Chlorine dioxide is an established and proven biocide with advantages over other biocides, including other oxidising biocides such as chlorine and bromine.
Chlorine dioxide is DWI (Drinking Water Inspectorate) approved for use in hot and cold water systems, is tested by BISRIA for Legionella Pneumophila efficacy and is accepted as part of the HSE ACoP L8.
Chlorine dioxide is normally dosed at a concentration between 0.3 and 0.5ppm for drinking water (DWI maximum is 0.5ppm as total oxidant). At this level there is virtually no detection as far as taste and odour are concerned. However, in other process applications the dose rate may be higher, particularly where the excess can be removed as part of the process.
Chlorine dioxide is stable in water and does not dissociate. This makes it much more suitable for use at higher pH levels than both chlorine and bromine. It does not react with impurities that may be present in the water to form THMs (tri-halo methanes).
Chlorine dioxide is normally produced in situ by the mixing of two chemical precursors - sodium chlorite and hydrochloric acid - in the correct concentrations and volumes to generate the gas in a safe and controlled manner.
Typical applications include drinking water, process water, pulp and paper bleaching.