Abstract:
The Decentralised Wastewater Treatment System (DEWATS) can provide a potential sanitation solution to residents living in
informal settlements with the effluent produced being used on agricultural land. This paper reports on a first step to assess the
technical viability of this concept. To do so a pilot DEWATS plant was connected to 83 houses in the eThekwini Municipality.
An experiment was conducted in a randomised complete block design with 2 treatments (DEWATS effluent irrigation and tap
water irrigation + fertiliser) and 3 blocks. Banana and taro crops were irrigated using an automated drip irrigation system.
Data on the weather, crop growth, nitrogen and phosphorus uptake and soil chemical properties were collected. Irrigation with
DEWATS effluent was comparable to tap water + fertiliser especially for banana growth and biomass production. Banana and
taro required 3 514 mm of irrigation effluent. About 0.0117 ha·household−1 (23.3 m2·person−1) was found to be an adequate area
for effluent reuse. Wet-weather storage requirements were calculated to be about 9.2 m3·household−1. DEWATS effluent, after
passing through a horizontal flow wetland, was unable to meet banana and taro nitrogen and phosphorus requirements. Nutrient
monitoring is required when using anaerobic filter effluent from a DEWATS for irrigating banana and taro.
Description:
The research was carried out under Project No. K5/2220
(Integrating Agriculture in Designing On-Site, Low Cost Sanitation
Technologies in Social Housing Schemes) of the Water Research
Commission of South Africa. Further acknowledgements go to
Bremen Overseas Research and Development Association (BORDA)
and the eThekwini Water and Sanitation (EWS) Department.
