Water Treatment

Optimizing the water distribution network of community water supply using different computer simulation techniques

2023-01-01T00:00:00Z

Optimizing the water distribution network of community water supply using different computer simulation techniques Sutharsan, M.E. The appropriate operation of a water distribution network (WDN) of any water supply scheme is vital to supply sufficient potable water to consumers at sufficient pressure. However, the performance of the WDN may vary from the original design in the long run. In this study, a WDN network model was built using WaterGEMS and WaterCAD computer simulators, and hydraulic analyses were conducted to obtain an optimal WDN for a community water supply scheme of a village in Sri Lanka. A series of steps such as; selection of models, network representation, simulation of network, problem identification, network configuration finalization, and results analysis were carried out in developing the WDN simulation model. The hydraulic parameters such as pressure, flow velocity, and flow rate were analyzed under extended period simulation. The result indicated that the nodal pressure head in the junctions (100%) is above the required pressure level of 10 meters H2O, which is adequate for the effective performance of the water distribution system (WDS) during peak and off-peak demand hours. The elevated water tower was optimized with a 10 m height to supply water at satisfactory pressure. Nodal pressure is negatively correlated with ground elevation. The flow velocity was observed within the range of 0.1-0.4 m/s in 67% of the pipe network, while 17% of the pipe network velocity was below 0.1 m/s. The low daily water demand of the small community could be the reason for the low-velocity scenario, which shall lead to silt deposition in the pipelines; hence frequent line washout to eliminate the silt deposition in the system is recommended. The WDN was designed for optimized pipe sizes with availability in the market.

Performance evaluation of slow sand filter after pretreated with coagulant chemical in Kilinochchi wtp

2022-01-01T00:00:00Z

Performance evaluation of slow sand filter after pretreated with coagulant chemical in Kilinochchi wtp Anoja, N.; Thadshagini, R.; Thushyanthy, M. The Kilinochchi water treatment plant (KWTP) which has a Roughing Filter, an Aerator and Slow Sand Filters (SSF-KWTP) had been designed to meet the increasing water demand of Kilinochchi district. The Source for the KWTP is Dry Aru which is fed by Iranamadhu reservoir. Huge seasonal fluctuation of turbidity and the algal population in Dry Aru affect the performance of the KWTP and the plant shut down for several months. The decision has been taken to incorporate the coagulation flocculation treatment system to KWTP to improve the treatment efficiency. Slow sand filtration works primarily through biological activity on the sand bed and it is a chemical free treatment system. Adding pre-treatment chemical may affect the biofilm layer as well as the performance of the slow sand filter. Hence the purpose of the study is to evaluate the filtration efficiency of the slow sand filter after pretreatment with poly aluminium chloride (PACL) coagulant chemical. Real Slow sand filter model (SSF-Model) has been built and connected with coagulation flocculation system. Turbidity reduction percentage of the SSF-Model and SSF-KWTP was in the range of 75 97.05% and 90.63-97.30% respectively. Average colour reduction % of the SSF-Model was 83.87%. Algal removal efficiency of the SSF-Model was 58% and the SSF-KWTP was 63.7%. There was no significant difference in performance of SSF-Model in terms of Turbidity (4%), Manganese (3.9%), Total iron (0.4%) and Algal removal (5.6%) efficiency compared with the SSF-KWTP. Colour removal efficiency (14%) of SSF-Model was significantly lower than SSF-KWTP. It can be concluded that coagulation flocculation treatment system with pretreatment chemical as PACL can be incorporated to improve the treatment efficiency to KWTP.

Analysis of residual Chlorine concentration in water distribution system in Vavuniya District

