Optimized energy consumption in electrochemical-based regeneration of RAS water

Abstract

The rapid expansion of the aquaculture industry and seawater recirculating aquaculture systems (SW-RAS) parallel to the human growth require more efficient water consumption while preserving water resources. Cost-effective purification technologies to remove the highly toxic ammonia nitrogen (TAN), whose accumulation is produced by the fish metabolism, are fundamental to this goal. The high chloride concentration in seawater is at the same time an obstacle to conventional biological technologies and an opportunity to apply the chlorine-based oxidation of TAN. Thus, this work focuses on TAN oxidation by electrogenerated chlorine and considers alternative process configurations, (i) one-step electrochemical oxidation and, (ii) two-steps breakpoint oxidation after chlorine electrogeneration.The experimental assessment highlights that both process alternatives are effective in the total removal of ammonia and combined chlorine, when model SW with TAN concentration of 10 mg NH4+/L is treated. The specific energy intensity defined as kWh/mg NH4+ has been calculated for both configurations; being the two-stage process 2 times more energy efficient. Thus, this work provides the guidelines for the design of optimized electrochemical RAS water remediation with minimum energy consumption.