Dechlorinator

Abstract: A chlorine dioxide bleaching process is disclosed that improves the efficiency of bleaching paper, reduces the consumption of chemicals, water and heat, and minimizes waste disposal problems. The essential feature of the invention is a two-stage system for generating chlorine dioxide in which partially spent chemicals discharged from the primary generation stage are more completely reacted under controlled conditions in a dechlorination stage. Since chlorine dioxide solution from the dechlorinator is somewhat contaminated, it is separately collected for use in the early pulp chlorination stages while the purer chlorine dioxide from the primary generator is reserved for use in the latter stages of pulp bleaching. The chloride content and corrosiveness of the spent reagents are minimized by this process which not only provides for economical utilization of the chemicals but also makes it feasible to add the underflow from the dechlorinator to the black liquor recovery system and so increase the recovery of sulfides. Waste disposal problems and the consumption of water are minimized by recycling free acid from the dechlorinator to the generator and by utilizing the filtrate from the last stages of pulp washing as the absorption media in the chlorine dioxide absorption towers.

Abstract: The present invention is a solution for detoxifying contaminants, such as ammonia, chlorine and chloramine, in aquatic systems. The solution includes a composition of an amine-based ammonia detoxifying compound, in an amount effective to detoxify substantially all of the ammonia, and a dechlorinator. An aqueous solution of the amine-based compound is acidified to adjust the pH to form a stable, non-toxic solution suitable for aquatic life. In addition, methods for preparing the detoxifying solution are disclosed.

Abstract: : Aquatic biomonitors can provide continuous, real-time monitoring for toxicity in source water supplies, but they cannot be used to directly monitor chlorinated drinking waters because of aquatic organism sensitivity to residual chlorine. The threshold for a toxicity alarm by a biomonitor using bluegills (Lepomis macrochirus) was between 0.015 and 0.066 mg/L total residual chlorine (TRC). A portable dechlorinator that injected 6 mg/L sodium bisulfite into water containing 1.5 to 2.0 mg/L TRC was effective in removing TRC-related toxicity during a nine month evaluation at a water treatment plant. Three biomonitor alarms that occurred were not caused by dechlorinator malfunctions. In one-hour laboratory exposures to sodium bisulfite alone, the biomonitor did not respond until concentrations exceeded 48 mg/L. This study demonstrated the feasibility of using a biomonitor in conjunction with a portable dechlorinator for continuous monitoring of chlorinated drinking waters. Future studies should evaluate dechlorinator suitability in waters with total organic carbon levels exceeding 2 mg/L or that have been disinfected with chloramines.

Abstract: A method for detoxifying ammonia in an ammonia-containing aquatic system comprises adding to the system a novel composition comprising an amine-based ammonia detoxifying solution in an amount effective to detoxify substantially all of the ammonia, where the solution is non-toxic and has a pH suitable for aquatic life. Further, a method for detoxifying contaminants selected from the group consisting of ammonia, chlorine and chloramine from a contaminated aquatic system comprises adding to the system a novel composition contaminant according to the present detoxifying solution in an amount effective to detoxify the contaminants, the solution comprising an amine-based ammonia detoxifying compound and a dechlorinator, where the solution is stable, non-toxic and has a pH suitable for aquatic life. In addition, methods for preparing the ammonia detoxifying and contaminant detoxifying compositions and the compositions produced thereby are disclosed.