On-line control of a SBR system for nitrogen removal from industrial wastewater

In this study, laboratory-scale experiments were conducted applying the SBR activated sludge process to a wastewater from a wood factory operating on plywood production. Due to the fact that the wastewater is characterised wi th a high concentration of ammonia, the aim was to evaluate the nitrogen re moval process with SBR system operating with a on-line control of ORP, pH a nd DO. The complete ammonia removal corresponded exactly to the "Ammonia Va lley" in the pH versus time graphic. The ammonia removal efficiency in SBR was 99% at 20 degreesC. The denitrification reaction was completed when in the ORP versus time graphic appeared the "Nitrate Knee". From the experimen tal results the optimisation of the SBR cycle allowed the doubling of the a pplied load with respect to a not optimised cycle (performed in the same vo lume reactor), without a decrease in the removal efficiency. Moreover, the possibility of stopping the aeration just after the appearance of the Ammon ia Valley allows an energy saving. The easy operation and the low cost make the SBR system an interesting option for the biological pre-treatment of p lywood industry to be discharged into surface water.