Erratic rainfall, urbanisation, ageing infrastructure and a combination of a shortage of funds and of technical skills in municipalities are contributing to a gradual deterioration in the country’s drinking water quality.
While it is still safe to drink tap water in larger cities, it is becoming riskier in towns
Drinking water is sourced from rivers and streams, into which poorly managed waste-water treatment plants — particularly in rural areas — are emitting millions of litres a day of partially treated or untreated water. With rainfall patterns changing as a result of global warming, there is less fresh water available to dilute contaminants.
According to the Department of Water and Sanitation’s latest Green Drop report, by this year most of SA’s waste-water treatment plants were in the high-risk category, and one-quarter required urgent intervention.
Prof Anthony Turton of the Centre for Environmental Management at the University of the Free State says SA produces 5-billion litres of sewage a day, of which only 20% is treated to a standard safe to discharge into water sources.
But water constraints present both risks and opportunities, Turton says.
Cape Town-based San Aqua HCA, which designed and patented a solution called HydroChemical Activation (HCA), is one that has seen an opportunity in this predicament.
It has run informal tests with 1.8Ml-, 0.5Ml-and 0.25Ml a day municipal water treatment plants, which co-founder Pamela Alborough says surpasses expectations. HCA is an improvement on an existing process called electrochemical activation, in which an electrical charge is applied to water to sterilise it. HCA, which uses platinum group metals and other catalysts, eliminates the need for separate anode and cathode cells and puts a higher effective current through the water.
The reactor cells create a high frequency magnetic field that disrupts the molecules, generating peroxide and ozone.
Peroxide and ozone sanitise the water. The process also coagulates inorganic material, that can easily be filtered out and sent to a landfill site for disposal. The HCA system can incorporate sensors feeding information on the quality of the water and system performance to a central computer.
Alborough says HCA is designed to be an add-on to an existing municipal waste-water treatment plant of between 0.1Ml and 50Ml a day. It does not replace the existing infrastructure at a municipal plant, but can double capacity as it enables contaminants to be removed faster and more effectively.
HCA needs no special skills to operate. It needs a power source, but uses only the equivalent of eight light bulbs at a flow rate of 1Ml a day.
To treat 1Ml, the equipment consists of an electronic power supply and two minireactor units, about 16cm in diameter. The reactors can be doubled in size and quantity as volumes increase, making the system scaleable.
The capital cost of a full municipal waste water plant is about R8m per megalitre of capacity. The HCA plant can cut this spend to about R4m-R5m/Ml. It also reduces operating costs because fewer chemicals are needed.
But municipalities are conservative decision-makers, so San Aqua is marketing the solution to businesses and high-density residential estates, anticipating that once municipal managers see it working in the private sector, they will be prepared to adopt it.
Department of Water Affairs and Sanitation spokesman Sputnik Ratau says that new technologies are of interest but there is no "one-size-fits-all" solution. Each municipality will decide what is best. At least five municipal treatment works are using new or alternative treatment technologies.
San Aqua is a semifinalist in 2016’s Global Cleantech Innovation Programme, which helps entrepreneurs to commercialise new technology that takes care of energy and environmental challenges.