Microbiological Assessment and Treatment of Drinking Water Using Zinc Oxide Nanostructure in Khartoum, Sudan

Abstract

In this study, biological characteristics of drinking water were evaluated by purification method using ZnO nano structure as photo catalyst. Collection of 196 samples of water was carried out during January 2019-December 2019, covering three different seasons i.e. Autumn, Winter and Summer.  Study area consisted of four lines of the Khartoum network according to (GPS) map. Samples were examined microbiologically to determine Total Coliform Count (TCC) by Most Probable Number (MPN) technique and fecal coliform (E. coli). ZnO semiconductor nanostructure was prepared and characterized using Scanning Electron Microscopy (SEM), Ultra Violet (UV) and X-Ray Diffraction (XRD) techniques. Microbiological analysis indicated that 66% and 37% of the samples tested were contaminated by Total and fecal coliforms, respectively. The highest Total Coliform contamination level (85.7%) was recorded in August during rainy season.  While, during others seasons, the contamination levels were in the range of 39 - 82%.  As for the water samples collected from different lines, highest level of contamination (100%) by total coliforms was recorded for line one, two and three in Winter.  However, the lowest contamination level (28%) was recorded for line four in Winter.  Fecal contamination was more frequently detected during rainy season in line one (100%), followed by line two and four (85%), while it was 57% in line three. In remaining seasons, the contamination levels were in the range of 14-71%, respectively. Almost 100% removal of E. coli was achieved by using only 0.01gm /100ml of ZnO nanostructure within 90 minutes in sunlight and the minimum bacterial contact time for removal was found to be 20minutes at 0.05gm/100 ml and 0.01gm/100 ml within 90 minutes in the dark. This study concluded that Khartoum drinking water was highly contaminated with total coliform and E. coli, and the contamination in rainy season was the highest.It is further concluded that the higher degradation percent of E.coli was achieved by ZnO catalyst in sun light.