In this study, solid-liquid separation conditions for coagulation and sedimentation experiments using inorganic coagulant (aluminum sulfate and Poly-Aluminum Chloride (PAC)) were optimized with brine wastewater discharged by the epoxy-resin process. When the turbidity and suspended solid (SS) concentration in raw wastewater were 74 NTU and 4.1 mg/L, respectively, their values decreased the lowest in a coagulant dosage of 135.0 - 270.0 mg Al3+/L. The epoxy resin was re-dispersed in the upper part of wastewater treated above 405.0 mg Al3+/L. The removal efficiencies of turbidity and SS via dosing with aluminum sulfate and PAC were evaluated at initial turbidity and SS of 74 - 630 NTU and 4.1 - 38.5 mg/L, respectively. They increased most in the range from 135.0 - 270.0 mg Al3+/L. The solid-liquid separation condition was quantitatively compared to the correlation of SS removal efficiency between the coagulant dosage and SS concentration based on the concentration of aluminum ions. The empirical formula,   , shows the relationship between SS removal efficiency (R) and coagulant dosage (D) at 38.5 mg/L; it produced high correlation coefficients (r2) of 0.9871 for aluminum sulfate and 0.9751 for PAC.

In the industrial wastewater that occupies a large proportion of river pollution, the wastewater generated in textile, leather, and plating industries is hardly decomposable. Though dyeing wastewater has generally been treated using chemical and biological methods, its characteristics cause treatment efficiencies such as chemical oxygen demand (COD) and suspended solids (SS) to be reduced only in the activated sludge method. Currently, advanced oxidation technology for the treatment of dyeing wastewater is being developed worldwide. Electro-coagulation is highly adapted to industrial wastewater treatment because it has a high removal efficiency and a short processing time regardless of the biodegradable nature of the contaminant. In this study, the effects of the current density and the electrolyte condition on the COD removal efficiency in dyeing wastewater treatment by using electro-coagulation were tested with an aluminum anode and a stainless steel cathode. The results are as follows: ① When the current density was adjusted to 20 A/m2, 40 A/m2, and 60 A/m2 under the condition without electrolyte, the COD removal efficiency at 60 min was 62.3%, 72.3%, and 81.0%, respectively. ② The removal efficiency with NaCl addition was 7.9% higher on average than that with non-addition at all current densities. ③ The removal efficiency with Na2SO4 addition was 4.7% higher on average than that with non-addition at all current densities.

The use of Soluble Cutting Fluids (SCF) is essential in the development of industrial technology. However, it is difficult to decompose biologically due to its high concentrations of organic substances and nitrogen compounds, which interfere with microbial growth. Recently, Advanced Oxidation Processes are being studied both domestically and internationally. Electrolysis is highly adaptable industrial wastewater treatment because it has high removal efficiency and short processing time, regardless of the contaminant’s biodegradable nature. Accordingly, this study shows the characteristics of total nitrogen removal in SCF on the operating time, current density, and electrolytes when using aluminum in a batch-type reactor. The results are as follows: ① Under the condition of without the electrolyte when the current density was adjusted to 40 A/m2, 60 A/m2, or 80 A/m2, the respective T-N removal efficiencies were 71.7%, 80.6%, and 87.2% at 60 min. ② In the comparison for the condition of whether NaCl was added, the removal efficiency of adding NaCl (5 ~ 10 mM) was higher than non-addition at 60 min for all current densities. ③ In the comparison for the condition of whether Na2SO4 (5 ~ 10 mM) was added, the removal efficiency when adding Na2SO4 showed no significant difference compared to non-addition at 60 min for all current densities.

