}+{\;}K_2CO_3{\;}mixture)$ and jade particle. To accomplish this study, analysis of water quality, removing Turbidity and Packing Density were measured with jar-tester. In the results of this experiment, it was found that the removal rate of the granite particle was increased with the decrease of the pH of the sludge. The turbidity(NTU) at the above coagulants was reduced from 95% to 98%. Removed of Turbidity and Packing Density was more efficiency to the SA-solution than others.

• 환경위생공학
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• 제16권3호
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• pp.96-103
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• 2001

This study was carried out to investigate the major factors for the removal of NOMs (Natural Organic Matters) by alum ferric chloride and blended coagulants that consisted of alum and ferric chloride. Investigated factors were pH, the dosage of coagulant, alkalinity, hardness and bloc strength. The particle size contained in the test water came from the Han River was also measured. DOC(Dissolved Organic Carbon) removal at pH 6 was two to three times higher than at pH 8.5. The blended coagulant showed 9 to 10 percent higher DOC removal efficiency and 2 to 4 percent higher turbidity under the same condition. Alkalinity consumption of alum, ferric chloride and blended coagulant was 81%, 90% and 86% of theoretical value, respectively. The limit concentration of alkalinity to avoid pin floe was 10 mg $CaCO_3/L$ when alum was used. Hardness had no apparent effect on coagulation. The residual turbidity and $UV_{254}$ showed a tendency of increasing with floc strength($sec^{-1}$) increase. The order of floe strength was the following; alum >blended coagulant > ferric chloride. The particle counter test showed 89 percent of the small particle size(SPS, $1~5{\;}{\mu}textrm{m}$) and 11 percent of the medium to large particle size(M.LPS, $5~125{\;}{\mu}textrm{m}$). At PH7.85, the particle removal efficiencies of SPS($1~5{\;}{\mu}textrm{m}$) and M.LPS($5~125{\;}{\mu}textrm{m}$) in the coagulation process were 81% and 95%, respectively.

• 상하수도학회지
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• 제23권1호
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• pp.39-46
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• 2009

A method to improve water treatment efficiency by coagulant overdosing for high pH raw water at a drinking water treatment plant (WTP) which had no pH adjusting facilities was investigated. Poly aluminum chloride (PACl) was used for coagulant, and turbidity removal efficiency was evaluated as a function of PACl dosage increases. pH and turbidity of supernatant of jar-tester were 7.10 and 0.50 NTU respectively, when the turbidity, pH, alkalinity, water temperature, conductivity of raw water were 1.75 NTU, 9.38, 46.5 mg/L, $6.4^{\circ}C$, $400{\mu}s/cm$, respectively. Turbidity of settled water was reduced from 2.18 NTU to 0.28 NTU (87% reduction) when PACl dosage was increased from 16 mg/L to 45 mg/L at a full scale WTP. This can be attributed to the recovery of coagulant efficiency by pH reduction with the increase of coagulant dose, however coagulation efficiency was reduced with the formation of Al(OH)4- by PACl addition at higher pH. Coagulant overdosing was proven to be a rapid and effective method for high pH raw water, which can be applied at drinking WTP.

• Membrane and Water Treatment
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• 제14권1호
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• pp.11-18
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• 2023

This work addresses the development of microfiltration ceramic membrane from alumina using extrusion method. The membranes were sintered at different temperatures ranging between 1000 and 1300℃. The alumina was characterized with thermogravimetric analysis, particle size distribution, X-ray diffraction, Fourier transform infrared spectrometer and scanning electron microscope analysis. Subsequently, the effect of sintering temperature on the membrane properties such as porosity, flexural strength, and pure water permeability was investigated and optimized for the sintering temperature. It is observed that with increasing sintering temperature, the porosity of the membranes decreases and the flexural strength, and pure water permeability of the membranes increase. The uncoated and coated membranes were compared at constant flux mode of filtration. Under the turbidity solution recirculation alone at 100 NTU, trans-membrane pressure (TMP) of uncoated membrane remained constant when the filtration flux was below 121 Lm^-2 h ^-1 , while the coated membrane was 111 Lm_-2 h ^-1 . Although suction pressure increased more rapidly at higher turbidity, coated membrane filtration showed better removal efficiency of the turbidity.

