• 한국환경보건학회지
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• 제32권1호
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• pp.53-59
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• 2006

This study was carried out to investigate the physicochemical characteristics with the elapsed time of $1\~10$ minutes after adding green tea leaves in the tap water. The results are summarized as follows: 1. $UV_{254}$ measurement increased sharply in direct opposition to increasing conductivity slowly. It is expected that the water soluble organic matters were better extracted than minerals. 2. Residual chlorine decay coefficients evaluated by assuming first-order reaction was increased in proportion to adding weights of green tea leaves. 3. In DBP formation experiments, residual chlorine decreased when reaction time was elapsed. whereas DBPs such as HAAs and THMs increased with the passing of time. From these results, it was showed that residual chlorine decay was related with the formation of DBPs. Therefore, use of boiled tap water in preparation of green tea is suggested if the residual chlorine in the tap water is high.

• 상하수도학회지
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• 제34권5호
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• pp.311-321
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• 2020

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

• 한국지능시스템학회논문지
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• 제24권2호
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• pp.147-154
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• 2014

본 논문에서는 발암물질 저감을 위하여 정수장 염소투입공정 중 전염소 주입에 따른 침전지의 염소 증발량이 주야간, 계절별 현격한 차이가 발생함에 따라 시간대별/계절별/날씨별 유입목표 잔류염소를 변경하고자 운영자의 경험에 기반한 퍼지 모델링 기법을 도입하였다. 퍼지에 의해 설정된 목표 잔류염소농도를 유지하기 위하여 침전지 유입부에 잔류염소 계측기를 추가 설치하여 피드백 Loop 시간을 최소화하였고 지연시간이 긴 시스템에 적용되는 이중 피드백 제어시스템인 캐스케이드 제어를 병행 실시하였다. 이를 통해 소독공정의 고유특성인 시간지연에 대한 선제적 대응 및 침전지 잔류염소농도 변화폭을 7.3배가량 안정화를 시키고 염소소모량을 저감하여 안정적이고 경제적인 물 공급이 가능하도록 하였다.

• 상하수도학회지
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• 제31권6호
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• pp.587-597
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• 2017

This study aimed to develop a method to optimize residual chlorine concentrations in the process of providing water supply. To this end, this study developed a model capable of optimizing the chlorine input into the clearwell in the purification plant and the optimal installation location of rechlorination facilities, and chlorine input. This study applied genetic algorithms finding the optimal point with appropriate residual chlorine concentrations and deriving a cost-optimal solution. The developed model was applied to SN purification plant supply area. As a result, it was possible to meet the target residual chlorine concentration with the minimum cost. Also, the optimal operation method in target area according to the water temperature and volume of supply was suggested. On the basis of the results, this study derived the most economical operational method of coping with water pollution in the process of providing water supply and satisfying the service level required by consumers in the aspects of cost effectiveness. It is considered possible to appropriately respond to increasing service level required by consumers in the future and to use the study results to establish an operational management plan in a short-term perspective.

• 한국물환경학회지
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• 제27권3호
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• pp.334-341
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• 2011

The free residual chlorine of tap water samples, collected from 266 faucets on the water pipe network in Daegu City, was between 0.1 and 0.79 mg/L. On microorganic tests, general bacteria and the coliform goup were not detected and thus the tap water was turned out to be fit to drink. In particular, samples of which free residual chlorine was 0.1 mg/L and over were cultured in R2A agar media at $25^{\circ}C$ for 7 days, and as a result heterotrophic bacteria were detected in 65.9% of samples; (1). The closer tap water got to the faucet from the stilling basin, the lower residual chlorine concentration became but the more the bacterial count became. And, more bacteria were detected in the R2A agar medium than in the PCA medium. (2). In the case of separated strains, most colonies were reddish or yellowish. 16S rRNA sequence was identified as Methylobacterium sp. and Williamsia sp., and yellow strain was identified as Sphingomonas sp., Sphingobium sp., Novosphingobium sp., Blastomonas sp., Rhodococcus sp. and Microbacterium sp. White strain was identified as Staphylococcus sp. (3). Sterilized tap water in polyethylene bottles was inoculated with separated strain and was left as it was for 2 months. As a result, bio-film was observed in tap water inoculated with Methylobacterium sp. and Sphingomonas sp. It was found that heterotrophic bacteria increased when free residual chlorine was removed from tap water in the water pipe network. Thus, there is a need to determine a base value for heterotrophic bacteria in order to check the cleanliness of tap water in the water pipe network.

• 상하수도학회지
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• 제28권1호
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• pp.61-72
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• 2014

Study on effluent organic matter (EfOM) characteristic and removal efficiency is required, because EfOM is important in regard to the stability of effluents reuse, quality issues of artificial recharge and water conservation of aqueous system. UV technology is widely used in wastewater treatment. Many reports have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on EfOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics. The high intensity of pulsed UV would mineralize EfOM itself as well as change the characteristics of EfOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of EfOM. The objective of this study is to investigate the effect on EfOM, chlorine residual, and chlorinated DBPs formation with low pressure and pulsed UV treatment. The removal of organic matter through low pressure UV treatment is insignificant effect. Pulsed UV treatment effectively removes/transforms EfOM. As a result, the chlorine consumption is changed and chlorine DBPs formation is decreased. However, excessive UV treatment caused problems of increasing chlorine consumption and generating unknown by-products.

