I 정수장의 UV 공정 적용을 통한 소독능 제고 및 관망 잔류염소 적정 운영 효과 예측

박종일(Jong-Il Park),이영(Young Lee),김건회(Keon-Hoi Kim),이태훈(Tae-Hoon Lee),박철종(Cheol-Jong Park),유정희(Jeong-Hee Yoo) 대한환경공학회 2019 대한환경공학회지 Vol.41 No.11

목적 : 본 연구에서는 I정수장에 고도공정으로 도입된 UV 공정을 활용한 소독능 제고 및 관망 잔류염소 적정 운영효과를 분석하였다. 방법 : Virus 및 Giardia 불활성화비 계산은 환경부에서 개발한 “소독능 계산 프로그램”을 활용하였으며, 수질인자(잔류염소, 수온 등)는 자동측정기로 측정 및 저장하였다. 동절기 최악 수질 조건 시 용수생산량별 Giardia 불활성화비 1.1 이상 만족을 위한 정수지 잔류염소 농도를 산정하고, EPANET2.0을 통해 해당 조건에서의 공급과정 잔류염소 농도를 모의하였다. I정수장 UV 설비의 UV 조사량 인증 시험은 UVDGM 2006에 의거하여 HDR|HydroQual에서 수행하였다. UV 소독 적용시의 Giardia 불활성화비를 도출한 후, 공급과정 잔류염소 적정 운영을 위한 정수지 잔류염소 농도를 산정하였다. 염소 단독 소독과 UV 병행 소독 시의 약품비 및 전력비를 통해 원단위를 산출하여 경제성을 비교하였다. 결과 및 토의 : I정수장에서 염소 단독 소독으로 동절기시 Giardia 불활성화비 1.1 이상 달성을 위해서는 정수지 잔류염소 농도를 0.73-1.59 mg/L로 운영하여야 하는 것으로 산정되었다. 이 경우 관말 배수지 잔류염소 농도는 0.63-1.42 mg/L로 나타났다. I정수장의 UV 설비를 소독에 적용할 경우, 반응조당 1개 섹션을 가동전력 100%로 운영 시 인증조사량(VD)은 21.3 mJ/cm²로 도출되었다. 이는 Giardia 불활성화비 1.936, Cryptosporidium 불활성화비 1.775에 해당하는 값이었다. 이를 통하여 UV 소독으로 Giardia 및 Cryptosporidium의 안정적인 소독이 가능할 것으로 사료되었다. 또한 UV 소독 적용 시 정수지 잔류염소는 0.59-0.65 mg/L (관말 배수지 잔류염소 농도 0.5 mg/L 유지 수준)로 운영할 수 있다고 산정되었다. 경제성 분석 결과, 용수생산량 190,000-250,000 m³/일인 경우 UV 소독을 병행하면 NaOCl 단독 소독 대비 원단위를 0.02-0.85 원/m³ 절감할 수 있을 것으로 예상되었다. 결론 : I정수장 UV 공정 적용 시 높은 소독 효율 확보와 정수지 및 관망 잔류염소 농도의 적정 운영이 가능할 것으로 판단되었다. 이를 통하여 약품비의 절감은 물론 소독부산물 발생 농도 저감이 예상되었다. 또한, UV의 Giardia 및 Cryptosporidium에 대한 소독효과가 높아 기존의 염소소독을 효과적으로 보완할 수 있을 것으로 기대되었다. Objectives : In this study, disinfection efficiency improvement and optimal operation of residual chlorine were analyzed when apply UV (Ultraviolet) process in I WTP (Water Treatment Plant). Methods : Inactivation ratios of virus and Giardia were calculated by “Disinfection efficiency calculation program” which was made by Ministry of Environment. Water quality factors (residual chlorine, temperature, etc) were measured and saved by auto measuring instruments. Residual chlorine in clean water reservoir was calculated for satisfy the inactivation ratio of Giardia over 1.1 at worst case of water quality condition in winter season. Residual chlorine in distribution reservoir was simulated by EPANET2.0. UV dose validation test of UV facilities in I WTP was conducted by HDR|HydroQual according to UVDGM (Ultraviolet Disinfection Guidance Manual) 2006 of US EPA (United States Environmental Protection Agency). Inactivation ratio of Giardia by application of UV disinfection and optimal concentration of residual chlorine in clean water reservoir for optimal operation of water distribution line were calculated. Economical efficiency was compared by price unit of chlorine sole disinfection and UV combined disinfection. Results and Discussion : In order to satisfy the inactivation ratio of Giardia over 1.1 by chlorine sole disinfection, residual chlorine in clean water reservoir should be operated within 0.73-1.59 mg/L. In this case, residual chlorine of distribution reservoir at the end of water distribution line was 0.63-1.42 mg/L. If UV process of I WTP was applied to disinfection, validation dose (VD) would be estimated 21.3 mJ/cm² when operating 1 section per reactor at 100% ballistic power level. Which value corresponded to inactivation ratio of Giardia 1.936 and Cryptosporidium 1.775. Through this, it would be possible to secure effective disinfection of Giardia and Cryptosporidium, and reduce post chlorine injection. In application of UV disinfection, residual chlorine in clean water reservoir could be operated within 0.59-0.65 mg/L (residual chlorine in distribution reservoir at the end of distribution line would be 0.5 mg/L level). By the result of economical efficiency analysis, when water production is 190,000-250,000 m³/d, UV combined disinfection would be saved the price unit within 0.02-0.85 KRW/m³ comparing with chlorine (NaOCl) sole disinfection. Conclusions : If UV process in I WTP was applied to disinfection, it would be possible to secure high disinfection efficiency and optimal operation of residual chlorine in clean water reservoir and distribution line. Through this, it would be expected to economize chemical costs and decrease the concentration of disinfection byproducts. In addition, UV has high disinfection effect against Giardia and Cryptosporidium, it would be expected to effectively complement the chlorine sole disinfection.

