Dechlorination of wastewater effluent is common practice in many wastewater treatment facilities throughout the U.S. Strongly reducing sulphur compounds are used to eliminate chlorine residuals that might prove toxic to fish in the receiving stream. Because residual chlorine discharge limits are often very close to zero, monitoring residual values to comply with regulations has become very difficult, and controlling residuals at values between zero and 10 or 20 parts-per-billion is often not achievable.
To meet stringent discharge limits, the sulphiteor bisulphte used for dechlorination is added in slight excess, providing a small sulphiteresidual to insure complete dechlorination.
ATI’s Model Q46S/66 sulphite monitor provides operators with a reliable tool for maintaining a small sulfite residual while reducing excess chemical consumption due to overfeed.