세계적으로 하수처리장 방류수 수질기준이 강화되고 있으며 국내 또한 하수처리장 에너지 자립율을 높이기 위해 하･페수처리장 내 고효율 혐기소화조 및 소화조 전처리 설비가 도입되면서 방류수의 수질은 향상되었다. 그러나, 농축조 및 소화조 후단에서 발생하는 반류수의 농도가 지속적으로 증가하여 하･폐수처리장 내 생물반응조 운영에 악영향을 미치고 있는 실정이다. 반류수는 발생특성상 연속적으로 발생되지 않고 간헐적･주기적으로 발생되며 슬러지 처리계통에서 배출되고 있다. 반류수 발생 시 시간 최대유량 및 농도가 수처리공정 하수유입 부하 대비 100% 이상의 부하증가를 초래하는 경우도 있어 이로 인한 생물반응조의 운영에 어려움을 겪고 있는 실정이다. 이러한 반류수 유량은 유입유량의 1~3%로 적은 양으로 발생되지만 고농도로써 수처리 공정에 충격부하를 유발하기 때문에 전체 처리효율에 악영향을 주는 것으로 알려져 있다. 또한, 질소의 농도가 높기 때문에 반류수에 의한 유입수의 질소부하 증가량은 유입 질소 부하량의 15~25% 이상을 차지한다. 이러한 반류수의 처리를 위해 생물반응조 유입 전 전처리를 통해 부하를 감소시키기 위해 응집침전 방법을 선정하였다. 이에 본 연구에서는 대구 S 하수처리장의 반류수를 대상으로 유입유량 대비 반류수의 연간 유량 및 유입 부하를 파악하였고, 고농도로 유입되는 반류수의 처리를 위해 pH, 응집제 종류, 혼화 시간 및 rpm 의 인자들을 조절하여 응집실험을 진행하였으며, CODCr, T-N, T-P, SS, NH4+의 저감효율을 도출하였다.

최근 전 세계적으로 자원 고갈의 문제에 대비한 신재생에너지 개발 및 자원순환에 대한 관심이 커지고 있다. 특히 수자원은 인간과 생태계에 밀접한 관련이 있는 자원중 하나로 수자원 순환에 대한 다양한 정책이 시행되고 있다. 그중 하수 재이용 정책으로 인해 다양한 처리법이 연구되고 있고, 전기응집 공법 또한 연구가 활발히 진행되고 있다. 전기응집은 전극에 일정전압이 가해지면 금속이 용해되어 수산화물을 생성하고 이것이 폐수 중콜로이드성 물질과 응집하여 침전되면서 오염물질을 제거한다. 전기응집은 시스템의 구성이 간단하여 조작이 쉽고, 온도나 pH에 거의 영향을 받지 않아 경제적인 장점이 있다. 하지만 전기응집 공법은 응집으로 인한 플럭을 제거해야 하며, 이는 여과로 빠르게 분리가 가능해 간단하게 처리할 수 있다. 이에 본 연구에서는 전기응집 처리수에서 발생된 플럭을 제올라이트 여과를 이용해 처리하고자 하였다. 제올라이트를 이용하여 전기응집 플럭이 제거 가능한지 알아보기 위해 탁도를 측정하여 확인한 후, 오염물질 제거에 큰 영향을 미치는 여과유량을 설정하기 위해 EBCT 변화에 따른 실험을 진행하였다. 이때 탁도 뿐만 아니라 CODcr농도와 총인농도, pH를 측정하여 최적 EBCT를 판단하고 재이용수의 수질기준에 만족하는지에 대해 알아보고자 하였다.

우리나라는 지형 특성상 효율적인 수자원 확보가 어려운 실정이기 때문에 안정적이고 지속적인 수자원 공급을 위해 수자원 개발의 필요성이 대두되고 있다. 우리나라의 기존 수자원확보는 대형 댐이나 저수지 형태가 대부분이지만 이는 축조로 인해 대규모 생태계 훼손의 우려가 있어 최근 정부는 해수의 담수화 시스템 개발, 일회성 용수 재사용, 하수 재이용 등 새로운 정책을 시도하고 있다. 우리나라의 하수 재이용율은 매년 꾸준히 증가하는 추세이며 막 분리법, 이온교환 처리법 등 다양한 재이용수 개발공법에 대한 연구가 진행되고 있다. 하지만 막 여과는 막의 수명이 비교적 짧고 막 교환비용이 높은 특성을 가지며, 이온교환 공정은 유지관리가 어렵고 용량에 비해 처리 비용이 고가인 단점이 있다. 따라서 본 연구에서는 이러한 처리법 외에 전기화학적 처리방법인 전기응집에 대한 연구를 시도하였다. 전기응집 공법은 유입 원수에 큰 영향을 받지 않아 폐수성상을 가리지 않고 오염물질을 효과적으로 처리할 수 있으며, 다른 공정과 비교했을 때 설치면적 당 처리 용량이 커서 경제적이다. 이에 본 연구에서는 전기응집 공법에서 영향인자로 알려진 전류밀도, 전극 간격, 교반속도와 시간에 따른 제거효율을 Jar-test를 통해 확인하고 최적조건을 도출하였다. 또한 도출해낸 최적조건에서 전기응집을 이용해 하수처리수의 재이용수로 이용 가능성에 대해 판단하고자 하였다. 전류밀도는 0.036A/cm², 전극간격은 0.3cm, 교반속도와 시간은 100rpm, 5분에서 가장 높은 제거효율을 보여 이를 최적조건으로 결정하였다.

