Catalytic removal of sulfide by an immobilized sulfide-oxidase bioreactor

A bioreactor packed with chitosan immobilized sulfide-oxidase from Streptomyces species LD048 was developed to treat a liquid stream of sulfide. The inoculation system was composed of glass with a 0.7 L working volume and enzyme activity of 2 mmol S g−1 carrier. The sulfide removal efficiency was almost 100% when the volumetric loading was increased up to 3.9 mmol S L−1 h−1 at a space velocity of 18 h−1. The maximal elimination capacity was 22.1 mmol S L−1 h−1 with a space velocity of 72 h−1. When the aeration was increased from 0.05 to 0.1 L min−1, the average removal efficiency improved from 81% to 94%. A removal efficiency of 90% was obtained after 15 days of operation with a load rate of 8.9 mmol S L−1 h−1 and a space velocity of 14.28 h−1. An operational equation based on the ideal plug flow bioreactor and the Michaelis–Menten model predicted the performance of this bioreactor.