Pilot testing of electrochemical oxidation technology for centrate ammonia reduction

A pilot scale ammonia oxidation system has been commissioned and its ability to remove ammonia from a centrate waste stream has been tested. The system, termed AmmEl by its manufacturer (Enpar Technologies), uses a stripping column and scrubbing tower to transfer ammonia from the waste stream to a brine solution that is pumped through an electrochemical reactor in which the ammonia is oxidized to nitrogen gas which is released to the atmosphere. Within the range of controlled settings tested, the system proved to be capable of removing up to 90 percent of the ammonia in the waste stream. The average cost is {dollar}7.17/m3 centrate for 76 percent ammonia removal from centrate having a mean initial ammonia concentration of 853 mg/L. Caustic soda accounted for the major portion of the treatment cost; this was followed by the energy costs. This operating cost may be reduced by 30% if centrate is treated in summer (20 to 25°C).