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%∼40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

Acid mine drainage (AMD) has emerged as one of the greatest environmental threats facing mining industry owing to its characteristic low pH, high acidity and elevated concentrations of metals and sulphate content. This study evaluates the efficiency of fly ash as a low cost material to remove heavy metals (Cu, Fe, Mn and Pb) from AMD. The effects of varying contact time, dosage and pH on adsorption were investigated using synthetically prepared AMD. The experiments was conducted in series of batches for adsorption using a mechanical shaker with 50mL AMD at various dosages of fly ash (0.1 - 0.8g/L) and coagulation using a standard jar tester of 1000mL AMD with chemical coagulant dosages (0.5 - 10g/L). Tests were also conducted with 50mL AMD without fly to evaluate the treatment efficiency of fly ash to chemicals. All tests were performed in duplicate for consistency and accuracy. The chemical composition of fly ash was characterized by X-ray fluorescence (XRF) and the result shows the fly ash is rich in calcium (CaO 54.9%). Leaching test of the fly ash was conducted using KLST and TCLP method to compare the results and evaluate the behavior of leaching ash in replenishing acidic media at low pH such as acid mine drainage. pH plays a significant role in heavy metal uptake in this study with increased in pH value the removal rate increased. The optimum dosage for Adsorption was found to be 0.4g/L with 60 min optimum contact time and coagulation 6mg/L with reduced metal concentrations much less than regulation standards for Cu, Fe, Mn and Pb. From all tests conducted fly ash proves more efficient with over 96% removal even at low dosages. The effectiveness of the treatment process will depend on the quality of the fly ash and the AMD. Therefore the use of fly ash for treatment of mine wastewater would represent a new market opportunity for this waste product. Recycling of fly ash will conserve the natural raw materials and abridge the disposal cost. It will also create new revenues and business opportunities while protecting the environment. Most significantly, the two waste products acid mine drainage and fly Ash could be neutralized and when reacted together to produce much cleaner water broadly compared to post process water derived from Lime treated AMD and sulfates removal rates were in the range of 90% in both experiments. Fly ash is more economical, sustainable.

Effects of coagulation types on flocculation were investigated by using a photometric dispersion analyzer (PDA) as an on-line monitoring technique in this study. Nakdong River water were used and alum and ferric chloride were used as coagulants. The aim of this study is to compare the coagulation characteristics of alum and ferric chloride by a photometric dispersion analyzer (PDA). Floc growing rates (Rv) in three different water temperatures (4℃, 16℃ and 30℃) and coagulants doses (0.15 mM, 0.20 mM and 0.25 mM as Al, Fe) were measured. The floc growing rate (Rv) by alum was 1.8∼2.8 times higher than that of ferric chloride during rapid mixing period, however, for 0.15 mM∼0.25 mM coagulant doses the floc growing rate (Rv) by ferric chloride was 1.1∼2.3 times higher than that of alum in the slow mixing period at 16℃ water temperature. Reasonable coagulant doses of alum and ferric chloride for turbidity removal were 0.1 mM (as Al) and 0.2 mM (as Fe), respectively, and the removal efficiency of those coagulant doses showed 94% for alum and 97% for ferric chloride. The appropriate coagulant dose of alum and ferric chloride for removing dissolved organic carbon (DOC) showed about 0.3 mM (as Al, Fe) and at this dosage, DOC removal efficiencies were 36% and 44%, and ferric chloride was superior to the alum for removal of the DOC in water.