• 상하수도학회지
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• 제20권1호
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• pp.86-93
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• 2006

In the drinking water treatment, the aesthetic and color problem are caused by the manganese which is occurring and present in the surface, lake and ground water. The most common treatment processes for removing manganese are known for oxidation followed by filtration. In this study, the manganese sand process was used for removing manganese with river bank filtrate as a source. In the manganese sand process, the residual chlorine and pH are important factors on the continuous manganese oxidation. In addition, space velocity (SV) and alum dosage are play a role of manganese removal. Even though manganese removal increased with increasing chlorine concentration, the control of residual chlorine is actually difficult in this process As the results of tests, the residual chlorine concentration as well as manganese removal were effectively achieved at pH 7.5. The optimum attached manganese concentration on manganese sand was confirmed to 0.3mg/L by the experimental result of a typical sand converting to manganese sand.

• 한국수자원학회논문집
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• 제55권spc1호
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• pp.1197-1210
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• 2022

최근 국내에서는 관로 노후화 및 다양한 수질사고 발생으로 인해 상수도 분야에 대한 관심이 급증함에 따라, 상수도 서비스에 대한 이용자들의 수질민원 또한 증가하고 있다. 수질민원의 경우 실제 수질오염뿐만 아니라 소독을 위한 잔류염소농도에 대한 불편을 포함하고 있으며, 따라서 사용자에게 공급되는 잔류염소농도를 균등하게 유지하기 위해 재염소 처리와 같은 다양한 노력이 시도되고 있다. 본 연구에서는 상수관망 내 잔류염소농도 모의를 위해 적용 대상지역의 수질반응계수를 추정하였으며, 수질기준을 만족시키는 동시에 잔류염소농도 균등화를 고려하기 위한 염소 투입 및 재투입 최적화 방법을 제안하였다. 제안된 방법은 국내 대규모 지방상수도를 대상으로 적용하였으며, 격자탐색법을 통해 다양한 염소 투입/재투입 계획을 비교 분석하고, 공급 잔류염소농도의 적합성 및 균등성을 중심으로 최적화한 결과를 제시하였다.

• 한국수자원학회논문집
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• 제57권3호
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• pp.151-164
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• 2024

상수도 공급을 위한 정수장에서 전염소 또는 중염소 공정이 도입된 수처리 공정의 염소농도 관리에 필요한 공정제어를 위하여 AI 기술을 활용한 수질예측 기법이 연구되고 있다. 본 연구에서는 정수장 수처리 공정에서 실시간으로 관측, 생산되고 있는 수량·수질자료를 이용하여 염소소독 공정제어 자동화를 목적으로 침전지 후단의 잔류염소 농도를 예측하기 위한 AI 기반 예측모형을 개발하였다. AI 기반 예측모형은 과거 수질 관측자료를 학습하여 이후 시점의 수질에 대한 예측이 가능한 기법으로, 복잡한 물리·화학·생물학적 수질모형과 달리 간단하고 효율적이다. 다중회귀 모형과 AI 기반 모형인 랜덤포레스트와 LSTM을 이용하여 정수장의 침전지 후단 잔류염소 농도를 예측하여 비교하였다. 최적의 잔류염소 농도 예측을 위한 AI 모형의 입출력 구조로는 침전지 전단의 잔류염소 농도, 침전지 탁도, pH, 수온, 전기전도도, 원수의 유입량, 알칼리도, NH₃ 등을 독립변수로, 예측하고자 하는 침전지 유출수의 잔류염소 농도를 종속변수로 선정하였다. 독립변수는 침전지 후단의 잔류염소에 영향이 있는 정수장에서 확보가 가능한 관측자료중에서 분석을 통해 선별하였으며, 분석 결과 연구대상 정수장인 정수장에서는 중회귀모형, 신경망모형, 모델트리 및 랜덤포레스트 모형을 비교한 결과 랜덤포레스트에 기반한 모형오차가 가장 낮게 도출되는 결과를 얻을 수 있었다. 본 연구에서 제시하는 침전지 후단의 적정 잔류염소 농도 예측값은 이전 처리단계에서 염소주입량의 실시간 제어가 가능토록 할 수 있어 수처리 효율 향상과 약품비 절감에 도움이 될 것으로 기대된다.

• 상하수도학회지
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• 제32권5호
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• pp.411-419
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• 2018

The residual chlorine concentration is an essential factor to secure reliable water quality in the water distribution systems. The chlorine concentration decays along the pipeline system and the main processes of the reaction can be divided into the bulk decay and the wall decay mechanisms. Using EPANET 2.0, it is possible to predict the chlorine decay through bulk decay and wall decay based on the pipeline geometry and the hydraulic analysis of the water distribution system. In this study, we tried to verify the predictability of EPANET 2.0 using data collected from experimental practices. We performed chlorine concentration measurement according to various Reynolds numbers in a pilot-scale water distribution system. The chlorine concentration was predicted using both bulk decay model and wall decay model. As a result of the comparison between experimental data and simulated data, the performance of the limited $1^{st}$-order model was found to the best in the bulk decay model. The wall decay model simulated the initial decay well, but the overall chlorine decay cannot be properly predicted. Simulation also indicated that as the Reynolds number increased, the impact of the wall.