Assessment of new immobilized photocatalysts based on Rose Bengal for water and wastewater disinfection

Abstract

The aim of this study was to evaluate the water disinfection capability of new immobilized photocatalysts based on the organic photosensitizer Rose Bengal (RB) supported on glass wool and with two different photocatalyst load (RB_GW_0.22 and RB_GW_0.02). Tests were carried out under different operating conditions in a solar simulator at 30 W/m2 average UV-A irradiation. Isotonic water (IW) (with 9 g/L NaCl), simulated tap water (STW) and simulated urban wastewater effluent (SUWWE) spiked with Escherichia coli and Enterococcus faecalis (106 CFU/mL initial concentrations) were used as water model microbial strains. The mere effect of only irradiance was also investigated as reference of the photocatalytic performance over both bacteria. Results showed that RB_GW_0.22 presented high inactivation for E. faecalis, reaching 6 Log Reduction Value (LRV) in 2 min in IW and STW at pH 5 and 6 in comparison with only irradiance (60 min). In SUWWE, the effect of RB_GW_0.22 was also better for E. faecalis inactivation (60 min), compared to that produced in E. coli (120 min) and without the presence of the photocatalyst (where total inactivation was not achieved after 120 min of treatment). Ecotoxicity (ISO 11348–3:2007) and phytotoxicity (EN ISO 18763:2020) tests of the treated water were also assessed and results showed any significant effect, concluding that the use of RB_GW_0.22 is a promising solar photocatalytic treatment for urban wastewater reclamation and reuse.