Comprehensive kinetics of electrochemically assisted ammonia removal in marine aquaculture recirculating systems

Abstract

This work reports a comprehensive kinetic analysis and modelling of the electrochemically assisted ammonia removal from marine aquaculture waters (RAS). The proposed model combines the kinetics of chlorine electro generation, experimentally determined, with the mechanism and kinetic parameters, taken from literature, of break point chlorination reactions involving aqueous chlorine (HClO and ClO-), total ammonia nitrogen (TAN as NH3 and NH4 +), and the chlorinated derivatives of ammonia (monochloramine (NH2C1), dichloramine (NHC12), and nitrogen trichloride (NC13)). The model has been validated with laboratory experiments, obtained in an electrochemical cell provided with Ti/RuO2 anode and Ti cathode, and working with model sea water in the range of operating variables [TAN]0 = 10-60 mg L-1 and j = 5 - 20 A m-2 ; good agreement between simulated and experimental data for the progress of ammonia and combined chlorine concentrations assesses the validity and robustness of the kinetic model. Thus, this study provides the tools to analyse, predict and explain ammonia removal performance in the electrochemical treatment of marine RAS water.