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. .

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.

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.

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.

고상염소 소독장치의 잔류염소 농도 변화에 관한 연구

김용철 ( Yong Cheol Kim ),이택순 ( Taek Soon Lee ),전준호 ( Jun Ho Jeon ),한치복 ( Chi Bok Han ) 한국수처리학회 2016 한국수처리학회지 Vol.24 No.4

This study was to suggest the appropriate use of water disinfection equipment by using calcium hypochlorous acid [Ca(OCl)₂] as a disinfectant. The experimental disinfection equipment consists of polypropylene filter and acrylic housing. The housing has six holes to adjust disinfective solution’s volume. The disinfection equipment was installed in water tank(1 ton). The principle of disinfection equipment is that disinfective solution dissolved in PP filter was spilled outside through housing’s hole and diffused in water tank. In case of steady state (closed system), optical disinfectant dose was 20 g in Water tank(1 ton). In case of unsteady state (water supply and outflow condition were applied), optical disinfectant dose was 40 g in water tank(1 ton). The experimental disinfection equipment is proved to be able to control the residual chlorine concentration in water tank by adjusting disinfectant’dose.

전기분해 염소소독공정의 반응표면분석법을 이용한 차아염소산나트륨 발생 최적화

주재현(Jaehyun Ju),박찬규(Chan-gyu Park) 한국환경보건학회 2022 한국환경보건학회지 Vol.48 No.3

Background: Disinfection is essential to provide drinking water from a water source. The disinfection process mainly consists of the use of chlorine and ozone, but when chlorine is used as a disinfectant, the problem of disinfection by-products arises. In order to resolve the issue of disinfection by-products, electro-chlorination technology that produces chlorine-based disinfectants from salt water through electrochemical principles should be applied. Objectives: This study surveys the possibility of optimally producing active chlorine from synthetic NaCl solutions using an electro-chlorination system through RSM. Methods: Response surface methodology (RSM) has been used for modeling and optimizing a variety of water and wastewater treatment processes. This study surveys the possibility of optimally producing active chlorine from synthetic saline solutions using electrolysis through RSM. Various operating parameters, such as distance of electrodes, sodium chloride concentration, electrical potential, and electrolysis time were evaluated. Results: Various operating parameters, such as distance of electrodes, sodium chloride concentration, electrical potential, and electrolysis time were evaluated. A central composite design (CCD) was applied to determine the optimal experimental factors for chlorine production. Conclusions: The concentration of the synthetic NaCl solution and the distance between electrodes had the greatest influence on the generation of hypochlorite disinfectant. The closer the distance between the electrodes and the higher the concentration of the synthetic NaCl solution, the more hypochlorous acid disinfectant was produced.

