Denitrification using a membrane‐immobolized biofilm

Denitrification using a membrane‐immobilized biofilm may offer a more economic nitrate removal method than conventional treatments. Immobilized bacterial cell technology was applied, on a bench scale, to the selective removal of nitrate from contaminated water, together with the segregation of denitrifying bacteria and the carbon energy source from the treated water. The two‐chambered reactor, with a microporous membrane for bacterial cell immobilization, performed at an average denitrification rate of 5,800 mg nitrate‐nitrogen (NO 3 − ‐N)/m 2 /d of membrane surface area. A carbon‐to‐nitrogen mass consumption ratio of 2.2 g organic carbon/gram nitrogen was observed, with a small degree of methanol contamination of the water being treated. A physical model for NO 3 − ‐N removal based on Fick's law and the measured diffusion coefficient of nitrate through the immobilization structure gave a good correlation with experimental results.