Business: UV and Ozonation Ideal for Treating Wastewater
Recent Gauteng Business News
While sometimes perceived as new technology, the principles of both UV and ozone have been known for more than 100 years. “These environmentally friendly technologies, used in Wedeco products from ITT Water and Wastewater, offer the much sought after answer to the issues of water pollution and shortages,” Richard White, business unit manager public utilities ITT Water and Wastewater, says. “In addition to dispensing with chemicals, they also offer low initial capital costs and reduced operational expenses.”
UV is considered hugely desirable as a purely photochemical process that does not change the taste or composition of water. It can replace chlorine as the main disinfectant. It is particularly effective, for instance, in destroying cryptosporidium, a parasite that is sometimes found in surface water and has caused major health outbreaks.
White explains that treatment with UV lamps involves penetration of the cell walls of an organism, causing disruption of the cell’s genetic material to prevent reproduction. “The Wedeco UV lamps and reactors effectively destroy bacteria and viruses within a short time frame and can be easily used with minimal fuss.”
Wedeco also produces an ozonation system that has been very successfully used for wastewater oxidation. Other applications include drinking water treatment, pulp and paper bleaching, industrial wastewater treatment, and treatment of circulation loops in cooling towers of power plants.
“Traditional physical/chemical methods of wastewater treatment such as flocculation, filtration and chlorination are insufficient to ensure the quality and safety of drinking water,” White says. “The biggest advantage when it is compared to the other methods is that ozone directly destroys contaminants and pollutants, micropollutants, colours, odours and micro-organisms without any harmful by-products or residuals.
“Because ozone is generated on demand, there is no need to store dangerous chemicals and DBP generation is dramatically reduced,” White says. While some people may argue for the continued use of chlorine in the treatment of wastewater, it is clear from verified laboratory tests that one needs to use a higher dosage rate or a much longer reaction time in order to achieve complete disinfection. “In addition, high chlorine dosages include the risk of generating high levels of chlorinated by-products while, conversely, too low a dosage of chlorine could cultivate chlorine resistance.”
While the water quality is of the utmost importance, the old adage ‘you can bring a horse to water, but you cannot make him drink’ would apply with the addition of ‘especially if the water tastes bad or has an undesirable odour’.
Organic compounds that occur during the anaerobic decomposition in ground and surface water under high oxygen deficiency usually impart an unpleasant taste and odour. Ozone oxidises such compounds in the aqueous phase and destroys the unwanted taste and odour.
Algae have a tendency to grow on surface water and impart an offensive taste and odour to the water, originating from plants with this problem. “Ozonation will oxidise and simultaneously destroy the algae to remove the earthy odour and taste from the finished water,” White says.
Naturally occurring organic material such as humic, fulvic and tannic acids cause discolouration of surface waters and because ozone is known for its ability to react in a rapid and specific way with double bonds, the process results in the water becoming clear and colourless.
“A combination of both the Wedeco Effizon® HP range of ozone generators with the Wedeco UV disinfection system is the perfect alternative to other alternative methods of producing clear, clean drinkable water that is as close to its pure original state as possible,” White concludes.
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