Predatory bacteria in combination with solar disinfection and solar photocatalysis for the treatment of rainwater

• Published in: Water research (Oxford) Vol. 169; p. 115281
• Main Authors: Waso, M., Khan, S., Singh, A., McMichael, S., Ahmed, W., Fernández-Ibáñez, P., Byrne, J.A., Khan, W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2020
• Subjects: Bacteria; Bdellovibrio bacteriovorus; Biological pre-treatment; Disinfection; Harvested rainwater; Photocatalysis; Solar disinfection; Sunlight; Titanium; Water Microbiology; Water Purification; Solar disinfection; Harvested rainwater; Biological pre-treatment; Photocatalysis; Bdellovibrio bacteriovorus
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2019.115281

The predatory bacterium, Bdellovibrio bacteriovorus, was applied as a biological pre-treatment to solar disinfection and solar photocatalytic disinfection for rainwater treatment. The photocatalyst used was immobilised titanium-dioxide reduced graphene oxide. The pre-treatment followed by solar photocatalysis for 120 min under natural sunlight reduced the viable counts of Klebsiella pneumoniae from 2.00 × 109 colony forming units (CFU)/mL to below the detection limit (BDL) (<1 CFU/100 μL). Correspondingly, ethidium monoazide bromide quantitative PCR analysis indicated a high total log reduction in K. pneumoniae gene copies (GC)/mL (5.85 logs after solar photocatalysis for 240 min). In contrast, solar disinfection and solar photocatalysis without the biological pre-treatment were more effective for Enterococcus faecium disinfection as the viable counts of E. faecium were reduced by 8.00 logs (from 1.00 × 108 CFU/mL to BDL) and the gene copies were reduced by ∼3.39 logs (from 2.09 × 106 GC/mL to ∼9.00 × 102 GC/mL) after 240 min of treatment. Predatory bacteria can be applied as a pre-treatment to solar disinfection and solar photocatalytic treatment to enhance the removal efficiency of Gram-negative bacteria, which is crucial for the development of a targeted water treatment approach. [Display omitted] •Pre-treatment with predatory bacteria effectively disinfected Gram-negative bacteria.•Solar disinfection/photocatalysis effectively disinfected Gram-positive bacteria.•Predatory bacteria could serve as an additional strategy to optimise rainwater treatment.