Quality Assessment of Sokoto Water Distribution Networks

Abstract

The research is on the quality assessment of Sokoto water distribution networks. Sample coordinates of the study area were taken using GPS, the experiments were carried out at different consumer locations with thirty (30) samples of water collected weekly for four (4) weeks, to determine various purification parameters that are related to both bulk (kb) and wall (KW) reactions coefficients for Sokoto water distribution pipe network, these include residual chlorine, pH, dissolved oxygen (DO), temperature and conductivity. pH, dissolved oxygen (DO) and conductivity have average values ranging from 6.7 to 7.5; 1.1 to 6.5ppm; 310 to 520 μs/cm respectively and conform to the Nigerian Standard for Drinking Water Quality (NSDWQ), except temperature which has the average values between 29 oC, and 32.6oC, and the individual values between 26 oC, and 38.4oC, chlorine residual average values obtained, ranging from 0.11mg/l to 0.26mg/l with the lowest individual value obtained being 0.011mg/l. The age of water supply from the treatment plants in the distribution network is 6 hours and both first and second-order decay reactions were ascertained from the graph and first-order decay having the highest number of occurrences was used in Epanet 2.0 water quality modeling. The kb values ranged from 0.0025 to 0.013md-1. A total of 86 out of the 120 samples, which constitute 71.7% were straight lines which indicate first-order and thus, the average kb was determined to be 0.006/day (0.144/hour).  It was observed that of all the 120 samples examined in the study, chlorine reaction with natural organic matter (NOM) was small. The average kw for Sokoto WDS was deduced to be 0.078m/h, considering, the following steel pipe conditions used in the network area. kW (ft/h), -α =-38.5, H-W C=150, kW = 38.5/150 = 0.257ft/h = 0.078m/h (-0.078m/h).