Biodegradation of bisphenol A by alginate immobilized Phanerochaete chrysosporium beads: Continuous cyclic treatment and degradation pathway analysis

The wide application of biodegradation technology makes it particularly significant to use immobilized microorganisms to achieve continuous degradation of pollutants. In this study, the performance of Ca-alginate (CA) immobilized Phanerochaete chrysosporium beads in a consecutive biocycle treatment of bisphenol A (BPA) effluent was researched. The effects of initial BPA concentration, biomass dosage, pH and curing time were investigated. Results showed that CA-immobilized P. chrysosporium can be successive cycle at least 9 times (12 h each), and each time the removal efficiency of BPA reached 100%. The degradation process of BPA in the treatment process was investigated. According to the analyses of glucose, ammonia nitrogen, total nitrogen, extracellular proteins and biomass, it was found that consumed carbon and nitrogen sources were used for the rapid growth of fungal hyphae and the synthesis of a series of proteins. These extracellular proteins can be utilized as a nitrogen source by P. chrysosporium, and played a key role in the removal of BPA. Biodegradation process followed the pseudofirst-order kinetics. Moreover, intermediates in the BPA degradation process were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS), and three possible degradation pathways were proposed. This strategy presented in the study provides a convenient and efficient biological method for the continuous treatment of BPA effluent.