The emergence of micropollutants in natural water sources due to the overuse of anthropogenic chemicals in industry and households has threatened the production of clean and safe tap water in drinking water treatment plants. Conventional physicochemical processes such as coagulation/flocculation followed by sand filtration are not effective for the control of micropollutants, whereas chemical oxidation processes (applying chlorine, permanganate, ozone, etc.) are known to be promising alternatives. Determining the optimum oxidant dose is important issue related to the production of disinfection by-products as well as unnecessary operating cost, and is made possible by simulations of target-micropollutant abatement based on kinetic model equation consisting of second-order rate constant (between the oxidant and the target) and oxidant exposure. However, the difficulty in determining oxidant exposure as a function of complex water quality parameters limits the field application of kinetic model equation. With respect to representative oxidants used in drinking water treatment plants, this article reviews two main approaches for determining oxidant exposure: i) direct measurement in situ and ii) prediction by empirical models based on key water quality parameters. In addition, we discussed research requirements to improve the predictive accuracy of the empirical models for oxidant exposure and to develop a rational algorithm to determine optimal oxidant dose by considering the priority of the target pollutants to be treated.

국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.

Water treatment process simulator is the tool for predicting sequential changes of water quality in a train of unit processes. This predicts the changes through governing equations that represent physicochemical performance of each unit processes with an initial and boundary conditions. Since there is no operational data for the design of a water treatment facility, there is no choice but to predict the performance of the facility by assuming initial and boundary conditions in virtual reality. Therefore, a simulator that can be applied in the design stage of a water treatment facility has no choice but to be built as a numerical analysis model of a deductive technique. In this study, we had conducted basic research on governing equations, inter-process data-flow, and simulator algorithms for the development of simulators. Lastly, this study will contribute to design engineering tool development research in the future by establishing the water treatment theory so that it can be programmed in a virtual world and suggesting a method for digital transformation of the water treatment process.

Microplastics have become a rising issue in due to its detection in oceans, rivers, and tap water. Although a large number of studies have been conducted on the detection and quantification in various water bodies, the number of research conducted on the removal and treatment of microplastics are still comparatively low. In the current research, the inflow and removal of microplastics were investigated for various drinking water treatment plants around the world. Addition to the investigation of filed research, a survey was also conducted on the current research trend on microplastic removal for different treatment processes in the drinking water treatment plants. This includes the researches conducted on coagulation/flocculation, sedimentation, dissolved air flotation, sand filtration and disinfection processes. The survey indicated mechanisms of microplastic removal in each process followed by the removal characteristics under various conditions. Limitations of current researches were also mentioned, regarding the gap between the laboratory experimental conditions and field conditions of drinking water treatment plants. We hope that the current review will aid in the understanding of current research needs in the field of microplastic removal in drinking water treatment.

This study is focused on effects of factors that affect the formation of THMs during chlorination in drinking water treatment. During the chlorination, chlorine consumption is increased by increasing the initial chlorine dose, the pH and the total dissolved solid (TDS) concentration. Also THMs formation is increased up to 58.82 μg/L and 55.54 μg/L by increasing initial chlorine concentration and increasing pH. However, concentration of chloroform is decreased by increasing TDS concentration. This is caused the cation(Na+) of the total dissolved solids preferentially reacts with the functional groups of the organic material which influence the trihalomethane formation. But total trihalomethane formation is increased up to 127.46 μg/L by Br- contained in the total dissolved solids. DOC reduction was not influenced by any of the factors.

A Gravity-driven membrane (GDM) system is one of the promising solutions for household drinking water treatment in the developing countries. In this study, the GDM system was tested for optimizing manual cleaning protocols using three different feed water solutions. Two types of manual cleaning were performed to delay the permeability decrease, cleaning between batches and long-term cleaning. The optimized cleaning between batches protocol was 3 twisting and 10 vertical shaking. And the optimized long-term cleaning protocol was 70 vertical shaking for both the middle region of the module and near the header part. These cleaning protocols allowed the system to produce sufficient water to meet the daily minimum water requirements for a 5-person family, even for using the wastewater influent. The system produced Escherichia coli free water.

A nationwide survey of 8 N-nitrosamines in finished water samples from drinking water treatment plants (DWTPs) in Korea was conducted. The samples were pre-treated by solid-phase extraction (SPE) and analyzed using a gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). According to the study results, four N-nitrosamines (NDMA, NDEA, NMOR, NDBA) were detected for three consecutive years, NMEA and NPYR were only found in samples collected in 2013. Two of these N-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA), have received attention and were the most commonly detected. The concentration of NDMA and NDEA in this study ranged from 0.002 μg/L to 0.013 μg/L and in 0.001 μg/L to 0.008 μg/L, respectively. In comparison to studies performed in EPA(UCMR2), the concentrations of NDMA (from 0.002 μg/L to 0.630 μg/L) and NDEA (from 0.005 μg/L to 0.100 μg/L) observed in the this study were low.

