Solar Advanced Oxidation Processes as disinfection tertiary treatments for real wastewater: implications for water reclamation.

Abstract

The aim of this study was to assess the disinfection of a real secondary effluent from a municipal

wastewater treatment plant using added H2O2 (20 and 50 mg L−1), TiO2 (100 mg L−1) and photo-Fenton

under natural solar radiation in compound parabolic collector photo-reactors. For this purpose, the

naturally occurring Escherichia coli, spores of sulphite-reducing clostridia (SRC), somatic coliphages

(SOMCPH) and F-specific RNA bacteriophages (FRNA) were tested before and along the different solar

treatments. Results for E. coli showed the different treatments efficiency rank: photo-Fenton pH 3 > H2O2

(20 mg L−1)/solar > TiO2/solar > solar photo-inactivation. On the other hand, for viral indicators the ranking

was: photo-Fenton pH 3 > TiO2/solar > H2O2 (20 mg L−1)/solar > solar photo-inactivation. SRC was the

most resistant indicator microorganism in all the evaluated processes. For the first time these solar processes

have been evaluated for naturally occurring conventional indicators such as E. coli and alternative

indicators such as SOMCPH and FRNA as viral indicators or spores of SRC as protozoan indicators. Some of

the tested solar photo-oxidation treatments have shown their capability to reduce E. coli concentrations

to a suitable level for water reuse (according to different reclaimed water guidelines) within affordable

treatment times.