Demonstrating the feasibility of a novel solar photo-Fenton strategy for full-scale operationalization according to EU 2020/741 disinfection targets for water reuse

Abstract

A novel solar photo-Fenton strategy based on the simultaneous supply of Fe3+-NTA, H2O2 and NaOCl has been proven, for the first time, to meet the more restricted disinfection requirements set by the EU 2020/741 Regulation on wastewater reuse. Operational settings near to real conditions were considered to encourage future operationalization at full-scale. This novel approach, operating in continuous flow mode, has proceeded to effectively reduce Escherichia coli, Clostridium perfringens and MS2 coliphage, along with total coliforms (TC) and Enterococcus faecalis load, with total inactivation levels ≥ 5 log-units for E. coli, E. faecalis, and MS2, 4 log-units TC and 3.5 log-units C. perfringens. Despite validation targets for coliphages (≥6 log-units) and C. perfringens (≥5 log-units) were not attained, it appears feasible by lightly increasing NaOCl concentration. Additionally, the remaining E. coli load in the photoreactor's effluent was within the strictest EU 2020/741 monitoring threshold (≤10 CFU/100 mL). Therefore, the rearrangement of oxidants concentration should be further explored, as this new strategy is shown as a promising technology to address the challenge disinfection presented for full-scale operation. This showing a high potential to produce water that complies with the highest EU 2020/741 standards (Class A), with no additional adjustments required to produce water within the Classes with fewer restrictions (B, C, and D).