Microalgae as biocatalyst in simultaneous photodegradation of antibiotics and hormones

BACKGROUND: Unregulated use of veterinary pharmaceuticals has caused environmental concerns such as ecotoxicity and development of genetic resistance in the microbial biosphere. Photocatalytic treatments, e.g. photo‐Fenton reaction, have been considered for their removal. In this work, substitution of the use of a chemical oxidant such as hydrogen peroxide (Fenton reaction) by organic molecules from sonicated microalgae biomass Chlorella sp, combined with Fe²⁺ and UV light, was used to evaluate the removal of antibiotic ciprofloxacin (CIP) and hormone 17β‐estradiol (E2) in synthetic wastewater. RESULTS: Removal of CIP was improved using only UV (71%), by adding Fe²⁺ at 0.54 mmol L⁻¹ (90.17%) and combining these with sonicated microalgae biomass (0.4 g L⁻¹), achieving >99% CIP removal and 75% E2 removal after 120 min of treatment. When the conditions were optimized, aiming to decrease the Fe²⁺ concentration and improve the removal of CIP, the optimal conditions were pH 7, sonicated microalgae biomass concentration 0.5 g L⁻¹ and 0.39 mmol L⁻¹ Fe²⁺, reaching 97 and 70% removal efficiency for CIP and E2 respectively; when microalgae biomass was not added, removal decreased to 90 and 57% respectively. CONCLUSION: Photodegradation with sonicated microalgae biomass has demonstrated to be an effective option to improve the removal of selected antibiotics and hormones from wastewater, considering that no acidification or costly reagents are needed for its optimization. © 2020 Society of Chemical Industry