<b>Background:</b> Shallow wells and boreholes are vital sources of potable water in Hargeisa. This water can be polluted by runoff, in particular during the rainy season, causing outbreaks of waterborne i...<b>Background:</b> Shallow wells and boreholes are vital sources of potable water in Hargeisa. This water can be polluted by runoff, in particular during the rainy season, causing outbreaks of waterborne infections. <b>Objectives:</b> This research aimed at evaluating the microbial quality of shallow wells and boreholes water around Hargeisa, Somaliland. <b>Methods:</b> The total coliform and <i>Escherichia coli</i> count were done by using the membrane filtration method. Overall, 100 ml of each water sample was filtered via a 0.45 μm membrane filter, and then the filters were put on m-Endo agar plates that were incubated at 37°C for 24 to 48 hours. <b>Results:</b> The mean value of total coliform counts for the boreholes and shallow wells ranged from 1.288 × 10<sup>3</sup> to 8.8 × 10<sup>3</sup> CFU/100ml, while the mean value of total <i>E. coli</i> counts also ranged from 3.5 × 10<sup>2</sup> to 4.429 × 10<sup>3</sup> CFU/100ml. Results from this study have demonstrated that all water sources (Arabsiyo, Dararweyne, Darasalaam, Dabaraqas, and Jaleelo) don’t comply with the WHO guideline for drinking water. Results from the analysis of water samples of 28 wells demonstrated a significant correlation between total coliform and <i>E. coli</i> counts (P = 0.01). Therefore, this water is not fit for human consumption unless it is treated. <b>Conclusion:</b> This study has demonstrated that all results of both mean values of total coliform and <i>E. coli</i> counts from groundwater of selected shallow wells and boreholes were beyond WHO standards, so water from Arabsiyo, Jaleelo, Dabaraqas, Dararweyne, and Darasalaam requires treatment before human consumption.展开更多
Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as oper...Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as operation pressure, cross-flow velocity, and slurry concentration, were examined and optimized. The shape and size of particles influenced the structure of the filter cake, leading to different permeation flux for different systems. The results demonstrated that washing using ceramic membranes is superior to the traditional plate-and-frame filtration and could be considered an advanced technique for ultra-fine powder preparation by wet-chemical method.展开更多
文摘<b>Background:</b> Shallow wells and boreholes are vital sources of potable water in Hargeisa. This water can be polluted by runoff, in particular during the rainy season, causing outbreaks of waterborne infections. <b>Objectives:</b> This research aimed at evaluating the microbial quality of shallow wells and boreholes water around Hargeisa, Somaliland. <b>Methods:</b> The total coliform and <i>Escherichia coli</i> count were done by using the membrane filtration method. Overall, 100 ml of each water sample was filtered via a 0.45 μm membrane filter, and then the filters were put on m-Endo agar plates that were incubated at 37°C for 24 to 48 hours. <b>Results:</b> The mean value of total coliform counts for the boreholes and shallow wells ranged from 1.288 × 10<sup>3</sup> to 8.8 × 10<sup>3</sup> CFU/100ml, while the mean value of total <i>E. coli</i> counts also ranged from 3.5 × 10<sup>2</sup> to 4.429 × 10<sup>3</sup> CFU/100ml. Results from this study have demonstrated that all water sources (Arabsiyo, Dararweyne, Darasalaam, Dabaraqas, and Jaleelo) don’t comply with the WHO guideline for drinking water. Results from the analysis of water samples of 28 wells demonstrated a significant correlation between total coliform and <i>E. coli</i> counts (P = 0.01). Therefore, this water is not fit for human consumption unless it is treated. <b>Conclusion:</b> This study has demonstrated that all results of both mean values of total coliform and <i>E. coli</i> counts from groundwater of selected shallow wells and boreholes were beyond WHO standards, so water from Arabsiyo, Jaleelo, Dabaraqas, Dararweyne, and Darasalaam requires treatment before human consumption.
基金financially supported by the Ministry of Science and Technology of China (Contract No. 2003CB615700)the Foundation of Science and Technology of the Educational Office of Anhui province, China (Contract No. 2005kj138)
文摘Washing using ceramic micro-filtration membranes was studied in the preparation of nano-sized TiO2 and A1203 powder precursors obtained by wet chemical methods. The key parameters for the washing process, such as operation pressure, cross-flow velocity, and slurry concentration, were examined and optimized. The shape and size of particles influenced the structure of the filter cake, leading to different permeation flux for different systems. The results demonstrated that washing using ceramic membranes is superior to the traditional plate-and-frame filtration and could be considered an advanced technique for ultra-fine powder preparation by wet-chemical method.
