Dechlorination of Water for Fish Culture: Comparison of the Activated Carbon, Sulfite Reduction, and Photochemical Methods

Abstract

Activated carbon, ultraviolet radiation, and sodium sulfite were evaluated as dechlorinating agents. Activated carbon tested in a variety of commercial dechlorinators was not 100% effective in chlorine removal. The residual concentration remaining after carbon dechlorination varied from 5 to 70 μg/L depending on how long the carbon had been in service and on the flow rate through the carbon bed. Ultraviolet radiation effectively removed residual chlorine from water but compared with the other two methods was considerably more expensive. Sodium sulfite was 100% effective but required a fail-safe injection system. A system combining the reliability of carbon dechlorination with the effectiveness of sulfite reduction was developed and shown to be safe, effective, and reliable. Key words: water quality, toxic levels, system design, operating costs, new methods