THE PROBLEM: Cooling towers are a prime environment for the proliferation of micro-organisms due to the elevated temperatures and continual scrubbing of nutrients and dirt from the air. This continues to build as the tower operates and can cause serious problems both in the tower itself and in the system through which the cooling water circulates.

THE ANSWER: Control of micro-organism build-up in the tower is essential for efficient operation of the cooling loop. The need is for a biocide that is measurable, effective at all pH levels and demonstrates broad spectrum activity. One of the most efficient biocides for micro-organism control in cooling towers is chlorine dioxide. This is especially true now that cooling water treatment has been shifted into the alkaline pH range. In the alkaline range chlorine is not a particularly effective biocide because of the poor dissociation to HOCI.

The introduction of Chlorine Dioxide as a micro-biocide for recirculating cooling water systems has been proven to provide a very cost effective treatment for the prevention of algae and bacterial growths, even under very harsh environments.

Chlorine Dioxide will provide superior control of microbiological fouling in large cooling water systems, where traditional treatments have been unsuccessful, or cause other problems such as corrosion.

Chlorine Dioxide is a powerful oxidising agent and offers several technical benefits over other biocides in recycled cooling water applications.

Due to pollution problems associated with metal-based corrosion inhibitors most historically successful chemical programs based on actives such as chromate have been dropped. Modern water treatment corrosion and scale inhibitors are based on maintaining an alkaline environment; therefore the water pH is normally maintained between 8 and 9. At these pH levels, the effectiveness of chlorine and many non-oxidising biocides is greatly reduced, to the point where they are no longer cost effective treatments.

Some of the more important advantages of Chlorine Dioxide include; its biocidal properties are not effected by pH, ClO2 does not react with ammonia - nitrogen compounds, ClO2 does not require a free residual for microbiological control, and does not form chlorine substituted phenol compounds. Although historically Chlorine Dioxide has been an expensive oxidant to produce, its application in large recirculating cooling water systems is well justified, as it will often perform a task that other micro-biocide, such as chlorine, will not perform at any price.

With the introduction of the Single Vessel Process (SVP)from Eka WTS has the best available technology in chlorine dioxide generation. In the past, despite the obvious cost saving advantages over chlorite-based systems, small-scale sodium chlorate-based processes have not enjoyed widespread application. They were not able to achieve high chemical conversion efficiencies without excessive acid feed, undesirable by-products or the use of very sizable, costly systems.

Now, with the introduction of the patented Purate® process technology, all of this has changed.

The new process utilizes patented hydrogen peroxide chemistry that has been successfully operating in large production bleaching operations, and fulfils the demand for much lower levels of production.

·         RELIABLE - The SVP-Pure® generator system has proven reliable in long-term field applications. System design, materials of construction, and component selections are based on Akzo Nobel’s 30+ and WTS’s 25 plus years of experience in ClO2 process design and fabrication.

·         SAFE - As with all WTS installations, safety is a primary concern. The SVP-Pure ® design has undergone a rigorous hazard/safety analysis. A high level of safety is achieved with the application of emergency shutdown logic and our process safety design concept.

·         ELEMENTAL CHLORINE-FREE - In comparison to competitive technologies, the environmentally friendly Purate® chemistry requires no gaseous chlorine feed.

·         EASY TO OPERATE - An advanced on board PLC controls and monitors the system. Process information is routed to a touch-sensitive panel that is also used to configure the machine and provide local control. Remote capabilities of this machine include discrete start/stop as well as analogue rate adjustment. Flow pacing is also built in.

·         HIGHLY EFFICIENT –The SVP proprietary reaction vessel design optimizes mixing of feed chemicals yielding high conversion rates. System efficiencies of 95+% are consistently maintained.