상수도 공급과정 중 재염소 투입에 따른 잔류염소농도 수체감소계수 예측모델 개발

정보배,구자용,김기범,서지원 대한상하수도학회 2019 상하수도학회지 Vol.33 No.1

This study developed prediction models of chlorine bulk decay coefficient by each condition of water quality, measuring chlorine bulk decay coefficients of the water and water quality by water purification processes. The second-reaction order of chlorine were selected as the optimal reaction order of research area because the decay of chlorine was best represented. Chlorine bulk decay coefficients of the water in conventional processes, advanced processes before rechlorination was respectively 5.9072 (mg/L)-1d-1 and 3.3974 (mg/L)-1d-1, and 1.2522 (mg/L)-1d-1 and 1.1998 (mg/L)-1d-1 after rechlorination. As a result, the reduction of organic material concentration during the retention time has greatly changed the chlorine bulk decay coefficient. All the coefficients of determination were higher than 0.8 in the developed models of the chlorine bulk decay coefficient, considering the drawn chlorine bulk decay coefficient and several parameters of water quality and statistically significant. Thus, it was judged that models that could express the actual values, properly were developed. In the meantime, the chlorine bulk decay coefficient was in proportion to the initial residual chlorine concentration and the concentration of rechlorination; however, it may greatly vary depending on rechlorination. Thus, it is judged that it is necessary to set a plan for the management of residual chlorine concentration after experimentally assessing this change, utilizing the methodology proposed in this study in the actual fields. The prediction models in this study would simulate the reduction of residual chlorine concentration according to the conditions of the operation of water purification plants and the introduction of rechlorination facilities, more reasonably considering water purification process and the time of chlorination. In addition, utilizing the prediction models, the reduction of residual chlorine concentration in the supply areas can be predicted, and it is judged that this can be utilized in setting plans for the management of residual chlorine concentration.

Effect of chlorine dioxide (ClO₂) on polyamide-based RO membrane for seawater desalination process: exposure to high concentration of ClO₂

Koh, Jeong Ho,Jang, Am Balaban Publishers 2017 Desalination and Water Treatment Vol.80 No.-

<P>The most popular disinfecting agents used for biofouling control in the reverse osmosis (RO) system include oxidizing biocides such as chlorine, chloramines and chlorine dioxide. Among them, chlorine (Cl-2) is a traditional water disinfecting agent of choice, and it has been used effectively in cellulose acetate membrane systems. However, it has been informed that chlorine causes an irreversible deterioration on polyamide RO membranes in a very short time. As an alternative sanitizing agent, chlorine dioxide (ClO2) is gaining interests in many disinfect processes including membrane systems, due to its different chemistry and reactivity to chlorine. In this study, therefore, the applicability assessment of chlorine dioxide in seawater reverse osmosis process was performed. Permeate flux, salt rejection and membrane structural analyses were conducted as membrane performance indicators after exposure to chlorine and chlorine dioxide. The results showed that chlorine dioxide-exposed membrane showed very excellent performance in terms of permeate flux and salt rejection, whereas chlorine-exposed membrane showed unstable permeate flux fluctuation and lower salt rejection with increasing time of exposure to chlorine in the soaking bath. From the attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) results of chlorine-exposed membrane showing severe peak intensity decreases under chlorine existence and energy-dispersive X-ray spectrometer (EDS) results of increased chlorine atom ratio, it is suggested that flux fluctuation is a result of molecular structure deformation; chlorination. However, chlorine dioxide-exposed membrane is shown not to chlorinate but to modify polyamide structure, as shown by the results of ATR-FTIR and scanning electron microscopy/EDS analyses and permeate inclination aspect.</P>

Comparison of disinfectants for drinking water: chlorine gas vs. on-site generated chlorine

Yonkyu Choi,Seung-Heon Byun,Hyun-Jung Jang,Sang-Eun Kim,Young-june Choi 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

The feasibility of on-site generated chlorine (OSG chlorine) as an alternative disinfectant to chlorine gas was evaluated in terms of total organic carbon (TOC) removal, disinfection efficiency, biofilm control, disinfection by-products (DBPs) formation, chlorine decay rate, and volatility. Chlorine gas decreased the pH of the treated water by -0.1 per mg/L of free available chlorine (FAC) while OSG chlorine increased the pH by + 0.06 per mg/L. OSG chlorine with more hypochlorite ion (OCl<SUP>-</SUP>) at higher pH was less effective in the inactivation of suspended bacteria and TOC removal but remained in the distribution system longer and controlled biofilm formation more effectively than chlorine gas. The DBPs formation by OSG chlorine was not significantly different from that by chlorine gas except for the reduction of Haloacetonitriles. Hypochlorous acid (HOCl) was more volatile than OCl<SUP>-</SUP>, indicating the lower volatility of FAC in the OSG chlorine-treated water. Two types of OSG systems, “Mixed oxidants” and OSG hypochlorite, did not show any significant difference in disinfection, DBPs formation, and chlorine decay rate (paired t-test, p = 0.40, 0.11 ~ 0.70, > 0.42). A significant synergy effect by oxidants other than FAC cannot be expected in the use of “mixed oxidants” at a water treatment plant.

