Disinfection of greywater pre-treated by constructed wetlands using photo-Fenton: Influence of pH on the decay of Pseudomonas aeruginosa

• Systems with pH adjustment were the most efficient in disinfection and clarification.
• The H2O2/UV system proved to be very promising to greywater reuse.
• P. aeruginosa inactivation showed a log-linear followed tail behaviour model.
• Fenton and photo-Fenton systems showed higher levels of colour and turbidity.

The photo-Fenton system has proved to be very effective in the treatment of wastewater for reuse recently. The aim of this study was to test the photo-Fenton system and other advanced oxidation processes for greywater disinfection, with the alternative indicator microorganism Pseudomonas aeruginosa. The hydrogen peroxide concentration at 150 and 25 mg L−1 was varied, keeping the Fe2+ concentration of 10 mg L−1 and adjusted the pH at 3 to compare with the natural pH of sample. The systems with pH adjustment were the most efficient in disinfection and clarification of greywater. To the high hydrogen peroxide concentration, there was no difference in the disinfection (all achieved total inactivation). However, the system H2O2/UV with concentration of 150 mg L−1 hydrogen peroxide gave results similar to systems with pH adjusted (more efficient). The hydrogen peroxide concentration was the main factor for inactivation and clarification exerting greater influence compared to pH adjustment.