Integrated assessment of the elimination of particle-associated fecal indicators in algal–bacterial granule photobioreactors†

Two photo-sequencing batch reactors (PSBR) fed with real wastewater were evaluated to understand the elimination and particle association of fecal indicator bacteria (FIB) and coliphages. The average log₁₀ removal of E. coli and Enterococcus spp. were 3.2 and 2.9, respectively, for the PSBR with a low airflow rate of 0.2 LPM (PSBR-L), and 2.8 and 2.7, respectively, for the PSBR with a high airflow rate of 0.5 LPM (PSBR-H). The average log₁₀ removals of F-specific and somatic coliphages were 2.9 and 3.2, respectively, for the PSBR-L reactor, and 2.5 and 3.1, respectively, for the PSBR-H reactor. FIB had a maximum association on the 20–0.45 μm particles (46.1–63.3%), while the coliphages had the highest association on the 0.45–0.03 μm particles (44.7–51.2%). The dynamic adaptations in the microbial community structure (16S rRNA gene) were also investigated during the operation period. Genera involved in nutrient removal, such as Thauer spp., and Nitrospira spp., were detected across samples. The outcomes reveal the efficiency of photobioreactors in removing pathogen indicators from real wastewater.