The chemical structures of perfluorinated compounds(PFCs) have unique properties such as thermal and chemical stability that make them useful components in a wide variety of consumer and industrial products. Two of these PFCs, perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA), have received attention and were the most commonly detected. In this study it was analyzed the concentrations of 8 PFCs in samples were collected from drinking water treatment plants for 5 years(2012-2016). PFOS and PFOA were also high concentration and frequency. The mean concentrations of PFOA and PFOS were detected 0.0026-0.0069 μg/L and 0.0009-0.0024 μg/L in samples from drinking water treatment plants. These were relatively lower or similar compared to PFOS concentrations in Osaka(Japan). In general, these levels are below health-based values set by international authoritative bodies for drinking water. These results will be serve as the first monitoring data for PFCs in drinking water and be useful for characterizing the concentration distribution and management of PFCs in future studies.

수처리에 있어 막여과 기술은 안전한 처리수질의 보장, 시스템의 집약화 및 자동화 등의 장점으로 인해 활발히 도입되고 있다. 하지만 핵심 기자재인 막 모듈의 설계나 전체 정수처리 공정의 안정성 부분에 대해서는 아직 기술개발의 여지가 남아 있다. 본 연구에서는 막여과 공정의 연속 운전에 있어서 막오염을 완화시키기 위한 목적으로 수행하는 물리적인 역세척의 효율 향상과 더불어 이 때 발생하는 역세배출수를 막 모듈 외부로 원활히 배출할 수 있도록 한 가압식 막여과 기술과, 이 때 발생한 가압식 막여과 배출수를 이중 구조로 구획된 침지 막조 이용하여 원활히 처리할 수 있는 침지식 막여과 기술을 결합하여 기존 기술에 비해 고회수율의 달성은 물론, 집약적이고 실용적인 2단 막여과 정수처리 시스템을 개발하고자 하였다.

NSF developed NSF p477, which covers POU active media systems. Exact types and quantities of cyanotoxins vary. In 2015 USEPA set recommended health advisories for microcystins in drinking water at or below 0.3 μg/L for children less than 6 years old, and at or below 1.6 μg/L for older children and adults. NSF developed and characterized a natural source for microcystin compounds to be used as a contaminant challenge for the POU active media systems being tested. Analytical methodologies were refined to reliably identify and quantify microcystin at levels in the sub part per billion range. Laboratory column studies using various activated carbons were conducted to determine the relative retention of various microcystin congeners, to assess the appropriateness of various congeners for testing purposes.

The characteristics of filter/adsorber granular activated carbon (F/A GAC) were investigated by measuring various parameters, which include surface area, pore volume, abrasion number, floater, and water-soluble ash. The correlation between parameters was also evaluated. Moreover, rapid small-scale column test (RSSCT) was conducted for adsorption characteristics. Thirteen F/A GAC were tested, and the average values of abrasion number and water-soluble ash were 88.9 and 0.15%, respectively. F/A GAC with the larger external surface area and greater mesopore volume had the lower abrasion number, which indicated that it was worn out relatively easily. Water-soluble ash of coconut-based GAC (about 2.6%) was greater than that of coal-based GAC (less than 1%), and the pH of solution was increased with GAC, which had the higher water-soluble ash. On the other hand, floater of thirteen F/A GAC was divided as two groups, which one group had relatively higher floater (2.7~3.5%) and the other group had lower floater (approximately 0.5%). The results of RSSCT indicated that coconut-based GAC (i.e. relatively higher water-soluble ash) had less adsorption capacity. Moreover, adsorption capacity of coal-based GAC with larger surface area and greater mesopore volume was superior to others.

정수슬러지를 탄화 및 활성처리하여 흡착제를 제조하였으며, 이를 이용한 황화수소 흡착특성을 고찰하였다. 제조 된 흡착제에 대한 BET측정 및 SEM 등 물성분석을 실시하였으며, 황화수소를 대상으로 회분식의 흡착평형실험 을 실시하였다. 실험변수로는 활성처리시 적용되는 약품종류 및 농도 등이 적용되었다. 실험결과, 정수슬러지는 탄화나 약품첨착과정을 통해 커다란 성능 향상이 이뤄짐을 알 수 있었다.

국내 정수장의 70%를 차지하는 15년 이상의 정수장의 대체 방안으로 막 여과 공정의 도입이 검토되고 있다. 동시에 원수의 특성에 적합한 막 여과 공정의 효율적인 공정개발을 위한 노력이 진행되고 있다.(Hur et al., 2006). 본 연구는 침지형 중공사막 모듈에서의 물리적 형태의 막 오염 제어를 위해 역ㆍ공세의 효과를 비교 분석하여 공정의 효율성을 평가하였다. 역ㆍ공세의 시간 및 강도 등의 운전조건을 변경하여 비교한 결과 공세를 통해 중공사막 표면에 존재하는 물리적 오염물질들의 제거가 충분히 되어 역세의 효과 크지 않음이 확인되었다.

