UV requires a highly reflective surface, which is inert to UPW. While electro-polished stainless steel is highly reflective, the welds made to form these cylinders are subject to oxidation forming ferric oxide (rust) and therefore must be thoroughly passivated.
Ideally, all welds would have their bumpy pitted surfaces grounded and then properly passivated in nitric acid but this is not always the case. Stainless steel also contains chromium, nickel and molybdenum, which are all mobile ions when not thoroughly passivated and exposed to UPW. The mobile ions lead to integrated device failure.
U-PUR product combines the UV reactors with the mixed bed, in a 2-in-1 process, in order to remove the wetted surface of stainless steel. This represents a major advancement in UPW delivery and allows the system to deliver significantly higher water quality.
In recent years, hydrogen peroxide – a negative by-product of the UV – has become a topic of considerable interest. Ovivo by Ecolab includes an additional catalyst polishing step in the U‑PUR so that any peroxide generated is dissociated from the product stream. The standard 2-in-1 process can easily be upgraded to this 3-in-1 process at any time, without further modification of the system.
