Treatment

Ozone: a powerful alternative

Ozone is an incredibly powerful disinfectant – many times more effective than even chlorine, one of the most widely used chemical disinfectants in the water space.

Chlorine and other chemical disinfectants have long been popular for their price/performance ratio. However, ozone has proved to be a highly effective and useful alternative, treating numerous types of bacteria and other organisms.

On its own, ozone is a potent yet environmentally friendly disinfectant agent that outshines other choices. When using treatments that combine ozone’s immediate effects with long-term

disinfectants, the results and savings can be significant.

“Ozone doesn’t last long, and it leaves no chemical residual,” explains Brendan van Wyk, business development manager, Xylem. “If we were to disinfect a room with ozone, it would be hazardous to be in that environment during the procedure. But after about 20 minutes, it would be perfectly safe to re-enter the room, with little or no trace of any ozone being detected. This is because ozone (O 3 ) is very unstable and reverts back to oxygen (O 2 ).”

This view is backed by research, such as trials undertaken in 2014 by Campden BRI. It found that “ozone at

appropriate concentrations and contact times has the potential to be an effective environmental disinfectant.” The trial also established that, when used correctly, ozone caused no adverse contact effects afterwards.

Powerful disinfectant Ozone is brutal on organic material. Highly unstable, ozone attracts electrons from other compounds, oxidising them and drastically reducing their integrity. In the case of biological targets such as bacteria, ozone attacks their cellular walls, causing the cells to rupture and ensuring there is no chance for the organism to build up an immunity to it, unlike other disinfectants. Ozone is also very effective at oxidising certain minerals and can be used, for example, to remove manganese and iron from drinking water.

“Ozonated water is already used in places like abattoirs as wash water. This allows for maximum disinfection, but without a chemical residue that needs to be treated. It is easy to retrofit an ozone dosage system into an existing wash line. Clean technologies for rinsing and disinfection of milk bottles and soft drink bottles are already widely used,” says Van Wyk.

Ozone gas can further be used to thoroughly disinfect a room. Modern HVAC systems often use ozone to purify air passing through the system to prevent mould and odours.

Other examples of uses include cleaning animal enclosures and aquariums, rehabilitating smoke-damaged rooms, washing taxi ranks, and disinfecting laundry. Ozone-enriched water is a powerful disinfectant that leaves no chemical residual (as chlorine does) that could run into natural water systems through stormwater channels and disrupt natural biological action. Ozone gas breaks down quickly, being rendered into harmless oxygen that can enrich the local atmosphere and improve the chemical oxygen demand (COD) of wastewater.

Safe and cost-effective Ozone manufacture can be done quite easily and reliably, within a small footprint. With no moving parts and few maintenance requirements, the system can be operated remotely with no human intervention. Ozone only needs power and air for manufacture, and the units can be custom designed to suit the specific project specifications.

A modern ozone generator doesn’t require any chemical additives, therefore negating the need to stockpile chemicals, as well as the risks of handling dangerous materials. Ozone is also very cost-effective: its capital investment is soon recovered through water and chemical savings, as well as a reduction in effluent treatment costs. Recouping capital costs can take as little as two years on industrial systems such as cooling tower water treatment.

Van Wyk explains: “To give an example of how the costs work, let’s apply ozone to a water treatment plant. Normally, you’d apply large volumes of chlorine in the final stages of the treatment process. Much of this is first to disinfect the water, and the rest is to keep a residual for long-term disinfection.

“If we added an ozone generator to the treatment process, the water is disinfected without the use of chlorine, then a much smaller amount of chlorine is added at the end of the process to keep the water clean. Ozone does the heavy lifting of primary disinfection, without the generation of chlorinated by-products, while improving the taste and odour. It is much safer, and it requires smaller amounts of chemicals, so the costs of purchasing, storing and handling chemicals are reduced.”

Ozone technology offers different types of generators, from covering treatment plants to turning home pool water clean and bright. It is modular, environmentally friendly and a highly effective treatment product – without the need for the ongoing purchasing of chemicals and a workforce required for handling make-up and dosage requirements. The systems are self-contained and operate without human intervention, adds Van Wyk.

Ozone is nature’s own disinfectant: ruthlessly efficient but without leaving a calling card. Whether used to augment or replace other disinfection systems, ozone is a potent ally against infectious agents and a superior long-term disinfection and treatment investment.