2020-01-01T00:00:00Z

Analysis of residual Chlorine concentration in water distribution system in Vavuniya District Thinarthika, T.; Thushyanthy, M.; Prabhaharan, M.; Saravanan, S.; Per Aru reservoir is located in Vavuniya District and water from the reservoir is treated through the water treatment plant. Chlorine is used as a disinfectant and it should ensure that there is a constant minimum residual chlorine level (RCL) in all the parts of a distribution system. Further, the factors that influence chlorine decay should be identified. On this basis, the study was aimed to analyze the RCL concentration along the distribution system and find the locations with lower RCL Concentration than the acceptable range (0.2 - 0.5 mg/L) and possible reasons for lower concentrations. A field study was conducted at the water distribution system connected to the Marakkarampalai overhead tank by collecting water samples at different locations. Totally 31 locations in the distribution system were selected. Water samples were analyzed for RCL concentration, pH, dissolved oxygen (DO) and temperature at the site itself. Collected data on RCL were statistically analyzed with one sample t-test, paired t-test and Duncan multiple range test. Information on the water distribution system; age of the pipe, pipe materials and diameter and distance from the overhead tank was collected. Results revealed that there was no significant difference in RCL concentration measured in different time periods however a significant difference was observed among the data collection points on the same day. The RCL concentration among the Marakkarampalai distribution system varied from 0 mg/L to 1.01 mg/L. Pattanichurpuliyankulam and Thirunavatkulam areas showed very low RCL concentration. Temperature of the collected water sample varies from 27.4 °C to 33.8 °C. Temperature range from 31 °C to 32 °C shows the acceptable RCL concentration. Higher temperature causes high RCL decaying which results in low RCL in consuming water. The pH and DO do not influence on RCL in consuming water. There was no any clear relationship recorded for pH and DO against RCL. Pipe age, Pipe material and Pipe diameter have no influence on residual chlorine decaying in this distribution system. Further, nearby areas to the overhead tank show a sufficient amount of RCL in consuming water. However, the areas which are far away from the overhead tank and complex designed areas show a lower amount of RCL in consuming water. Hence, actions need to be taken to ensure drinking water supply with an acceptable range of chlorine in this water distribution system.

Evaluation of the microbial and coliform contamination during dry and rainy seasons in water samples collected from some selected hospitals

2008-01-01T00:00:00Z

Evaluation of the microbial and coliform contamination during dry and rainy seasons in water samples collected from some selected hospitals Birunthai, R.; Kirupahari, S.; Vasantharaba, S.; Balakumar, S.; Arasaratnam, V. he greatest risk from microbes in water is associated with consumption of drinking-water that is contaminated with human and animal excreta, although other sources and routes of exposure may also be significant. The aims of the present studies were to evaluate the microbial contamination of drinking water and the examination of the coliform occurrence in some selected hospitals during dry and wet seasons. For this study one General hospital, one Base Hospital and three District Hospitals situated in Jaffna peninsula were selected. General Hospital, obtains the water supply through municipal council and from one of the well situated in the hospital. Water from municipal counes supply contaminated statistically non significant (p>0.05) number of cells during dry season than the standard level prescribed by Sri Lankan Standard (100 colonies/mL) and contained more counts during wet season. The well water supply contained statistically significant (p<0.05) number of cells during dry and wet seasons. In Base Hospital, there is one dug well and three tube wells. Dug well water and tube wells water contained statistically significant (p<0.05) number of cells during both seasons than that defined by Sri Lankan Standard. Of the three District Hospitals, in the first hospital (Hospital C, there is one dug well dug well and a tube well. Both water supplies for drinking purpose contained significantly (p<0.05) high number of aerobes during dry season and wet season. In the second District hospital (Hospital D), Water for human consumption is obtained from water board supply and Rain water harvest. The water supplied by water board contained statistically non supuificant (p>0.05) amount of acrobes than the standard level during dry season and statistically significant (p>0.05) during wet season while the rain water harvest contained the aerobic contamination lower than that prescribed by Sri Lankan Standard during dry season and had non significant (p>0.05) amount of aerobic contamination during wet season. In District Hospital 3 (Hospital E), the water sample contained statistically significant (p<0.05) number of counts than the standard level during both seasons. The water samples collected from all the hospitals from different sites contained no anaerobic bacterial contamination. In coliform presumptive test analysis, in General Hospital positive result observed during both seasons in well water supply, in Base Hospital during wet season positive result were observe in all well water samples, in District Hospital 1 (Hospital C) positive result observed in canteen supply during dry season while tube well supply showed positive results during wet season, in District Hospital 2 (Hospital D) no positive results were observed during both seasons, positive results were observed in the well water sample in District Hospital 3 (Hospital E during wet season. In all the weater samples the pH ranged from714-7.68 during dry season while 6.76-7.44 during wet season. Water samples did not show any signified optical density at 550 and 600 mm.