Nitrate removal from the effluent of a fertilizer industry using a bioreactor packed with immobilized cells of Pseudomonas stutzeri and Comamonas testosteroni

A bioreactor for the removal of nitrate nitrogen (NO3-N) from industrial effluent is described which is comprised of a glass column (60 cm x 6 cm) packed with alginate beads containing denitrifying organisms Pseudomonas stutzeri and Comamonas testosteroni. The effluent containing high concentrations of nitrate ( 600 - 950 mg l(-1)) from the fertilizer industry and fusel oil ( methanol as a major component) as organic carbon were used in the process. The reactor is operated in the continuous mode by injecting the pretreated nitrate-containing effluent at the top of the column. The Hydraulic retention time (HRT) was adjusted by changing the flow rates. When nitrate-containing wastewater was treated with immobilized cells, the nitrate removal rate reached a maximum 1.66 +/- 0.07 Kg NO3-N m(-3) d(-1) at an influent NO3-N concentration of 850 mg NO3- N l(-1) within 12 h. The denitrification activity of the immobilized cells was compared with that of the free cells.