Effects of CaCl2 freeze-drying and acidic solutions on the reusability of calcium alginate beads; and degradation of phenol by immobilized Acinetobacter sp. PR1

Abstract Applications of immobilization technology to wastewater treatment have achieved mixed results, that is, high degradation efficiency or good reusability. In this research, alginate was used as supporting material of immobilized beads to maintain high degradation efficiency. Applying CaCl2 freeze drying and acidic solutions led to the reusability of the beads. Ca-alginate beads can be reused for more than 21 cycles of repeated CaCl2 freeze drying and 16 cycles of treatment at pH 3. About 60% of the cells survived after CaCl2 freeze drying. Scanning electron microscopy images of the reused Ca-alginate beads demonstrated the highly porous carrier of the Ca alginate. Finally, the freeze-dried beads that were hardened first by polyethyleneimine were used for 30 days before the next CaCl2 freeze drying. The freeze drying frequency decreased from three cycles (about 40 hours) to 30 days.