The objectives of this paper are the characterization of the pretreatment of wastewater by microfiltration (MF) membranes for river maintenance and water recycling. This is done by investigation of the proper coagulation conditions, such as the types and doses of coagulants, mixing conditions (velocity gradients and mixing periods), pH, etc., using jar tests. The effluent water from a pore control fiber (PCF) filter located after the secondary clarifier at Kang-byeon Sewage Treatment Plant (K-STP) was used in these experiments. Two established coagulants, aluminum sulfate (Alum) and poly aluminum chloride (PAC), which are commonly used in sewage treatment plants to treat drinking water, were used in this research. The results indicate that the optimal coagulation velocity gradients (G) and agitation period (T) for both Alum and PAC were 200-250 s-1 and 5 min respectively, but the coagulation efficiencies for both Alum and PAC were lower at low values of G and T. For a 60 min filtration period on the MF, the flux efficiencies (J/J0 (%)) at the K-STP effluent that were coagulated by PAC and Alum were 92.9 % and 79.9 %, respectively, under the same coagulation conditions. It is concluded that an enhanced membrane process is possible by effective filtration of effluent at the K-STP using the coagulation-membrane separation process.

T-N and T-P in the filtrate from Sludge Treatment Process (STP) was returned to water treatment processing, because T-N and T-P are returned, it makes overload in Advanced Treatment Process. Removal efficiency of T-N and T-P are compared both at using polymer as simple method and at using PFS and polymer as complex method when coagulants was injected in Thickener. In simple method, removal efficiency of T-N and T-P were 95.68% and 99.29% for each. In complex method, removal efficiency of T-N and T-P were 98.07% and 99.90% for each. From the result, removal efficiency of complex method was highly better than simple method. According to increasing of removal efficiency, returned T-N and T-P loading to water treatment process was decreased (Reduced amount of T-N is 0.2309 kg/hr and TP is 0.0145 kg/hr). Also, the amount of a polymer used has been decreased to 80% by using PFS.

Coagulation, flocculation, and dissolved air flotation (DAF) experiments were performed with humic acid to evaluate the influence of operational conditions on removal efficiencies. We investigated coagulation, flocculation, and flotation conditions of humic acid removal using a laboratory-scale DAF system. This paper deals with coagulant type (aluminum sulfate and PSO-M) and the most relevant operational conditions (velocity gradients for coagulation and flocculation, retention time and recycle ratio and flotation time). Results showed that optimal conditions for removing humic acid, yielding CHA removal efficiencies of approximately 85 %, are a recycle ratio of 40 %, coagulant dosages of 0.15 – 0.20 gAl/gHA as aluminum sulfate and 0.03 – 0.12 gAl/gHA as PSO-M, coagulation(400s-1 and 60s), flocculation(60s-1 and 900s or more), and flotation(490 kPa or more and at least 10 min).

This study found that flotation efficiencies for removing algae and micro particles in raw water were optimized on mixing intensity and time of the mixing and flocculation conditions with a continuous DAF system. It is more efficient for mixing intensity at 23.1 s-1 and time at 660 s(Gt value : 15246) to float flocculated floc with the raw water in M water treatment plant. Flotation efficiency was more than about 0.9 when operated pressure and A/S ratio were sustained at 5 kgf․cm-2 and up to 0.056 mL․mg-1. The continuous DAF system made by the study could be continuously operated for 20 days and sustained not exceeding 4 NTU with raw water with low turbidity(13.4 ～ 9.8 NTU).

The Raw water from Deer Creek (DC) reservoir and Little Cottonwood Creek (LCC) reservoir in the Utah, USA were collected for jar test experiments. This study examined the removal of arsenic and turbidity by means of coagulation and flocculation processes using of aluminum sulfate and ferric chloride as coagulants for 13 jar tests. The jar tests were performed to determine the optimal pH range, alum concentration, ferric chloride concentration and polymer concentration for arsenic and turbidity removal. The results showed that a comparison was made between alum and ferric chloride as coagulant. Removal efficiency of arsenic and turbidity for alum (16 mg/L) of up to 79.6% and 90.3% at pH 6.5 respectively were observed. Removal efficiency of arsenic and turbidity for ferric chloride (8 mg/L) of up to 59.5% at pH 8 and 90.6% at pH 8 respectively were observed. Optimum arsenic and turbidity removal for alum dosages were achieved with a 25 mg/L and 16 mg/L respectively. Optimum arsenic and turbidity removal for ferric chloride dosages were achieved with a 20 mg/Land 8 mg/L respectively. In terms of minimizing the arsenic and turbidity levels, the optimum pH ranges were 6.5 and 8for alum and ferric chloride respectively. When a dosage of 2 mg/L of potassium permanganate and 8 mg/L of ferric chloride were employed, potassium permanganate can improve arsenic removal, but not turbidity removal.