• 한국물환경학회지
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• 제31권5호
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• pp.523-532
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• 2015

Hydrocyclone is widely used in industry, for its simple design, high capacity, low maintenance and low operational cost. The objective of this study is to develop hydrocyclone coagulation and filtration system. The system is made of hydrocyclone ballasted coagulation with polyaluminium chloride silicate (PACS) and upflow filter to treat micro particles in urban storm runoff. Roadside sediment particles (< $200{\mu}m$) was mixed with tap water to make various turbid suspensions to simulate urban storm runoff. The filter cartridge was filled with polyethylene media system and ran 1hr per everyday and total operation time were 8.19hrs and backwashing everyday after end of operation. The operation condition of flowrate was $8.2{\sim}11.9m^3/day$ (mean $10.1m^3/day$) and surface overflow rate (SOR) based on filter surface area was $45.5{\sim}65.9m^3/m^2/day$ (mean $55.7m^3/m^2/day$). The range of PACS dosage concentration was 14.0~31.5 mg/L. As the results of operation, the range of removal efficiency of turbidity, SS were 81.0~95.8% (mean 89.5%) 81.8~99.0% (mean 91.4%), respectively. An increase of filtration basin retention time brought on increased of removal efficiency of turbidity and SS, and increase of SOR brought on decreased of removal efficiency. During the first flush in urban area, storm runoff have an high concentration of SS (200~600 mg/L) and the filtration bed becomes clogged and decreased of removal efficiency. Backwashing begins when the drainage pipe valve at the filtration tank bottom is completely open (backwashing stage 1). Backwashing stage 2 was using air bubbles and water jet washing the media for 5 mins and open the drainage valve. After backwashing stage 1, 2, 61.83~64.04%, 18.53~27.51% of SS loading was discharged from filtration tank, respectively. Discharged SS loading from effluent was 7.12~14.79% and the range of residual SS loading in fliter was 2.26~5.00%. The backwashing effects for turbidity, SS were 89.5%, 91.4%, respectively. The hydrocyclone coagulation and filtration with backwashing system, which came out to solve the problems of the costly exchange filter media, and low efficiency of removing micro particles of filter type nonpoint treatment devices, is considered as an alternative system.

• KSBB Journal
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• 제16권4호
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• pp.332-336
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• 2001

본 연구에서는 정수처리 중에서 BAC(Biological activated carbon) 처리의 생물분해능과 같이 NOM의 생분해성 부분을 제거하고자 로프형 미생물 담체를 침전조에 적용하는 공정을 시도하였다. 다양한 운전조건을 적용하여 DOC와 UV$_{254}$ 그리고, 탁도 제거효과를 평가하였는데, 담체 설치는 일반적인 정수처리 공정을 모사한 pilot plant에 첫 번째로 아무 전 처리도 거치지 않은 팔당원수를 바로 지나도록 하였고(Media 1), 두 번째는 팔당원수를 오존으로만 전처리한 후 지나도록 하였으며(Media 2), 세 번째는 전 오존과 응집-침전과정이 끝난 후 지나도록 하였다(Media 3). 원수의 DOC 농도는 1.3~3.4 mg/L이고, UV$_{254}$는 0.027~0.039 ($cm^{-1}$ /)이며, 탁도는 0.3~4.5 NTU 였다. 평균 DOC 농도는 media 1, 2, 3에서 각각 2.2 mg/L, 1.8 mg/L, 1.3 mg/L를 보였다. 반면에 침전조에서는 1.5 mg/L의 농도를 보여 media 3에서 가장 높은 제거량을 나타내었다. 평균 UV$_{254}$ 값은 media 1, 2, 3에서 각각 0.037 ($cm^{-1}$ /), 0.027 ($cm^{-1}$ /), 0.014 ($cm^{-1}$ /)를 나타내었으며, 침전조에서의 UV$_{254}$ 값은 media 3와 비슷한 0.014 ($cm^{-1}$ /)를 보였다. 평균 탁도는 media 1, 2, 3에서 각각 1.1 NTU, 0.9 NTU, 0.5 NTU를 나타내었다. 위의 결과를 보면 로프형 미생물 담체 침전조는 일반적인 침전 공정에 바로 적용할 수 있는 경제적인 장치로 활용 가능할 것이다.

