Evaluation of ozone-based oxidation and solar advanced oxidation treatment of greywater

Reclaiming non-conventional water sources such as greywater is gaining more attention in the light of current and expected water shortage due to the global trend of continued population growth, urbanization, and the impact of climate change. In this work, the degradation of organic matter measured as total organic carbon (TOC) and biochemical oxygen demand (BOD5) in real greywater samples using different ozone-based oxidation and solar advanced oxidation treatments was investigated in a custom-built glass tube reactor combined with a concentrated parabolic collector (CPC). The evaluated processes included ozonation (O3), solar ozonation (O3/solar irradiation), hydrogen peroxide oxidation (H2O2), hydrogen peroxide under solar irradiation (H2O2/solar irradiation), peroxonation (H2O2/O3), and solar peroxonation (H2O2/O3/solar irradiation). Combining different treatment methods with/without exposure to solar irradiation enhanced overall treatment efficiency. The efficiency of the examined processes followed the order: solar peroxonation > solar ozonation > peroxonation > ozonation, while the other processes showed a negligible effect. The highest TOC reduction (58.6 %) was observed using solar peroxonation at 41.7 mg O3/min and 0.2 H2O2/O3 molar ratio; the highest BOD5 reduction (29.4 %) was observed using solar peroxonation at 41.7 mg O3/min and 0.4 H2O2/O3 molar ratio. We conclude that low-cost advanced oxidation technologies can be effective to remove organic materials providing efficient greywater remediation for reuse applications.