Large scale desalination is Saudi Arabia’s trademark in the world of water. Thirty massive plants producing millions of cubic meters a day in total are the focus of business attention.
However, their output does not reach all corners of the Kingdom and local boreholes and wells, often brackish, supplement supplies tinkered in.
Instead of running expensive pipelines to remote communities, there is a viable alternative. The Republic of South Africa shares in its remoter areas, similar problems of small communities needing supplies of potable water with only brackish groundwater available. Rather than turn to capital-intensive desalination plants, ingenuity and the application of simple but reliable technology produces highly effective results.
For decades the only sources of water for the small rural community of Kerkplaas, in the arid Klein Karoo, in South Africa, was one borehole delivering undrinkable brackish water. A municipal water tanker arrived at the far-flung settlement only sporadically. Often the 40 permanent residents and primary school with 25 pupils, some who traveled kilometers to attend, had to go without water.
A high-tech research project funded by South Africa’s Water Research Commission, the country’s primary funding agent for water research projects, has now ensured a permanent supply of drinking water.
Working in partnership with the Department of Chemistry at the University of Stellenbosch and the Chemical Engineering Department of the Cape Town Technikon, private company McCracken Solar Stills developed a technology for the Kerkplaas community using locally-available, cost-effective material. The technology harnesses the energy of the sun, the same much underutilized and free source of energy that blesses the Kingdom, to treat water from the local borehole.
Project Manager Ian Goldie, said that a total of 15 solar stills were constructed at Kerkplaas. Each solar still consists of a flat pan (or basin) covered by a transparent cover. The saline water from the borehole is fed into the basin, where partial evaporation takes place through solar heating. Direct and scattered radiation from the sun heats water in the closed container where it evaporates. Impurities, including dissolved minerals, are not evaporated and are left behind as solid deposits.
Condensation takes place against the cover, and the distilled droplets run off into a collection container. This still does not require an energy source other than sunshine.
As the distilled water contains hardly any dissolved solids (typically less than 10 parts per million), it is blended with source water to achieve the required water quality and is thus more economical. This water is then stored and used by the community.
In Kerkplaas, where solar radiation levels are extremely high in summer (September to March), the 15 stills together produce up to 350 liters of water a day, with total dissolved solids (TDS) not exceeding 1000 mg/l (compared with the borehole TDS count of 2000 mg/l).
The community has actively participated in the project from the start, even identifying the project site. Maintenance and operator input is little, with routine plant monitoring and water sampling undertaken by trained members of the community.
The Kannaland Municipality has recently taken ownership of the plant on behalf of the Kerkplaas community, and another solar still plant has been erected at the nearby Algerynskraal community. This plant can deliver up to 400l of potable water a day.
Keen interest has been shown in the technology by organizations such as the Development Bank of Southern Africa.
As a cost efficient method of providing drinking water, these simple solar stills are unbeatable. However, perhaps more important in the long term is the educational element in community operation of the solar stills.
As community members are involved in the production of their own life-giving water, understanding of the science of production and husbandry of water develops in tandem. When eventually piped water reaches the community, conservation and an understanding of water use will be embedded in the local culture.
While the main focus, especially during the drive to privatize and turn water production and distribution into a profit center for investors, perhaps a parallel plan might be to introduce simple effective and above all, inexpensive technology into remote areas that could really make use of it; and now.
