Abstract
This study was aimed at introducing multistage filtration (MSF) (a combination of slow-sand filtration (SSF) and pretreatment
system - horizontal flow roughing filter (HRF)) as an alternative water treatment technology to the conventional one. A pilot- plant
study was undertaken to achieve this goal. Evaluating the MSF performance vs. the existing conventional system in removing
selected physical and chemical drinking water quality parameters together with the biological water quality improvement by the
MSF without chemical use was done. Evaluation of the effectiveness of the MSF system utilizing locally available material, i.e.
gravel, improved agricultural waste (charcoal maize cobs) and broken burnt bricks as pretreatment filter material was also done
The benchmark was the Kenya Bureau of Standards (KEBS) values for the selected parameters. Results showed that with proper
design specifications, MSF systems perform better than conventional systems under similar conditions of raw water quality and
environmental conditions. The tested locally available materials can also be effectively used as pretreatment media with each
allowing a filter run greater than 82 d and therefore could serve as alternatives where natural gravel is not readily available. With
special reference to the bacteriological quality improvement, the MSF greatly improved the bacteriological quality of the water
recording removal efficiencies of over 99% and 98% respectively for E. coli and total coliforms. Despite the observed performance,
MSF should be complemented with chlorination as a final buffer against water-borne diseases. However, in this case, the dosing
will be greatly reduced when compared to the conventional system.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001748 |
| Date | 03 July 2004 |
| Creators | Ochieng, GMM, Otieno, FAO, Ogada, TPM, Shitote, SM, Menzwa, DM |
| Publisher | Water SA |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | |
| Rights | Water SA |
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