Chlorine dioxide sodium chlorite feed

It is important to follow equipment manufacturer s instructions to generate chlorine dioxide efficiently. Adjustments to chlorine and sodium chlorite feed may be necessary to optimize production and minimize forming unwanted by-products (chlorate, chlorite, or excess chlorine). The high-yield production of chlorine dioxide depends on the relationship of chlorine to sodium chlorite, pH, and other factors. Precise and accurate control of all variables is necessary to produce the highest-purity product and to minimize undesirable byproducts. 

The feed rate of chlorine and sodium chlorite is linked to the feed of chlorine dioxide because these are the primary chemicals used in most generation systems. The most common sources of chlorine are compressed gas and liquid sodium hypochlorite (12 percent trade is a common solution strength). Sodium chlorite is commonly used as a solid (about 65 percent sodium chlorite) and as a 25 percent strength solution. 

Chlorine dioxide is produced on-site, as needed, for the application. At least two chemicals are combined to form chlorine dioxide. While a few proprietary chlorine dioxide feed systems exist, most systems used in water treatment plants combine chlorine gas (some use liquid sodium hypochlorite) with sodium chlorite (either solid or liquid). A chlorine dioxide solution is then fed at the point of application. Although chlorine dioxide feed systems are often a hybrid of gas and liquid (or solid), this discussion is included in the gas feed section of this book because the chlorine gas is commonly the controlling factor in this system. 

This relationship can he further expanded hy substituting the equation for chlorine dioxide feed shown in calculators c4-12 and c4-13. Thus, we have the basic relationship (c4-14) that is useful in calculating the sodium chlorite of any concentration needed to produce a given amount of chlorine dioxide. Remember, these relationships are drawn from the chemical equations, thus 100 percent efficiency is assumed. Lower efficiency therefore results in amounts that differ from these calculated values. However, the calculated values are useful to estimate chemical use, and these can be used to evaluate generator efficiency (see A Generator Purity Calculation, p. 53). 

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