Investigation of diclofenac degradation by microbial biosurfactants from real-time wastewater

Abstract

Microbial biosurfactants provide a sustainable solution by enhancing solubility and promoting the degradation of contaminants. The research explores the utilisation of waste cooking oil as a sustainable substrate for enhancing rhamnolipid biosurfactant production in Pseudomonas aeruginosa and its application on the removal of Diclofenac (DCF), a pharmaceutical contaminant from real-time wastewater. The optimised conditions led to a biomass yield of 6.7 g/L, critical micelle concentration (CMC) was determined to be 40 mg/L, and crude rhamnolipid production reached 7 g/L. The presence of glycosidic bonds was verified using Fourier transform infrared (FTIR) spectroscopy. At its CMC, the biosurfactants facilitated the complete removal of DCF within 48 hours. Toxicity analysis revealed that biosurfactants demonstrated lower phytotoxic effects, showcasing their biocompatibility. A comparative evaluation of treatment efficacy indicated that biosurfactants and chemical surfactants achieved complete DCF removal under UV-visible spectroscopy. Biosurfactant-induced degradation products with m/z values of 228 and 282 were identified using Liquid chromatography-mass spectrometry (LC-MS), indicating pathways involving de-chlorination and hydroxylation. The study implies the feasibility of biosurfactants as eco-friendly agents in removing pharmaceutical contaminants in wastewater, offering a sustainable approach towards environmental pollutants. © 2025 Indian Institute of Chemical Engineers.