Abstract

The purpose of this study was to investigate the immobilization of denitrifying bacteria on microbial cellulose (MC) for biological denitrification. A novel denitrifying bacterium, Pseudomonas stutzeri, was immobilized in microbial cellulose and introduced into an up flow packed bed reactor in order to remove nitrate from synthetic influent. The MC presented the high biomass concentration throughout the experiment, achieving 3.4 mg biomass/g support. The efficiency of the system for denitrification was tested under different running conditions. Complete biological denitrification of the synthetic effluent was achieved at low hydraulic residence times, less than 4 h, and high nitrate concentration (200 mg NO3-N/L). The immobilization of the bacterium in MC increased the adsorption capacity, decreased the cell leakage from the beads, resulted in higher activity of the immobilized cells, and allowed better operational control.