본 연구는 황토와 황토에서 분리한 점토(clay fraction)를 이용하여 수용액 내 양이온의 종류와 농도에 따른 점토광물의 분산과 응집의 변화를 알아보고자 하였다. 본 연구를 위하여 사용한 황토는 전남 나주시 동강면 장동리 황토로 지표면으로 부터 90~130 cm 깊이에서 채취하였다. 황토와 황토에서 분리한 점토(〈 2 μm) 그리고 이들 시료로부터 결정질 철과 비결정질 철을 제거한 황토와 점토시료를 이용하여 실험을 실시하였다. 이온의 종류와 농도에 따른 점토광물의 저면간격과 물리적 성질의 변화를 알아보기 위하여 4가지 양이온(Na+, K+, Mg2+, Ca2+)과 이들 이온의 농도(0.001 M~1 M)를 변화시켰을 때 광물의 침강속도와 점토광물의 저면간격의 변화를 연구하였다. 장동리 황토의 주 구성광물은 석영이며, 황토로부터 분리한 점토는 카올리나이트, 일라이트, 버미큘라이트로 이루어져 있다. 장동리 황토의 비결정질 철과 결정질 철의 함량은 각각 16.3 mg/kg과 436 mg/kg으로 주로 결정질 철로 이루어져 있다. 이온농도가 다른 4가지 이온을 추가한 수용액에서 구성 입자의 크기가 작은 점토가 황토에 비하여 분산이 더 잘되었다. 황토광물을 코팅하고 있는 결정질 철과 비결정질 철을 제거하기 전과 제거한 후 광물의 분산실험 결과에서 철을 제거한 시료가 분산이 더 잘 일어났으며 이는 코팅된 철 산화물이 광물입자들의 분산을 방해하는 것으로 사료된다. 수용액 중 이온의 종류와 농도가 광물의 분산에 미치는 영향 실험결과에 따르면 첨가한 이온의 농도가 클수록 그리고 양이온 전하량이 클수록 침강속도가 빨랐다. X-선 회절 분석 결과에 따르면 카올리나이트와 일라이트는 양이온의 종류와 농도에 따른 저면 간격의 변화가 없었다. 하지만 버미큘라이트는 일반적으로 +2가 양이온을 첨가한 경우 저면간격이 14.04 a으로 +1가 양이온의 13.9 a보다 크게 나타났다. 이는 +2가 양이온들의 수화반경이 +1가 양이온보다 크기 때문으로 사료된다. 따라서 광물에 코팅된 철과 수용에 내의 이온의 종류와 농도가 광물의 분산 및 버미큘라이트와 같은 팽창성 점토광물의 저면간격에 영향을 줄 수 있음을 시사한다.

The recycled washwater, which has different water quality and is produced about 5 to 20% of the total water volume treated, affects the unit operation of water treatment, especially coagulation process. However, the effects of recycled washwater on unit operation of water treatment have not been fully investigated. In this study, effects of recycled washwater on coagulation process were investigated to find the optimum coagulation condition by analyzing turbidity, UV254, TOC removal efficiencies. In addition, effects of recycled washwater on residual Al after coagulation were studied by analyzing soluble and particulate Al. The size distribution and fractal dimension of coagulated also analyzed. The recycled washwater was lower pH than the raw water. And the recycled washwater had higher UV254, TOC and residual Al concentration than the raw water. Residual Al concentration of recycled washwater was about 50 times higher than that of raw water. Optimum coagulant dosages on the blending recycled washwater and the raw water for turbidity, UV254 and Al removal were lower than that on the raw water. However, TOC removal increased by increasing coagulant dosage. The size and fractal dimension of coagulated particle produced in the blending recycled washwater were larger, which imply faster settling velocity, than those produced in the raw water only.