정수처리를 위한 전기분해 적용시 잔류염소 생성에 관한 연구

문백수 ( Bag Sou Moon ),황태문 ( Tae Mun Hwang ) 한국수처리학회 2015 한국수처리학회지 Vol.23 No.1

There are increased activities in development and application of directly electrolysed water using the natural chloride content for disinfectants production. Free chlorine produced with electrolysis water can be a very useful disinfectant for the removing pathogen microorganism. The present works presents the evaluation of free chlorine generation and THMs characteristics during and after electrolysis. All electrodes were titanuim based insoluble materials and rectangular plate with an effective area of 50 ㎝×20 ㎝. Electrolysis reactor composed of the six negative electrodes and the five positive electrodes. Directly electrolysis reaction using the natural chlorine content in sand filtered water generated the free chlorine for feasible disinfectant. The residual chlorine be generated 1.0 ㎎/L in current density 3.8 A/㎠ and flow 5.0 L/min. the generated free chlorine concentration was stable. Electricity was exponentially increased with flow increment for the chlorine formation. Specific chlorine value which means the generated chlorine rate per current density was 1.60 at the flow of 15 L/min. Chlorine concentration of 1 ㎎/L was stably generated above 1.0 current density and below 30 sec retention time for chlorination concentration of 1 ㎎/L. The by-products generated by high concentration residual chlorine in the reactor such as trihalomethanes were detected in less than a water quality standards.

해수에서의 소독제 거동 예측 모델에 관한 연구

한지희,손진식 대한상하수도학회 2016 상하수도학회지 Vol.30 No.1

Disinfectant/oxidation process is a crucial process in water treatment for supplying safe drinking water. Chlorination is still widely used for water treatment area due to its effectiveness on microbial inactivation and economic feasibility. Recently, disinfection concern in marine environment is increasing, for example, movement of hazardous marine organism due to ballast water, marine environmental degradation due to power plant cooling water discharge, and increase of the amount of disinfectant in the offshore plant. It is needed to conduct the assessment of disinfectant behavior and the development of disinfectant prediction model in seawater. The appropriate prediction model for disinfectant behavior is not yet provided. The objective of the study is to develop chlorine decay model in seawater. Various model types were applied to develop the seawater chlorine decay model, such as first order decay model, EPA model, and two-phase model. The model simulation indicated that chlorine decay in seawater is influenced by both organic and inorganic matter in seawater. While inorganic matter has a negative correlation with the chlorine decay, organic matter has a positive correlation with the chlorine decay.

Reflection on Kinetic Models to the Chlorine Disinfection for Drinking Water Production

Yoon-jinLee,Sang-hoNam 한국미생물학회 2002 The journal of microbiology Vol.40 No.2

Experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform used as a general indicator organism based on the chlorine residuals as a disinfectant. The water samples were taken from the outlet of a settling basin in a conventional surface water treatment system that is provided with the raw water drawn from the mid-stream of the Han River. The inactivation of total coliform was experimentally analyzed for the dose of disinfectant, contact time, filtration and mixing intensity. The curves obtained from a series of batch processes were shaped with a general tailing-off and biphasic mode of inactivation, i.e. a sharp loss of bacterial viability within 15 min followed by an extended phase. In order to observe the effect of carry-over suspended solids on chlorine consumption and disinfection efficiency, the water samples were filtered, prior to inoculation with coliforms, with membranes of both 2.5 mm and 11.0 mm pore size, and with a sand filter of 1.0 mm in effective size and of 1.4 in uniformity coefficient. As far as the disinfection efficiency is concerned, there were no significant differences. The parameters estimated by the models of Chick-Watson, Hom and Selleck from our experimental data obtained within 120 min are: log(N/N0)=-0.16CT with n=1, log(N/N0)=-0.71C0.87T with n1 for the Chick-Watson model, log (N/N0)=-1.87C0.47T0.36 for the Hom model, log (N/N0)=-2.13log (1+CT/0.11) for the Selleck model. It is notable that among the models reviewed with regard to the experimental data obtained, the Selleck model appeared to most closely resemble the total coliform survival curve.