Immobilization of a microbial consortium on Ca-alginate enhances degradation of cationic surfactants in flasks and bioreactor

Free cells and Ca-alginate encapsulated cells of Aeromonas hydrophila MFB03 removed in shake flasks up to 65% of tetradecyltrimethylammonium bromide (TTAB) 30 mg l−1. While planktonic cells were unable to utilize 50 mg l−1 benzalkonium chloride (BAC) after 48 h of incubation, the immobilized cells of A. hydrophila MFB03 removed up to 90% of BAC (25–210 mg l−1) in the same period. A microbial immobilized consortium formed by A. hydrophila MFB03 and Pseudomonas putida A (ATCC 12633) was able to degrade, after 24–30 h, 65% of TTAB and 100% of BAC, both added at 50 mg l−1. BAC was completely removed by the consortium encapsulated in a stirred tank bioreactor at 30 °C, 100 rpm and 0.024 g beads ml−1 of medium, after 12 h of incubation; reaching a degradation rate five times greater than the one obtained in shake flasks (0.415 vs. 0.089 mg−1 h−1, respectively). The system completely removed, with the same efficiency, 50 mg l−1 of BAC for 3 consecutive cycles. These results indicate that the use of Ca-alginate beads containing cells of the consortium can be considered a proper method to achieve degradation of cationic surfactants.