The aim of this study was to evaluate the chemical quenching system for residual ozone and to determine the operating condition for the quenching system. Hydrogen peroxide (H₂O₂) and sodium thiosulfate (Na₂S₂O₃) were investigated as quenching reagents for ozone removal, and the tendency of each chemical was notably different. In the case of H₂O₂, the degradation rate of ozone was increased as the concentration of H₂O₂ increase, and temperature and pH value have a significant effect on the degradation rate of ozone. On the other hand, the degradation rate of ozone was not affected by the concentration of Na₂S₂O₃, temperature and pH value, due to the high reactivity between the S₂O₃²- and ozone. This study evaluates the decomposition mechanism of ozone by H₂O₂ and Na₂S₂O₃ with consideration for the water quality and reaction time. Furthermore, the removal test for the quenching reagents, which can be remained after reaction with ozone, was conducted by GAC process.

침지식 분리막 모듈에서 공기강도에 따른 분리막 위치에 대한 오염을 조사하였다. 분리막의 충진밀도가 낮은 곳에서 높은 유체 유속을 나타내었으며, 유체 속도는 기-액 주입률에 비례하였다. 전단응력은 기-액 주입률 및 유체 유속에 비례하였다. 비가역오염(Rir)은 흡입 압력이 가까운 부분에서 가장 높게 나타났다(position 1). 비가역오염에 대한 저항과 분리막 고유 저항의 비(Rir/Rm) 및 비가역오염에 대한 저항과 가역오염의 저항의 비(Rir/Rr)도 position 1에서 가장 높게 조사되었다. 비가역오염(Rir)은 흡입 압력이 높은 곳인 position 1에 오염물질이 축적되어진 결과이다. 분리막 위치에 따른 오염현상은 모듈 디자인 최적화에 중요한 인자임을 알았다.

So many drinking water treatment plants are under various difficulties by new reinforced effluent standards. Since the target turbidity, much higher than annual average, for designing sludge thickener have to be set to confront high turbidity season, the sludge at thickener should be put up for a long time during usual days. So the soluble manganese and chloroform may be formed under the anaerobic environment in the sludge thickener when the sludge retention time is longer with low turbidity. This phenomenon results in difficulties to keep regulatory level of the discharged effluent. For an effort to overcome the problems, a sludge aeration was successfully implemented into the thickening process. As a result, the final effluent quality and sludge volume were much improved; 41 % of manganese, 62 % of chloroform and 35 % of sludge volume. Additionally, effluent quality was improved ; 61 % of Manganese on aeration with pH control and we could make sure of stability effluent quality despite a long sludge retention time. We recommended the standard of installation sludge aeration equipment to nationally supply water treatment plant under effluent water quality problem ; Manganese, Chloroform, etc.

H2S adsorption characteristics of adsorbent made by drinking water treatment sludge were investigated. For analyses of the manufactured adsorbent, various methods such as scanning electron microscope(SEM), measurements of BET surface area were adopted. As the major adsorption characteristic, breakthrough curve was measured by using a continuous fixed bed adsorption column for operating variables such as aspect ratio(L/D, 3∼9), gas flow rate(0.2∼1.0 liter/min) and type of samples. The experimental results showed that the breakthrough pint decreased with increasing gas flow rate, but increased with increasing aspect ratio. It was also found that the physical and chemical treatments of drinking water treatment sludge are very important for the improvement in H2S adsorption capacity due to property changes of the sludge.

현재 막여과 공정은 정수처리에서 많은 관심을 받고 있다. 그러나 막여과 공정은 저압 운전이 가능한 정밀/한외여과 분리막을 이용할 때는 효과적인 용존성 유기물 제거가 이루어지지 않으며 막오염 현상으로 분리막의 투과도 감소가 일어난다. 고압 분리막을 이용할 경우 양질의 수질은 얻을 수 있으나 고압 운전으로 인하여 운전비용의 소모가 높다. 따라서 최근 분리막의 효율적인 정수처리 적용과 성능 향상을 위해서 다른 물리화학적 공정과 결합한 혼성공정에 대한 다양한 접근이 이루어지고 있다. 본 연구에서는 혼성공정으로 응집, 흡착, 특정 화학반응, 막표면 코팅 등과 정밀/한외여과 공정을 결합한 경우의 특징, 처리효율, 고려사항 등을 고찰하였다.

분리막을 이용한 정수처리 공정의 최적화를 위하여 유기물 성분인 humic acid와 탁도를 유발하는 kaolin을 모사 용액으로 제조하여 막내 비저항 값을 최소화하면서 flux의 안정된 경향을 나타내는 최적의 운전 조건을 검토하여 보았다. 그 결과 압력이 증가함에 따라 낮은 비저항값에서 효율적인 분리막을 운전할 수 있으며 선속도가 증가함에 따라 높은 전단율에 의해 cake load는 줄어들었으며 이에따라 비저항값과 flux는 증가하는 경향을 나타내었다. 따라서 최적의 운전조건은 압력 2.0 kgf/cm2, 선속도 0.92 m/sec으로 알 수 있었다.