This study was conducted to investigate the effect of the prechlorination on algal removal by application of a varying amount of different coagulants, such as LAC, PAC, PACS following the process of coagulation and sedimentation of algae in the Nakdong River. The samples used as a source for the raw water of the Nakdong River were collected from the D Water Purification Plant in Taegu city. With the application of the process of prechlorination, the removal rate of the algae was increased from 10∼25% for Synedra spp., 20∼35% for diatoms and 4∼17% for turbidity. Generally, the removal rate of the algae was increased with the increase of the concentration of the coagulants. The PAC and PACS showed 5% higher removal rate for turbidity as compared to the LAS. On the hand, LAS showed 12% higher removal rate for Synedra spp. as compared to the PAC and PACS. The variations in the removal rate of diatoms with the change of coagulant were not significant. In conclusion, the application of LAS, polymeric coagulant and chlorination for at least 20 minutes could be considered as a reliable treatment process for the removal of source water containing a variety of algae.

This experiment was performed on three parts with prepared coagulants. (1) The characterization of coagulation for PACl coagulants. (2) Comparison of the characterization of coagulation with PAS and PACl coagulants. And (3) Comparison of the characterization of coagulation for the addition of calcium with PACl. Coagulation experiments were conducted with several dosages and pH for each coagulants. For the characterization of coagulation with PACl coagulants, coagulation of Nakdong river waters with three PACls (r=2.0, 2.2, 2.35) showed that the effectiveness of the three coagulants can be considered as r=2.2 > 2.0 > 2.35 which are also the order of higher polymeric aluminum contents. For the comparison of the characterization of coagulation for PAS and PACl coagulants, PAS (r=0.75) coagulants was more effective than other coagulant for the removal of organic matters by sweep floc mechanism with Al(OH)3(s). For comparison of the characterization of coagulation for the addition of calcium with PACl, the presence of divalent cation like Ca2+ was supposed to influence the complex formation of organic anions. From the result of test on coagulation at various pH ranges, the PACl was least affected by the coagulation pH, and the addition of calcium to PACl was very effective for the removal of turbidity and organic materials over broader pH range (pH 4-9).

This study aimed to elucidate the relationship between theoretical parameters affecting the coagulation process and the real coagulation phenomenon applied to the dye wastewater. Emphasis was placed on the effective removal of the suspend particulates. Parameters studied in this study are pH, coagulant concentration and surface potential. Optimal dosages of coagulants by the measurement of the zeta potential at lower then 25℃ are 5×10-3 M of FeCl3 and 1.4×10-6 M of Fe2(SO4)3. The results were well agreeded with the separate jar-test results. Emphasis was also placed on the relationship between water quality and the content of SS. It was found that the wastewater quality is greatly dependent on the amount of SS. At the condition with the best removal of SS, COD and DOC were reduced to 65 % and 85 %, respectively The turbidity at the above condition was reduced from 300 NTU to 0∼1 NTU. Efforts were made to clarify the behavior of the suspend solid as affecting the water quality. 12,000∼13,000 particles/l0mL in 1∼50㎛ size range particulates in the raw wastewater were reduced to 300 particle/l0mL in the same range after treatment. This research has proposed the methodology to find out the optimal condition of coagulation for small scale wastewater treatment plant or chemical coagulation process.

The Dongbok lake water before and after alum coagulation and activated carbon adsorption were analyzed in terms of organic contents, molecular weight distributuin (MWD), and UV-absorbance. Dissolved organic compounds in the Dongbok lake were fractionated into three molecular size classes by gel permeation chromatography. The fractionation was reasonably successful in isolating compounds with MW>10,000 (Fraction Ⅰ) and those with 3,000MW (Fraction Ⅲ. The bulk of the dissolved carbon was present in compounds of molecular weight in the range of 3,000∼10,000. Alum coagulation preferentially treated molecules of high molecular weight, which has molecules larger than 10,000. The dissolved organic carbon (DOC) removal after activated carbon adsorption was high in the Fraction Ⅱ, Ⅲ. The A_260/DOC ratio after alum and activated carbon treatment was high in the Fraction Ⅰ, Ⅱ. This results suggest that the organics remaining after each treatment has a trihalomethane formation potential