Effect of the Cellular Age of the Cyanobacterium Microcystis aeruginosa on the Efficacy of the UV/H2O2 Oxidative Process for Water Treatment

Cyanobacteria, particularly Microcystis aeruginosa, can form dense blooms that impair water quality, and conventional treatment methods often fail to remove them effectively. This study evaluated the impact of cell age on the performance of the UV/H2O2 advanced oxidation process against M. aeruginosa. Cultures of M. aeruginosa were monitored over 64 days at an initial culture density of 1.20 × 106 cells mL−1. For the UV/H2O2 experiments, cells were adjusted to a density of 5.00 × 105 cells mL−1, and the growth and oxidative experiments were monitored using parameters such as hydrogen peroxide decay concentration, optical density at 730 nm (OD730), cell density, and dissolved organic carbon (DOC). The hydrogen peroxide (H2O2) dosages used were 20 mg L−1 and 50 mg L−1, and the results showed that despite varying cell ages, H2O2 consumption remained stable at both dosages. While optical density and cell count indicate total cell removal, DOC levels increased due to cell lysis, resulting in contributions from both intracellular and extracellular fractions. A linear correlation was found between cell density and OD730, and between total DOC and cell density. In conclusion, cell age did not influence the effectiveness of the UV/H2O2 process under the conditions tested. These findings indicate that UV/H2O2 can be an effective approach for managing cyanobacterial blooms in water treatment systems, with its performance being unaffected by cell age.