Effective Bead Preparation of Coimmobilized Methanogenic and Methanotrophic Bacteria for Tetrachloroethene Degradation

Three types of coimmobilized methanogenic and methanotrophic bacterial beads – Ca-alginate, Ba-alginate, and Ca-alginate chitosan – were used for tetrachloroethene (PCE) degradation. For the purpose of effective preparation of coimmobilized bacterial beads, the diameter and broken-loading of beads were measured. The activity tests to find the optimal bacteria concentration in the bead were performed. It was found that Ba-alginate beads had superiority in bacterial growth and the degree of strength of beads from the diameter and broken-loading tests. Also, it was shown that it is most effective to add 200 mL of methanogens into 500 mL of 2% alginate solution and 20 mL of methanotrophs into 500 mL to 2% alginate solution. When methanogens and methanotrophs were applied with the Ba-alginate bead in the actual dechlorination of PCE, the biological PCE dechlorination rate was 92%, and there was highly effective degradation of PCE based on the coimmobilized bead. Additionally, relation to the diameter (X) and broken-loading (Y) of the Ba-alginate bead was derived following equation, Y = 438.02 exp(–1.4815 X).