potable water treatment
Water Treatment Services markets products for treatment of municipal and industrial potable water systems. These include corrosion inhibitors, scale inhibitors and polymers for use in clarification operations. All are accepted for use in potable water supplies at the concentrations indicated in the related product bulletins.
Clarification
For clarification of potable water supplies, Water Treatment Services offers a series of cationic, non-ionic and anionic polyelectrolytes in powder, emulsion and liquid forms. Strongly cationic organic polymers can be used as primary coagulants. Non-ionic, anionic and, in some cases, cationic organic polymers function as coagulant aids. These products range from non-ionic to strongly cationic or strongly anionic and are available in several physical forms. Technical assistance in the selection of the proper polymer for your specific application is available through your Water Treatment Services representative.
Corrosion & Scale Inhibitors
When added continuously to flowing potable water supply systems in low dosages, Water Treatment Services corrosion and scale inhibitors form a protective film on metal surfaces to minimize attack by oxygen and other corrosive elements. These products prevent lime scale deposition in high bicarbonate and lime softened waters and stabilize iron-bearing and/or manganese-bearing waters to prevent deposition of ferric and/or manganic hydroxides.
Disinfection
WTS offer a range of disinfection technologies based on chlorine dioxide, hydrogen peroxide and chlorine.
Chlorination
For chlorination, chlorine gas, sodium or calcium hypochlorite can be added to the water. The quantity required depends firstly on the chlorine demand of the water and the disinfection requirements. For potable water there must be a minimum residual concentration of 0.1 mg/l chlorine. A reaction period of at least 20 minutes is also normally required for effective disinfection in most applications. Water chemistry must also be considered, particularly pH. Experience shows the decreasing effectiveness of chlorine as the pH increases. This is to be expected because chlorine ionizes with water rapidly to form hypochlorous and hydrochloric acids. Hypochlorous acid, the primary biocide, dissociates as a function of pH, forming the hypochlorite ion. Hypochlorite is reported to be from 1/20 to 1/300 as effective at microbiological control as hypochlorous acid. Ammonia is often added to the water to improve the duration of the chloramine residual, particularly in long reticulation systems.
Chlorine Dioxide
Unlike chlorine, chlorine dioxide remains a true gas dissolved in solution. Chlorine dioxide is effective over a wide range of water chemistry and pH. The lack of any significant reaction of chlorine dioxide with water is partly responsible for it retaining its biocidal effectiveness over a wide pH range. This property makes it a logical choice for water systems where there is higher pH and organic contaminants that when chlorinated can lead to taste and odour issues. Chlorine dioxide is a means of disinfection that thanks to its multiple advantages replaces chlorine in more and more applications. Its effect is stronger and - above all - independent of the pH value of the water. Due to its chemical qualities it does not produce chlorine by-products. The longer half-life period helps create a better residual effect in the treated water. For drinking water a minimum residual concentration of 0.05 mg/l chlorine dioxide at a reaction time of at least 15 minutes should be observed. It is well established that chlorine dioxide - contrary to chlorine, degrades biofilm in pipelines and containers and thus renders growth of Legionella and other pathogens more controllable.