지표수에서 이산화염소 및 염소 복합소독에 의한 트리할로메탄 생성 평가

남숙현,김은주,구재욱,황태문 한국수처리학회 2022 한국수처리학회지 Vol.30 No.6

Due to its synergistic effects, sequential disinfection is considered a viable treatment option for the effective inactivation of pathogenic microorganisms that cannot be treated using the single-step application of chlorine-based disinfectants. This study systematically demonstrated the applicability of sequential disinfection with chlorine dioxide followed by chlorine to control disinfection byproducts. At pH 7,chlorine dioxide/chlorine treatment suppressed the formation of trihalomethanes (THMs) by 10.0% and 25.0% at temperatures of 10℃ and 20℃, respectively, compared to chlorine only. In addition, when using chlorine oxide/chlorine disinfection, a higher pH led to amore significant suppression of THMs production. It was also found that THMs production was lower as the chlorine dioxide dosage increased; in particular, the use of 1.2 mg/L and 5.0 mg/L chlorine dioxide at pH 9 had a substantial suppressive effect on THMs formation, with a reduction of 25.8% compared to chlorine only. Higher temperatures and a higher dissolved organic carbon concentration suppressed the generation of THMs in the chlorine dioxide/chlorine disinfection system compared with the chlorination alone. .

하수의 염소 소독시 총잔류염소 감소 특성에 관한 연구

백영석 ( Young Seog Beck ),손진식 ( Jin Sik Sohn ) 한국물환경학회 2005 한국물환경학회지 Vol.21 No.2

Chlorination of wastewater is recently practiced in Korea. While many researchers have studied the kinetics of aqueous chlorine(HOCl) with nitrogeneous compounds and other organic/inorganic contaminants in drinking water, the researches of wastewater chlorination are relatively few. The purpose of this study was to investigate the chlorine decay kinetics and parameters on wastewater chlorination. Chlorine decay rate increased with increasing initial chlorine concentration. The parameters affecting chlorine decay rate were different in each wastewater treatment plant. One of the most important parameters affecting chlorine decay was initial chlorine concentration, and other parameters such as NH₃-N, total coliform, UV_(254) and Fe were also affected. The decay ratio of chlorine was decreased with increasing initial chlorine concentration, and the disinfection efficiency showed good correlation with the decay ratio.

염소소독에 의한 하수처리장 방류수의 소독부산물 발생에 관한 연구

김증운(Jeung-Woon Kim),송현실(Hyun-SiI Song),배병욱(Byung-Uk Bae) 대전대학교 환경문제연구소 2004 환경문제연구소 논문집 Vol.8 No.-

