Objectives : The purpose of this study is to suggest operating conditions that can minimize the disinfection by-products of sodium hypochlorite produced in on-site sodium hypochlorite generators.Methods : The characteristics of disinfection by-products were investigated by operating conditions (dissolved water type, brine concentration, temperature of electrolytic cell inflow water, pH of electrolytic cell inflow water and electrolyzer current density) using a on-site sodium hypochlorite generator(5 kg/day).Results and Discussion : The concentration of disinfection by-products (chlorate, bromate) according to the type of dissolved water was found to be high in the order of softened water > tap water > RO treated water. As the brine concentration increased, chlorate decreased and bromate increased. The optimal saline concentration was found to be 3% or more. As temperature of electrolytic cell inflow water increases,, chlorate decreases and bromate increases. The difference in the concentration of disinfection by-products(chlorate, bromate) according to the pH of electrolytic cell inflow water is not large, and the appropriate pH is determined to be about 7 when the free available chlorine and disinfection by-products are taken into account. Also, as the current density increases, the chlorate increases and bromate showed a decreasing trend.Conclusion : It has been shown that the concentration of disinfection by-products can be minimized when operating within the operating range suggested by the on-site sodium hypochlorite generator manufacturer, and some operating conditions are thought to have been suggested by the manufacturer to protect the electrolyzer cells. As the market for on-site sodium hypochorite generator gradually expands, it is expected that improved facilities will be continuously released in consideration of the stricter standards for disinfection by-products.
Objectives : This study was conducted to suggest field operating conditions that can minimize disinfection by-products for three types of sodium hypochlorite.Methods : In this study, changes in free available chlorine, chlorate and bromate were analyzed according to storage temperature, storage time and presence or absence of sunlight for three types of sodium hypochlorite(two types of bleach and one type of sodium hypochlorite made on-site hypochlorite generator).Results and Discussion : In the case of bleach with 12% free available chlorine, when operating with a target of 10% of more of free available chlorine, the storage time for each storage temperature was 3 days at 40℃, 13 days at 30℃, 27 days at 20℃, 85 days at 10℃, and 200 days at 5℃. In the case of bleach with 5% free available chlorine, when operating with a target of 4% of more of free available chlorine, the storage time for each storage temperature was 37 days at 35℃, 255 days at 20℃, 1,343 days at 10℃, and 4,821 days at 4℃. In the case of sodium hypochlorite with 0.8% free available chlorine made on-site hypochlorite generator, when operating with a target of 0.7% of more of free available chlorine, the storage time for each storage temperature was 10 days at 3 5℃, 42 days at 20℃, 470 days at 10℃, and 1,770 days at 4°C. As a result of evaluating the quality change according to the presence or absence of UV protection, the free available chlorine decreased rapidly when exposed to sunlight, whereas the free available chlorine decreased slowly in the case of indoor storage.Conclusion : Bleach with 12% free available chlorine can be stored for about 60 days at 15℃, and bleach with 5% free available chlorine can be used within about 6 months at 15℃. And sodium hypochlorite with 0.8% free available chlorine can be used within 10 days at room temperature. In addition, when storing sodium hypochlorite, it is suggested that it be stored indoors protected from sunlight.
Objectives : The objectives of this study are to assess the degree of uniformity of the flow rate flowing into four grit chamber for actual waste water treatment and to to improve hydraulic structure of the existing distribution channel.Methods : Mobile ultrasonic flow meter was used to measure each flow rate flowing into four grit chambers, and the CFD technique was used to suggest several hydraulic structure improvements for enhancing flow rate evenness.Results and Discussion : From the results of the actual measurement using ultrasonic flowmeter and CFD simulation, The flow rates distributed to four grit chamber through the existing complicated open channels (four outlets) showed a severe unevenness. It was revealed that the flow rate passing through the outlets 1 and 4 at both right anf left ends showed a difference of more than 20% compared to those through outlets 2 and 3 installed in the center.Conclusion : As a result of examining the data of the water level, flow rate, and distribution percentages passing through the 4 distribution channels using the CFD simulation, it was found that case 4 (the case to install the orifice walls on both sides) had the most even flow rate distribution effect. However, as a result of comparing the water levels in case 4 and case 6, the case installing both orifice walls make relatively higher head loss.
Objectives : This study attempted to investigated the advantages that can be obtained by applying the concept of ‘Eulerian path’ called ‘one-touch drawing’ to the block type water supply network which actually has been operating in Korea.Methods : This study applied the ‘Eulerian path’ concept to an actual water supply network, and suggested simple C language program for searching adjacency matrix. Five Eulerian path based design scenarios were derived using the C language program. The pressure and residual chlorine distribution pattern of five design scenarios and the existing small block network were simulated using EPANET and compared each other. Also, by comparing all scenarios construction costs, the economic feasibility related to initial investment cost was reviewed.Results and Discussion : Five Eulerian path scenarios with two or more closed pipe loops were suggested using the C language program checking out adjacency matrix. One of them(scenario 5) consists of 7 closed pipes that can supply water to all nodes even if the number of pipes is reduced by about 10, and an increase in residual chlorine concentration of about 0.01 mg/L can be predicted at each node. In addition, it is expected that the initial investment cost of Scenario 5 can be reduced by about 23%, compared to the initial investment cost of the existing small block.Conclusion : Therefore, by applying the concept of an Eulerian path to the design of a water supply pipe network, it is possible to economically eliminate meaningless pipes while maintaining the redundancy of water supply.
Objectives : In this study, the concept of the Eulerian path, which has already been proposed as a solution to the problem of head loss and residual chlorine reduction caused by complexity of nodes and pipelines, and the non-Euerian path proposed in this study were compared and their feasibility were examined.Methods : The concepts of ‘removal of odd nodes’, ‘removal of 3-intersection nodes’, and ‘removal of zero demand nodes’ were applied to the virtual water supply networks, and the number of cases were analyzed and evaluated from the viewpoint of configuration complexity and hydraulic efficiency. For Euler graph and non-Euler graph water supply networks, each total pipe length, number of removal pipes, pressure head and flow rate were simulated with EPANET2 program.Results and Discussion : As a result of simplifying and designing new output networks for virtual Euler and non-Euler graph, it was revealed that the concept of ‘removing a 3-intersection nodes’ could be the most efficient by removing more pipes. However, in terms of configuring the output network as an Euler graph, the concept of ‘removing odd nodes’ can be considered more reasonable.Conclusion : It is difficult to configuring watersupply network as a perfect Euler graph. Therefore, the application of the concept of removing odd nodes suggested in this study can promote efficient simplification of the network. In addition, it can be thought that the application of this concept can expect efficiency in terms of hydraulics and water quality.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.