Rainwater treatment by solar galvanic system (Mg/Cu): effect of UV radiation on nitrate/ammonia removal and...

The high degree of urbanization and industrialization has led to the generation of nitrogenous matter in rainwater, which poses a significant health risk when rainwater is used for drinking purposes. A solar galvanic system was fabricated using a copper and magnesium (1:1) electrode with the goal to study the removal of nitrates and ammonia from rainwater. Surface response methodology with the flow rate (3.17-8.82 mL·min^-1) and supporting electrolyte concentration (0.004 M-0.010 M sea salt) as the operating variables was used to determine the optimal conditions (0.011 and 4.7 mL·min^-1) of this process. Solar radiation at 167.72 kJ·L^-1 induced the photocatalytic degradation of nitrates, and the degradation of ammoniacal nitrogen was promoted by the generation of oxidizing agents, such as the $H{O}^{.}$ radical. The removal of nitrate and ammoniacal nitrogen, respectively, was fitted to the Behnajady-Modirshahla-Ghanbery (BMG) two-stage model. Computational fluid dynamics (CFD) modelling of the thermal and hydrodynamic processes showed that a temperature of 343.15 K and flow rate of 3.17 mL·min^-1 enabled 81.49% nitrate removal, whereas a flow rate of 6 mL·min^-1 enabled 55% removal of ammoniacal nitrogen. The residual amounts of both species complied with permissible standard limits.