Applicable Of CDD 5000 In Potable Water Treatment.
Criteria for selection of a biocide depend on the following aspects.
- Regulatory guidelines.
- CxT ( Concentration x Time).
- Spectrum of biocide.
- Formation in Disinfection byproducts’.
- Safety & operational ease.
Chlorine dioxide is a versatile broad spectrum disinfectant that can also be used as a primary disinfectant in potable water, as it reduces or controls bacteria, viruses, cysts and algae(pseudomonas, e.coli, Cholera,cryptosporidium,Giardia, etc…).while being effective over wide temperature & pH ranges. Using chlorine dioxide will help optimize overall treatment efficiencies, including improved coagulation, reduced turbidities, improved particulate removals, increased CT values and lower THMs and HAAs levels.
It has superior disinfection capabilities over elemental chlorine and, through its selective chemistry, it reacts quickly to oxidize and reduce the organic load in the water. Chlorine dioxide is not a chlorinating agent and can be used as a primary disinfectant, or as a raw water oxidant, for THM and HAA precursor reduction in potable water treatment systems.
Chlorine dioxide is an interesting alternative to Chlorine because of the completely different relationship involved between action and reaction. Chlorine dioxide does not produce organic, chlorine compounds with those contaminants most frequently found in water, e.g. Chloro phenols or halogenated Hydrocarbons (for example Halo forms such as Chloroform which is considered carcinogenic).The compounds formed from the reaction of Chlorine dioxide with organic water contaminants are therefore largely negligible in terms of sensory or toxicity considerations. This makes Chlorine dioxide an ideal disinfectant for the treatment of drinking water and process water or for circuit water systems.
Traditional chlorine treatment limitations include lack of adequate retention time, elevated pH system water and achieving CT compliance, which results in elevated halogenated disinfection byproduct problems. Chlorine dioxide has a lower CT value than chlorine resulting in less detention time, is not pH sensitive at typical water production and is not a halogen so it won’t chlorinate organics to form THMs or HAAs.
Many potable water plants have experienced unpleasant tastes and odors in finished waters. Descriptions range from medicinal, musty and earthy to metallic and rotten egg. These odors are caused by substances generally produced in raw waters by various algae or bacterial micro-organisms. Chlorine dioxide is effective in oxidizing low-threshold-odor compounds like Geosmin and MIB at typical treatment dosages. It also has the advantage of not chlorinating organics.
Chlorine dioxide, when used as a primary disinfectant in potable water treatment,is a powerful oxidant with CT values second only to ozone in biocidal efficacy, but without the high capital expenditures and the ozonation byproducts. In addition, chlorine dioxide does not have the solids loading problem and the lengthy detention times associated with potassium permanganate. Using chlorine dioxide does not result in the formation of chlorinated or brominated disinfection byproducts like THMs or HAAs. A reduction byproduct of chlorine dioxide is chlorite ion.
pH Independence. The main advantage of using Chlorine Dioxide for disinfection is the pH independence of the reaction. Unlike chlorine, Chlorine Dioxide ClO2 will inactivate pathogenic micro-organisms at the same rate between pH 5 and 9. This makes it ideal for disinfection of potable water and process water where the pH is up around 8.0. Chlorine hydrolyzes to hypochlorite ion significantly around pH 8.0 which renders it quite ineffective for disinfection.
Biofilm removal – ClO2 is the only molecule which can maintain a residue and also do a task of biofilm removal in potable water system and pipelines carrying the water.
Application of CDD 5000 in potable water –
Chlorine dioxide’s broad spectrum capabilities enable it to be used in a variety of potable water applications
- Iron & Manganese Oxidation
- Taste & Odor Control
- Trihalomethane (THMs) & Haloacetic Acids (HAAs) Control
- Color Removal & Algae Control
- Cryptosporidium Inactivation
- Nitrification Control
- Zebra Mussel Control