본 연구에서는 대전광역시 하수종말처리장 4단계 방류수를 대상으로 염소소독 실험을 수행하고 염소 주입농도에 따른 대장균군 및 일반세균의 살균효율과 소독부산물의 생성정도를 조사하였다. 2003년 2월부터 10월까지의 대상하수처리장 4단계 방류수의 대장균군수는 1,100~2,800 개/㎖, 균은 3,500~21,600 개/㎖ 이었으며, 기타 항목별 평균농도는 BOD₅ 10.2, COD_Mn 13.5, SS 7.4 리고 T-N 과 T-P 가 각각 16.243, 0.994 mg/ℓ 이었다. 또한 하수처리장 방류수의 SUVA(specifi absorbance) 값은 2.27 로 친수성, 비방향족, 그리고 저분자량의 물질들로 구성되어 있어 생분해 성이 클 것으로 판단된다. 염소소독 실험결과 pH 7.0, 수온 20±0.5℃ 상태에서 99%이상의 소독을 얻기 위해서는 대장균군의 경우 염소주입농도 1.0 mg/ℓ 에서 10분, 일반세균의 경우 1.0 mg/ℓ 30 분, 2.0 mg/ℓ 에서는 20분, 그리고 3.0mg/ℓ 및 5.0 mg/ℓ 에서는 각각 10분의 접촉시간이 필요한 로 나타났다. 미국의 하수처리장 방류수 대장균군 기준은 1,000 MPN/1OO㎖ 로 염소주입농도 1.0 에서 10분간 접촉시킬 때 이 기준을 만족할 수 있었으며, 이 조건에서 trihalomethanes haloacetonitriles는 검출되지 않았다. pH 7.0, 수온 20±0.5℃, 염소주입농도 20 mg/ℓ, 접촉시 에서 trihalomethanes, haloacetonitriles, 그리고 haloacetic acids의 생성농도는 각각 29.86 그리고 3.1107μg/ℓ 이었으며, chloroform은 22.3467μg/ℓ으로 전체 trihalomethanes의 75.0 내었다. 파과점 염소주입 실험결과, 초기 암모니아성 질소의 농도 1.646 mg/ℓ 의 약 9.1 배까지 염소 입량을 증가시켰을 때 파과점에 도달하였다. 소독부산물의 생성정도는 암모니아성 질소 농도에 반비례하였는데, 암모니아성 질소와 각 소독부산물과의 상관관계(R²)는 trihalomethanes이 O. haloacetonitriles이 0.8169, 그리고 haloacetic acids는 0.7206 이었다. 일반적으로 하수처리는 유기물과 세균이 많기 때문에 높은 농도의 염소소독이 필요할 것이라고 생각되어지나, 본 연구의 결과 수온 및 초기 pH의 영향에 크게 상관없이 소량의 염소주입만으로도 충분한 소독효과를 기대할 수 있었다. 아울러 방류수역의 희석율을 고려하면, 염소소독 후 발생되는 소독부산물은 자체의 휘발과 희석작용에 의해 그 양이 현저히 감소됨으로써 소독부산물이 상수원으로 유입되는 문제는 크지 않을 것으로 판단된다. In Korea, the disinfection of discharged wastewater has become mandatory in 20 municipal wastewater treatment plant (WWTP) have to satisfy the discharge limits. investigate the disinfection efficiency of chlorine and the effect of chlorination on the DBPs (disinfection by-products) in the discharged wastewater. chlorine disinfection conducted. For these purpose, the Daejeon municipal WWTP was selected as a targ water samples were taken from the final sedimentation basin. Based on the experiment the optimum disinfection strategy was proposed, which would satisfy the newly disinfection limits. Typical concentrations of index microorganisms in the discharged wastewater was in the range of 1,100 ~ 2,800 CFU/㎖ for total coliforms and 3,500 ~ 21,600 CFU/㎖ for heterotrophic bacteria. Analysis of other water quality parameters showed that discharged wastewater contained 10.2 mg/ℓ of BOD₅, 13.5 mg/ℓ of COD_Mn, 7.4 mg/ℓ of SS, 16.243 mg/ℓ of T-N, and 0.994 mg/ℓ of T-P The SUVA (specific UV absorbance) value of discharged wastewater was 2.27. This result indicates that the organic component of discharged wastewater is mainly consisted of non-humic substances, which are characterized by hydrophilic, non-aromatic, and low-molecular weights. In the case of total coliforms, the survival rate was 8.9% when 0.5 mg/ℓ of chlorine was contacted for 30 min at pH 7.0, 20±0.5℃. In order to get more than 99% of disinfection efficiency, it was proved that more than 10 min of contact time was required when chlorine dose was 1.0 mg/ℓ. In the case of heterotrophic bacteria, in order to achieve more than 99 % of disinfection efficiency at pH 7.0, 20±0.5℃, the required contact time was 30 min at chlorine dose of 1.0 mg/ℓ, 20 min at 2.0 mg/ℓ, and 10 min at 3.0 mg/ℓ and 5.0, respectively When the discharged wastewater was disinfected with 1.0 mg/ℓ chlorine for 10 min, it was possible to satisfy the U.S. EPA's total coliforms standard (1,000MPN/100㎖). The residual chlorine concentration was 0.42 mg/ℓ in this experimental condition, but both THMs and HANs were not detected probably due to the formation of combined chlorine. When the discharged wastewater was disinfected with 20 mg/ℓ of chlorine for 180 min at pH 7.0, 20±0.5℃, the concentrations of THMs, HANs, and HAAs was 29.8, 2.9, and 3.1 μg/ℓ, respectively. The concentration of chloroform was 22.3467 μg/ℓ, corresponding to 75 % of the total THMs. When the NH₃-N concentration of discharged wastewater was 1.646 mg/ℓ, about 9.1 times of chlorine dosage was required to obtain breakpoint chlorination. It was found that the formation of DBPs was inversely proportional to the concentration of NH₃-N present in wastewater. The correlation coefficient (R²) between NH₃-N and three kinds of DBPs was 0.9647 for THMs, 0.9038 for HANs, and 0.8489 for HAAs, respectively.

