UV‐B Irradiation Effect on Microalgae Performance in the Remediation of Effluent Derived from the Cigarette Butt Cleaning Process

In this study, the potential of ultraviolet B (UV‐B) radiation to alleviate the effects of pollutants in cigarette butt wastewater (CBW) was investigated using different Chlorella sorokiniana strains (F4, R1 and LG1). Microalgae were treated with UV‐B (1.7 Wm−2) for 3 days prior to their exposure to CBW and then incubated for 4 days in the absence or presence of UV‐B. UV‐B‐untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments and non‐enzymatic antioxidants, as well as nicotine and nicotyrine removal, were evaluated in 7‐day cultures. UV‐B treatments did not negatively impact algal chlorophyll or carotenoid production. UV‐B acclimation was strain‐dependent, correlating with native environment adaptations and genetic constitutions. UV‐B as a pretreatment had long‐term positive effects on nonenzymatic antioxidant capacity. However, LG1 needed more time to readjust the pro‐oxidant/antioxidant balance, as it was the most UV‐B‐sensitive. Phenolic compounds played an important role in the antioxidant system response to UV‐B, while flavonoids did not contribute to the total antioxidant capacity. Although cross‐resistance between UV‐B and CBW was observed in F4 and R1, only R1 showed nicotine/nicotyrine catabolism induction due to UV‐B. Overall, the results suggest that UV‐B activates defense pathways associated with resistance or tolerance to nicotine and nicotyrine.