Oxygen recharge and ammonia stripping capabilities of various closed culture configurations

A packed tower (trickling filter), empty, half full and full of a medium (styrofoam packing material) and a rotating biological contactor (RBC, rotating disc) were tested at various recirculating flow rates, with and without supplemental aeration, to determine oxygen recharge and ammonia stripping capabilities. Oxygen recharge capabilities increased with increasing flow rates, but at different rates for each filter. Oxygen recharge efficiencies decreased as flow rates increased in the half full and empty towers, were about constant for the full tower and increased in the RBC. Oxygen recharge capabilities were significantly increased with the addition of surface agitation; greater than the sum of the component contributions. With supplemental aeration, the full tower with a recirculation flow of 45·4 liters/min was most efficient and capable of supplying the most oxygen. Ammonia stripping was found to be insignificant in all systems tested.