염소 바이패스 분진 및 수세 잔류물의 특성분석

이선목,이대근,길준호,이태우,송훈,염우성 한국자원리싸이클링학회 2023 資源 리싸이클링 Vol.32 No.5

염소 바이패스 분진의 주성분은 칼슘, 알칼리 및 염소 성분이며, 시멘트 원료로 재활용하기 위하여 염소 성분 제거가 필요하다. 시멘트업체에서는 염소 바이패스 분진의 시멘트 원료 사용과 KCl 회수를 위해서 수세 처리를 진행하고 있다. 본 연구에서는 염소 바이패스 분진및 수세 잔류물의 재활용 가능성을 파악하기 위해서 35,000톤/년 규모 염소 바이패스 분진 수세 설비에서 사용한 염소 바이패스 분진과 수세 잔류물의 화학성분, 광물 특성 및 미세구조를 분석하였다. 염소 바이패스 분진의 염소 함량은 23.9%에서 수세 처리 후에 1.4%로 감소하여 수세 잔류물의 시멘트 원료 사용 가능성을 확인하였다. 수세 잔류물에서의 염소 성분은 대부분 Calcium Aluminium Oxide Chloride Hydrate 광물 형태로 존재하고 있음을 확인하였다. CaO 성분은 22.4%에서 49.8%로 증가하였으며, K2O 성분은 25.2%에서 5.45% 감소하였다. 수세 잔류물의 평균입경은 22.72μm로 수세 전의 염소 바이패스 분진의 평균입경 12.13μm와 비교하여 크게 증가한 것을 알 수 있는데, 이것은 염소 바이패스 분진에 포함되어있는 1μm 이하의 염소화합물 입자가 수세 과정에서 용해되었기 때문인 것으로 판단되었다. The main components of chlorine bypass dust are calcium, alkali, and chlorine. Chlorine components must be removed from chlorine bypass dust to enable its recycling as a cement raw material. Cement companies usually employ water-washing treatment to recover KCl from chlorine bypass dust. In this study, the chemical composition, mineral properties, and microstructure of the chlorine bypass dust and washed residues obtained from a 35,000 ton/year chlorine-bypass-dust-washing facility were analyzed to determine the feasibility of recycling the dust and its washed residues. The chlorine content of the dust decreased from 23.9% to 1.4% after washing, thus confirming the possibility of using the washed residues as a cement raw material. The CaO component increased from 22.4% to 49.8% whereas the K2O component decreased from 25.2% to 5.45%. The average particle diameter of the water-washed residues was 22.72 μm, which was significantly higher than that of the chlorine bypass dust before washing (12.13 μm). This result was attributed to the dissolution of chlorine compound particles measuring less than 1 μm in the chlorine bypass dust during washing.

전기분해수 살균효과 및 소독부산물 생성 특성 평가

조영만 대한상하수도학회 2013 상하수도학회지 Vol.27 No.5

Chlorine has strong oxidizing power, also it is many advantages over other disinfectants such as the residual characteristic and economic feasibility. However, chlorine also has disadvantages such as creating disinfection by-products of chlorine as THMs. In particular, the most deadly disadvantage of chlorine is that it is extremely poisonous toxins about all alive lives. Disinfection with electrolysis water can be a very useful way Because you do not have to worry about chlorine’s dangerous. In this study, we evaluated the potential as a disinfectant, across the evaluating disinfection effect and generating characteristic of by-products. The electrolyzed water could be obtained removal efficiencies of over 99.9 % the coliform by operating condition such as residence time, current density (voltage), the electrode gap. The residual chlorine be generated 10,000 mg / L in current density 1.0 A/dm2 and residence time of 10 minutes. The residual chlorine concentration was possible to maintain a stable. The by-products generated by high concentration residual chlorine in the reactor such as trihalomethanes, haloaceticacid, chloralhydrate, haloacetonitrile were detected in less than a water quality standards. At the concentration of less than residual chlorine of 1 ppm, the chlorine disinfection by-products be generated most below the detection limit.

