Abstract
A survey involving 181 water treatment plants across 7 provinces of South Africa: Mpumalanga, Limpopo, North West,
Free State, KwaZulu-Natal, Eastern Cape and Western Cape was undertaken to identify the challenges facing small water
treatment plants (SWTPs) in South Africa . Information gathered included ownership and design capacity of the plants,
water sources, and various methods of disinfection, equipment currently employed and performance of the treatment plants.
In general, the majority (over 80%) of the SWTPs surveyed in the designated provinces were owned by the district municipalities.
The designed capacities of these plants varied between 1 and 60 Mℓ/d; the smallest capacity was 100 m3/d and the
largest 120 Mℓ/d. The small water treatment plants abstracted their raw water from either surface or groundwater or a combination
of both water sources with greater preponderance for surface water sources (over 86%). Water treatment practices
were noted to be the conventional types mainly coagulation, flocculation, sedimentation, filtration and disinfection. Two
types of coagulants namely polyelectrolyte (66%) and alum (18%) were commonly used by the water treatment plants across
the provinces studied. Rapid gravity filtration, pressure filter and slow sand filtration systems accounted for 60%, 23% and
9% of the filtration systems across the provinces, respectively. The predominant types of disinfectants employed were chlorine
gas (69%) followed by sodium (15%) and calcium (14%) hypochlorite. Over 50% of the various SWTPs did not comply
with the SANS 241 Class I (< 1 NTU) and Class II (1 to 5 NTU) recommended turbidity values. The recommended target
range of 0.3 to 0.6 mg/ℓ free chlorine residual concentrations at the point of use was not always met by 40% of the plants.
Seventy percent of the SWTPs complied with the SANS 241 criteria of microbiological safety of drinking water vis-à-vis
total and faecal coliforms. Operational problems affecting the efficiency of small water treatment plants included: inability
to appropriately determine the flow rate, chemical dosage and turbidity, lack of chlorine residual at the point of use and lack
of water quality monitoring. To produce safe drinking water, appropriate operational practices must be implemented in all
small water treatment plants.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1001759 |
| Date | 12 March 2008 |
| Creators | Momba, MNB, Obi, CL, Thompson, P |
| 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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