• 한국산업융합학회 논문집
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• 제5권1호
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• pp.75-80
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• 2002

In this study, the initial number of bacteria before ozone sterilizing shows 290 per $1m{\ell}$ in RUN 1 and RUN 2 equally, but the removal rate shows more than 50% in RUN 1, and 100% in RUN 2 respectively when ozone injection amount is $0.28mg/{\ell}$. It is regarded as a satisfactory result that E-coli concentration without ozone contact is 890, rapid removal effect of E-coli is observed in $0.28mg/{\ell}$ of ozone, and E-coli is removed perfectly in $0.84mg/{\ell}$ of ozone. It is thought that an excellent efficiency is obtained for vibrio alginolyticus because the initial number of bacteria before ozone contact is positive, but it is altered to negative after ozone contact. CODcr shows the tendency which is somewhat reduced as the ozone injection is increased, but the general effect is appeared not so much, and it is thought that the tendency is caused by the reason that sea water contains much salt which is estimated as a component of CODcr, therefore it is regarded that ozone contact has not an important effect on salinity. It is thought that the frequency of changing salt water in the fish preserve of a sliced raw fish restaurant can be reduced to under the standard because NTU of 7 days after sea water injection is 0.70 in the experiment of turbidity, hut more than 50% of turbidity removal efficiency is appeared at $0.28mg/{\ell}$ of ozone injection, and it shows 70% at $0.84mg/{\ell}$ of ozone injection in RUN 1 and RUN 2 commonly.

• 상하수도학회지
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• 제29권6호
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• pp.601-608
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• 2015

Pollutants removal efficiency in pretreatment(GAC filter, multi-media filter, disk filter) and RO facilities was investigated for the Jeju Samyang spring water source where raw water intake has been stopped due to sea water intrusion. In addition, preliminary feasibility analysis was conducted between RO and groundwater intake systems. Turbidity removal in 4 different pretreatment processes was less than 25% due to low concentration of turbidity(i.e., less than 0.21 NTU), while multi-media filter is recommended for the pretreatment facility based on the low organic content in raw water as well as cheaper operation and maintenance cost. The average concentration of $Cl^-$ in raw water was 691.4 mg/L, while that of RO permeate was 9.1 mg/L(i.e., removal efficiency was 98.4%). In addition, TDS removal efficiency was 98.1%, which was quite high. The production cost for RO system($Q=4,000m^3/d$) was $362.1won/m^3$ considering installation, operation and maintenance cost for 30 years. While that of groundwater was $262.6won/m^3$ which was low compared to the RO system. However, it is recommended to introduce RO system for Samyang water source rather than new groundwater development because Samyang water source has been discharged to the sea without any usage, while groundwater can be used for other purpose as a sustainable water source.

• 대한환경공학회지
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• 제30권12호
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• pp.1273-1280
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• 2008

본 연구에서는 섬유가공공정 중 머서화공정으로부터 가성소다액를 회수하기 위한 최적의 운전조건을 확립하고자 하였다. 주요 인자들로는 NF/RO막의 적용을 위해 세라믹 막을 이용하여 파울링 지수를 평가, 고분자 막의 적용을 위해 가성소다액의 회수율을 측정, 막의 재생율 향상, 화학세정 조건, 유기물부하, 탁도 및 색도의 최적 제거조건, 그리고 세라믹 막과 고분자막의 복합공정에서의 투과플럭스를 조사하였다. 결과에 따르면, 1단계 공정의 세라믹 한외여과막과 2단계 공정의 나노여과막은 총부유고형물, 잔류유기물, 색도를 포함한 탁도의 제거 그리고 가성소다 용액의 회수에 적합한 공정구성임을 확인하였다. 한외여과막만을 단독으로 사용했을 경우, 총 부유물질과 탁도를 99.0%이상 제거하였고, 색도와 TOC는 각각 74.7%와 49.2%의 제거효율을 얻을 수 있었다. 반면에 세라믹 UF+NF 복합막 공정에서는 총 부유물질과 탁도를 99.9%이상 제거할 수 있었고, 색도는 87.7%, TOC는 78.2%의 제거효율을 얻을 수 있었다. 특히, 복합막 공정에서는 83.7%의 부피회수율일 때 91.3% 가성소다를 성공적으로 회수 할 수 있었다. 이러한 측면에서 복합공정을 통해 가성소다 폐수로부터 순도 높은 가성소다액을 회수할 수 있었으며, 회수된 가성소다액은 공정 내에 재사용이 가능하여 경제적인 이득을 기대할 수 있다.

• 한국물환경학회지
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• 제29권2호
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• pp.170-175
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• 2013

Achieving very low phosphorus levels in treated wastewater will require the installation of additional treatment. Phosphorus removal experiments by chemical coagulation were carried out for the effluent of wastewater treatment plant in this study. TP (total phosphorus) or phosphate were highly related to the addition of PAC (poly aluminium chloride) which is one of the inorganic coagulants. But, organic polymer did not significantly affect the phosphorus removal efficiency. Polymer affected the flocculation of particle especially particle matter less than 10 micrometer so, the number of micro particles was decreased by polymer dose. Chlorination would not affect on chemical coagulation process and TP and turbidity could be effectively removed by the co-addition of PAC and polymer.