Evaluation Of Household Bio-sand Filters For Pathogen And Inorganic Substances Removal Efficiency In Adaa Woreda Oromia Region

Ethiopia 60-80 % of the population suffers from water-borne and water-related diseases. Thisrnis partly due to the lack of access to the safe centralized water distribution system in the country.rnIn response to this crisis, decentralized point-of-use systems, such as Bio-Sand Filter, hasrnemerged as a feasible option for improving water quality at the household level. This thesisrnevaluates the efficiency of Bio-Sand Filters and source water quality through physico-chemicalrnand biological water quality analysis in selected villages of Ada’a woreda, Oromia Regional State.rnThe study was conducted from December, 2007 to February, 2008 three times in one monthrninterval. A total of 612 triplicate water samples were collected and analyzed from four mainrnsource water and 100 randomly selected households. The household Filters were evaluatedrnbased on reduction capacity of turbidity, Iron, manganese, nitrate, phosphate, TC and FC fromrnthe raw water samples using standard methods. Moreover, flow rate of the filters and change inrnpH, temperature, TDS, EC, DO level of the raw and filtered water were also studied to evaluaternthe filter performance. In Dire Bote Village, the filters reduced TC counts of the raw waterrnsamples from 1323±134 to 109±27 cfu/100 ml, FC counts from 288±42 to 16±4 cfu/100 ml.rnSimilarly, the filters reduced turbidity from 196.1±66.2 to 17.4±15.5 NTU, Iron from 1.0±0.3 torn0.3±0.2 mg/l and manganese from 0.5±0.2 to 0.1±0.1 mg/l, phosphate from 0.7±0.4 to 0.6±0.4rnmg/l and nitrate from 8.0±4.6 to 6.4±4.6 mg/l. In general, the efficiency of the filters was found tornbe 91.8% for TC, 94.3 % for FC, 95% for turbidity, 70% for Iron, 80% for manganese, 20% forrnnitrate and 14.3 % for phosphate with average flow rate of 6.5±2.2 l/h. Likewise, in Chirecharnvillage, the filters with filtration rate of 4.4±3.9 l/h reduced TC counts of the raw water fromrn2710±856 to 136±78 cfu/100 ml, FC counts from 380±69 to 3±1 cfu/100 ml. Moreover, the filtersrnreduced turbidity from 499±179.4 to 8.4±7.2 NTU, both Iron and manganese from 0.7±0.4 torn0.1±0.1 mg/l, phosphate from 0.9±0.8 to 0.7±0.5 mg/l and nitrate from 7.2±5.5 mg/l to 5.8±4.8rnmg/l. The efficiency of the filters was found to be 95% for TC, 99.3 % for FC, 98.3% for turbidity,rn85.7% for both Iron and manganese, 19.4% for nitrate and 22.2% for phosphate. In both villages,rnthe average flow rate of the filters was found to be below the acceptable limit of 20-40 l/h mainlyrndue to high turbidity of the raw water. It was also observed that high turbidity of the source water,rnreduction of the sand bed of the filters, lack of monitoring and supervision by concerned bodiesrnare said to be the main causes for low performance of few of the filters. Planting trees around thernpond to reduce the silt load carried by runoff to the pond water, integration between therncommunity and the Woreda Water Desk, strengthen the water committee of the village, andrnintroduction of monitoring and supervision mechanisms may also improve quality of the water tornthe community. Generally, this study showed that the BSFs installed in the study villages havernimproved the water quality parameters of the source water. After filtration, all water samples metrnthe WHO and the national water quality guideline values except microbial and turbidity contentsrnof the water.

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