Alternative water sources for urban consumers – A novel technology for the City of Cape Town urban resident
South Africa is classified as being the 30th driest country in the world and is regarded as a water scarce country. However, for the urban residents of the City of Cape Town, the ability to reduce their municipal water consumption through initiatives, other than simply using less water, is limited. Hence, there is a need for affordable, simple and compact technical solutions which allow urban populations residing in high density developments to make use of alternative sources of water, specifically greywater, to reduce their municipal water demand. Existing commercial technologies were considered, together with the socio-economic and technical constraints of an illustrative middle-income urban household in the City of Cape Town (CoCT). It was found that each commercial technology considered satisfied some, but not all, constraints characteristic of the household. For instance, the treatment device may produce treated water of a high quality. However, it may not be financially feasible for the consumer. Of the commercial technologies considered, there is no single commercial technology which can offer a complete solution within the socio-economic and technical constraints of the household. For this reason, the opportunity exists to produce an innovative technical solution. The proposed greywater treatment device consists of four cylindrical chambers in a vertical arrangement. Raw greywater enters the top chamber and treated greywater is extracted from the bottom chamber forming the base. The treatment processes undergone as the greywater flows through the treatment device include, in the following order, pre-filtration, biological treatment (Activated Sludge), clarification, filtration and disinfection. The process is driven by a combination of gravity and electrical energy. The proposed design is constructed using readily available materials and components. It is modular in its construction, allowing for easy maintenance, assembly and an increase in design flexibility. Evaluating the design against the same evaluation criteria stipulated for the existing commercial technologies showed that the proposed design may be an appropriate solution for the illustrative middle-income household within the City of Cape Town and is a novel technical solution.
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