Assessment of Physicochemical and Bacteriological Quality of Drinking Water Supply from Different Boreholes of Addis Ababa
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Date
2018-02-02
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Addis Ababa University
Abstract
Assessment of physicochemical and bacteriological quality of drinking water is important to protect public health. Little is known about the quality of drinking water in Addis Ababa. Therefore, this study was aimed to assess the physicochemical and bacteriological quality of drinking water in different sites of Addis Ababa and determine whether the drinking water quality meet the national standards and WHO criteria guideline values for drinking water quality standards. A total of 180 water samples were collected and analyzed in triplicate sampling from selected 20 boreholes. The mean physicochemical and bacteriological quality of each method were calculated and compared with the set standards of WHO and National standards.
The mean physical parameters of the boreholes were ranging from pH (6.6±.5) Ararat to(7.7±.7) Yeka borehole in Northern Addis Ababa; temperature 21.8±.6°C Alemgena Southern Addis Ababa to 26.4±1.02°C BH6 in Central Addis Ababa; TDS 230±3.5mg/l Alemgena to 308±12.2mg/l Mekanisa197 borehole in Southern Addis Ababa; EC 458.7±5.6µS/cm Alemgena in Southern Addis Ababa to 639.3±31.7µS/cm BH24 in central Addis Ababa; turbidity 0±0 to 0.13±0.08NTU. And the physical parameters of the sites were ranging from pH 7.1±.3 in Central and Southern Addis Ababa to 7.1±.8 in Norther Addis Ababa; temperature 23.8±.8°C in Southetn Addis Ababa to 24.8±.8°C in Northern Addis Ababa; TDS 247.1±.15mg/l in Southern Addis Ababa to 271.4±9.1mg/l in Northern Addis Ababa; EC 534.8±29.8µS/cm Southern Addis Ababa to 543±9.1µS/cm in Northern Addis Ababa and turbidity 0.01±.01NTU in Northern and Southern Addis Ababa to 0.02±.01NTU in Central Addis Ababa.
The mean chemical parameters recorded of the boreholes were ranging for nitrate 3.5±.7 mg/l Selam to 33.9±1.8mg/l Ankorcha2 boreholes in Northern Addis Ababa; DO 4±1.2mg/l Mekanisa296 borehole in Southern Addis Ababa to 8.9±.2mg/l BH24 in Central Addis Ababa and BOD 0.21±.11 mg/l Selam borehole in Northern Addis Ababa to 3.±.11mg/l BH14 in Central Addis Ababa; which were above the WHO limit. Moreover the mean Fluoride values ranges from 0.55±.03mg/l Ararat borehole in Northen Addis Ababa to 0.98±.01mg/l BH19 in Central Addis Ababa all boreholes below WHO limit for domestic water use. Whereas, the mean chemical parameters of the sites were ranging from nitrate 10±.8mg/l in Southern to 25.6±1.8mg/l in Central Addis Ababa; DO 6.4±.6mg/l in Southern Addis Ababa to 7.3±.5mg/l in Northern Addis Ababa and BOD 0.98±.32mg/l in Central Addis Ababa and 1.2±.33mg/l in Southern Addis Ababa. In addition the mean average fluoride 0.67±.04mg/l in Northern Addis Ababa to 0.69±.06mg/l in Southern Addis Ababa.
The mean bacteriological counts of the boreholes were ranging from 26±1.5CUF/100ml to 217.3±5.8CFU/100ml; 20±7.6CFU/100ml to 75±2.1CFU/100ml, and 0±.0CFU/100ml to 23±2.9 CFU/100ml for TC, FC and FS respectively. The mean of the sites were range from 73.6±34.6 CFU/100ml in central Addis Ababa to 39±8.2CFU/100ml in southern Addis Ababa for TC; 28±7.2CFU/100ml in Southern Addis Ababa to 46±6.6CFU/100ml in Northern Addis Ababa for FC and 8±1.1CFU/100ml in Southern Addis Ababa to 13±1.9CFU/100ml in Northen Addis Ababa for FS. Inwhich both were above the permissible limit of WHO and national standards except Alemgena borehole in Southern Addis Ababa (FS=0±.0CFU/100ml) which comply with the WHO criteria and national standards. The bacteriological quality and temperature of most of the boreholes and all of the sites did not meet ES and WHO standards.
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Keywords
Addis Ababa, Boreholes, Fecal Coliforms, Fecal Streptococcus and Physicochemical Water Quality.