Removal of acetate from NSSC sulphite pulp mill condensates using thermophilic bacteria

Treatment of sulphite mill condensates containing acetate and ammonia was studied using aerobic thermophilic bacteria at 65°C. A separate treatment at this relatively high temperature could save energy and decrease water consumption in the process. Experiments were carried out in packed bed bioreactors (vol. 0.1–0.3 dm³) using media based either on condensate or on ammonium acetate. Diatomaceous earth was superior to the other carrier materials tested (red brick, activated carbon, pumice). At 90% acetate removal, the acetate consumption rates were ca 0.7 and 0.5 g dm⁻³ h⁻¹ on ammonium acetate (acetate 5 g dm⁻³) and dilute condensate media (acetate 2 g dm⁻³), respectively. The corresponding dilution rates were 0.15 and 0.38 h⁻¹.