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 × 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⁻³d⁻¹ at an influent NO₃-N concentration of 850 mg NO_3M-N l⁻¹within 12 h. The denitrification activity of the immobilized cells was compared with that of the free cells. [ABSTRACT FROM AUTHOR]