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.
