Biological denitrification in a continuous flow membrane reactor

Biological denitrification in a bench-scale continuous flow membrane reactor has been investigated. The nitrate-laden water treated was separated from the suspended denitrifying culture by a 0.02 μm average pore diameter membrane. Equal pressure was maintained across the membrane and nitrate was removed by molecular diffusion through the membrane and into the denitrifying culture. A nitrate removal efficiency of approximately 90% or a flux of 4 g NO3−–N/m2/d of membrane area was achieved with an influent concentration of 20 mg/l NO3−–N. A mathematical model was developed to approximate system performance. Predicted effluent concentrations for the experiments conducted were 5.7, 9.5, 11.7 and 17.6 mg/l NO3−–N. The respective measured effluent concentrations were 2.3, 6.0, 9.0 and 16.0 mg/l NO3−–N.