Physicochemical processes as an alternative to biological removal of azoles from wastewater

Azoles such as climbazole, fluconazole, and tebuconazole are widely used antifungal agents in medical and agricultural applications. Due to their persistence and poor removal in conventional wastewater treatment processes, they are frequently detected in aquatic environments. This study evaluates and compares the efficiency of three treatment methods-biodegradation, electrooxidation, and photolysis-for the removal of these compounds. Climbazole was fully biodegraded within five weeks, while tebuconazole showed partial removal (50-60%), and fluconazole was barely affected (∼10%). Electrooxidation achieved over 90% removal of tebuconazole and fluconazole within 6 h, and complete removal of climbazole in 2 h. Photolysis was the most effective method, eliminating climbazole and tebuconazole within 10 min and ∼80% of fluconazole within 60 min. Although photolysis efficiency was slightly reduced in treated wastewater, it still outperformed the other methods. Three persistent photolysis by-products were identified for tebuconazole and fluconazole. Chronic toxicity analysis revealed that fluconazole's transformation products were more toxic to aquatic organisms than the parent compound. These findings highlight the potential of photolysis for efficient azole removal and emphasize the environmental risks associated with fluconazole degradation products.