ASSESSMENT OF DISINFECTION BY PRODUCT AND EVALUATION OF WATER DISTRIBUTION SYSTEM USING WAT PRO& WATER GEMS SOFTWARE: CASE STUDY OF JIMMA CITY, ETHIOPIA

Abstract

Disinfection, water quality and water supply distribution system are an important parameters that could affect water companies and their consumers in worldwide. The effect of Water quality and unbalanced addition of disinfectant which affects the health of water and its distribution network are common problems that most African community encounter. The major goal of this study was to evaluate the hydraulic performance of the water distribution network and the level of disinfection by product at Jimma water treatment plant using wat-pro and water-Gems software. The findings indicate that giardia and virus percent are reduced by 23.5 % and 76.26 % respectively; so these indicate the water quality is poor according to the standard. Chlorine is by product from the disinfectant; due to its unbalanced dosage it can form disinfection by products, which are nasty and can increase a risk of bladder cancer and other adverse consequences on human health after a long period of time. At the design period of 2019, the study area's maximum daily demand is calculated as 30,310m3/day but the source maximum yield is only 27,000 m3 per day, therefore the existing water distribution system cannot be considered sustainable. According to the simulation's results for the current extended time at peak hour flow, the hydraulic parameters performance is 26.59% for (<0.6 m/s) which is at 7:00 AM, but most of the distribution pipelines has the optimum range 64.43% for (0.6 to 2 m/s), 2.88% for (2 to 2.5) m/s, and 6.07% for (>2.5 m/s) higher velocity ranges. While the low hour flow hydraulic parameters performance is 49.74% for (>-5m) for lowest pressure range; 16.29% for (-5 to15 m); 32.07% for (15 to 70 m) and 1.88% for (≥70 m) higher pressure ranges which is at 2:00 AM. The pressure performance index was under 50% (half), but due to the acceptable velocity performance index, the hydraulic performance index became 0.38 which is within the permissible standard. The above results show that the percent reduction of giardia and virus is under the standard value and the performance of the distribution pipelines coverage percent of jimma is little and less than half percent. So the town's current water removal efficiency and the distribution network are underperforming and do not adequately supply water to the various demand categories. Therefore, the existing disinfection by product and distribution system of Jimma town is notsustainable. To increase the sustainability improving the disinfection by product and finding additional source of water for areas which the town treatment plant can’t reach should be mandatory.