Improvement of photocatalytic and photo-disinfection of wastewater using natural photosensitizer: stinging nettle (Urtica dioica) leaves extract.

This study focuses on the improvement of photocatalytic treatment using natural photosensitizer extracted from nettle (Urtica dioica) leaves. The nettle aqueous extract (NAE) have shown antimicrobial activity against pathogenic bacteria. In addition, it contains molecules that can absorb in ultraviolet (UV) and visible region. This property was used to enhance nanobiocide activity of titanium dioxide nanoparticles (TiO2-NPs). For solar application, this NP has the limit to absorb in UV region. To monitor the impact of NAE on different photodisinfection treatments, the quencher coefficients of bacterial cutivability (Qn), and bacterial viability (Qp) were determined. The exploration of bacterial viability was done basing on the determination of phage amplification rate in relation with post-treated bacteria. Results showed a relative retention of bacterial viability compared to bacterial cultivability after photocatalytic treatment. In addition, there is an increase in quencher coefficients even without sun light illumination. The photoincitation of photcatalytic complex allowed the reduction of 99.99% of bacterial cultivability and 99.9% of bacterial viability. These results could open a new horizon to valorize the potential use natural extracts to enhance tertiary wastewater performance, and to contribute in the establishment of reliable green water disinfection process.