Application of O3 and O3 /H2O2 for post-treatment of horizontal-flow anaerobic immobilized biomass (HAIB) effluent, treating hospital wastewater

Introduction: In recent years, the "emerging pollutants" in urban, industrial, and surface water bodies have called the attention worldwide. In many cases, these substances correspond to pollutants that have not been yet regulated by the environmental authorities. Hospitals are considered the main source of these contaminants as a result of different activities. However, there is no consensus about the appropriate treatments for removing this kind of pollutants in the wastewaters; independent conventional biological processes do not reach the desirable values of discharge limits. Advanced oxidation processes (AOP) are known as an appropriate technology, not only to improve the biodegradability of recalcitrant compounds, but also to contribute to the removal of certain substances that are difficult to treat during the biological process. Objective: Thus, this study evaluated the application of O3z and O3 /H2O2 to the effluent of an anaerobic horizontal flow reactor and immobilized biomass (HAIB). Methodology: The oxidizers were applied in a lab-scale batch borosilicate glass reactor. The reaction time was 60 min and samples were taken at intervals of 15 min. Parameters such as absorbance at UV254, biodegradability ratio expressed as COD/BOD5, and color as VIS436 were measured. All samples were analyzed in duplicate. Results. The results showed that the application of Ozone and O3/H2O2 results in an increase in the biodegradability of 25% and 67% respectively. Concerning color, an efficiency of 85 % for Ozone and 100 % for O3 /H2O2 was observed. Besides, the AOPs applied also showed their effectiveness in removing aromatic organics, removing 40 to 50% of UV254. Conclusions: Finally, it is important to mention that the application of advanced oxidation processes as a post-treatment of anaerobic effluents increases biodegradability mainly due to the transformation suffered by recalcitrant compounds.