High BPA removal by immobilized crude laccase in a batch fluidized bed bioreactor

Abstract

In this work, the efficiency of immobilized crude laccase for the biodegradation of the phenolic endocrine disruptor bisphenol A (BPA) was investigated. The experiments were carried out in shake-flask scale and fluidized bed bioreactor (FBB) scale. Firstly, the optimization of BPA biodegradation by free and immobilized crude laccase was performed in shake-flask scale. For this, the effect of different operational conditions, namely temperature, pH, laccase activity and BPA concentration, was evaluated for a reaction time of 2 h. It was shown that under optimized conditions (30 °C, pH 5, 20 mg L−1 BPA, 1000 U L−1 free crude laccase and 1500 U L−1 immobilized crude laccase), BPA was totally removed (100% by free crude laccase and 99.6% by immobilized crude laccase from the aqueous solution). In addition, a good biodegradation efficiency of about 77% by immobilized crude laccase was achieved for higher BPA concentrations (100 mg L−1) at shake-flask scale. Finally, a novel approach consisting of an FBB with cross-linked-entrapped crude laccase led to a BPA degradation higher than 75% after the third successive cycle with increasing BPA concentrations (60, 80 and 100 mg L−1 for the 1st, 2nd and 3rd cycle, respectively). These results showed the operational stability of the cross-linked entrapped crude laccase during successive batches of BPA degradation.