TREATMENT OF POLLUTED WATER USING NATURAL ROCK MATERIAL AT THE HOUSEHOLD LEVEL

Abstract

BACKGROUND: In rural and semi-urban communities of developing countries, including Ethiopia, adequate water treatment procedures are almost non-existent, mainly for economic reasons as well as settlement characteristics of the people. Hence, a technology that does not demand much financial resource at household level is required. The aim of this study was to test the filtering capacity of natural rock material obtained in the rift valley of Ethiopia

METHODS: The rock material "Pumice" was collected from Metehara and Awash-7 Kilo areas, the rift valley of Ethiopia and then designed into rock vessels which were 2cm, den and 6cm, cylindrical and hemispherical shapes at the top and bottom, respectively. Three experimental cycles were under taken, Polluted water samples that had initial average concentration of 497 Most Probable Number (MPN) per 100mL of faecal coliforms, 93. 2 Formazine Turbidity Unit (FTU) of turbidity, 83.3 True Color Unit (TCU) of color, 1.405 mg/L of fluoride, 0.63 mg/L of iron, 0.028 mg/L of manganese and a pll of 6,74 ar a temperature of 20.5°C were passed through the rock vessels.

RESULTS: There was a very good reduction of contaminants in which faecal coliforms became 96.4%, 97.6% and 98.4%; turbidity 96,5%, 96,7% and 96.9%; color 88%, 89.2% and 92.8%; temperature 5.9%, 6.15% and 6.3%; fluoride 22%, 38.6% and 67.5%; Iron 79.4%, 87.3% and 88.9%; manganese 67.9%, 89.3% and 92.9%; but, the mean averages for the hydrogen ion concentration (P value) increased gradually to 6.53%, 8.2% and 6.7% in 2cm, 4cm and 6cm rock filters, respectively. The study has revealed that, as the filter run increased, the efficiency to eliminate the contaminants was positively significant (p>0.05). It was also observed that there is a declining trend in filtration rate as the frequency of the filter run increased.

CONCLUSION: Natural rock filter has the capacity to filter impurities from contaminated water. It is a relatively simple technology for household water treatment Further studies also need to be done on other removal mechanism (adsorption capacity of the rock), characterization of the rock and the application of this natural rock as a conventional water treatment media, which are not included in this study.