Metagenomic insights into virus removal performance of an algal-based wastewater treatment system utilizing Galdieria sulphuraria

Abstract

An algal wastewater treatment system capable of reducing dissolved organics, nutrients, and pathogenic bacteria to secondary discharge standards in a single step has been reported on previously. The current study evaluates pathogenic virus reduction in this algal wastewater treatment system and compares it with that in conventional wastewater treatment systems using culture- and nucleic acid-based quantitative methods and shotgun metagenomic sequencing technique. Log removal of somatic coliphages (3.13 ± 0.34), F-specific coliphages (1.23 ± 0.34), Enterovirus (1.05 ± 0.32), and Norovirus GI (1.49 ± 0.16) in the algal wastewater treatment system without any chlorination were comparable to those in the conventional wastewater treatment system with chlorination. While the virus community in the chlorinated effluent of the conventional system was diverse with ~250 species, only 14 discrete virus species were found in the unchlorinated effluent of the algal-based system, none of them pathogenic to humans. This study demonstrated the feasibility of the A-WWT system in delivering pathogenically-safe, high-quality effluent for disposal or beneficial reuse with minimal post-disinfectant demand.