염소 함유 클링커의 소성성 및 광물특성에 관한 연구

김태연,김남일,추용식 한국자원리싸이클링학회 2020 資源 리싸이클링 Vol.29 No.6

In this study, raw mix was mixed with CaCl2 for analyzing characteristics of clinker added chlorine and chlorine was added by 2,000ppm at high concentration condition. The raw mix added chlorine was burned at 1250℃~1350℃ and maintained during 10minutes at each maximum temperature. Clinker target modulus was LSF 92, SM 2.5 and IM 1.6 in this study. The burnability of clinker added chlorine was identified by free-CaO content. Free-CaO content decreased as chlorine content increased and free-CaO content of 1350℃-2000ppm clinker decreased by 1.5%. Optical microscope and XRD Analyses were used for identify mineral properties of clinker added chlorine. The mineral of clinker could not be observed at 1250℃ and the size of alite grew larger as chlorine content increased at 1350°C. It showed a good crystallizability as chlorine content increased. As chlorine content of clinker increased, clinker showed a good burnability and mineral property. 본 연구에서는 염소 함유 클링커 특성을 분석하기 위해 raw mix 제조 시 CaCl2를 첨가하였으며, 이때 염소 함량을 고농도 조건인2,000ppm까지 제어하였다. 염소 첨가 raw mix의 소성온도는 1250℃에서 1350℃까지 조정하였으며, 각각의 최대온도에서 10분간 유지하였다. 모듈러스는 LSF-92.0, SM-2.5 및 IM-1.6으로 고정하였으며, 염소 함유 클링커의 소성성은 free-CaO 분석을 통해 확인하였다. 염소 함량 증가에 따라 free-CaO는 감소하였으며, 1350℃-2000ppm의 free-CaO 함량은 1.5%까지 낮아졌다. 염소 함량 증가에 따른 광물특성 확인을 위해 광학현미경 및 XRD를 활용하였다. 1250℃ 소성 시에는 클링커 광물을 관찰할 수 없었으며, 1350℃ 소성 시에는 염소함량 증가에 따라 alite 크기가 소폭 증가하였다. 또한 염소 함량 증가에 따라 우수한 광물결정성을 발현되어 클링커 내 염소함량이 증가할수록 우수한 소성성 및 광물특성을 보였다.

수온 변화에 따른 상수관망 내 수질반응계수 추정 및 월별 잔류염소농도 분포 변화 분석

정기문,최태호,강두선,이주원,황태문 한국수자원학회 2023 한국수자원학회논문집 Vol.56 No.11

국내에서는 지속적인 상수도 수질사고 발생으로 인해 수돗물 수질에 대한 이용자 불신이 확산되고 있다. 특히, 수질사고 외에도 수돗물에 포함된 염소 성분 등으로 인해 맛, 냄새 등에 대한 이용자들의 수질민원 또한 지속적으로 발생하고 있다. 따라서 상수도 사업자들은 이용자에게 공급되는 잔류염소농도가 충분히 잔류하면서도 과도하게 유지되지 않도록, 시간적(Scheduling) 및 공간적(Rechlorination) 관점에서 상수관망 내 잔류염소농도가 균등하게 분포하도록 다양한 방법을 검토 및 적용하고 있다. 본 연구에서는 상수관망 해석을 통한 월별 잔류염소농도 최적 관리 방법의 일환으로, 대규모 상수관망시스템을 대상으로 Lab-scale 실험을 통한 수체반응계수, EPANET 수질해석을 통한 관체반응계수 등 관망 수질반응계수를 온도별로 추정하고, 온도별 수질반응계수를 바탕으로 염소투입농도 조건에 따른 월별 잔류염소농도 분포 현황을 분석하였다. 분석 결과, 온도 조건이 달라짐에 따라 잔류염소농도 하한 및 상한기준을 만족시킬 수 있는 효율적인 염소투입농도 조건 또한 달라지므로, 월별 잔류염소농도의 공간적 분포를 고려하여 구체적이고 정량적인 염소투입 계획 수립이 필요한 것으로 판단된다. In South Korea, ongoing incidents related to drinking water quality have eroded consumer trust. Specifically, beyond quality incidents, there have been complaints about taste, odor, and other issues stemming from the presence of chlorine. To address this, water service operators are employing various management strategies from both temporal (scheduling) and spatial (rechlorination) perspectives to ensure uniform and safe distribution of chlorine residuals. In this study, we focus on the optimal monthly management of chlorine residuals, based on water distribution network analysis. Water quality reaction coefficients, including bulk fluid and wall reaction coefficients, were estimated through lab-scale tests and EPANET water quality simulations, respectively, accounting for temperature variations in a large-scale water distribution network. Utilizing these estimated coefficients, we examined the monthly variations in chlorine residual distribution under different chlorine injection conditions. The results indicate that the efficient concentration for chlorine injection, which satisfies the residual chlorine limit range, varies with temperature changes. Consequently, it is imperative to establish a specific and quantitative chlorine injection plan that considers the accurate spatial distribution of monthly chlorine residuals.