Nitrogen removal from swine wastewater in activated sludge systems using an ASM for continuous and intermittent aeration

Abstract

An ASM-type model considering BOD and N removal was implemented including nitrite as intermediate, free ammonia and free nitrous acid as potential inhibitors and temperature as process parameter during swine wastewater treatment. Simulations were performed at various conditions: continuous and intermittent aeration; influent swine wastewater BOD/N ratio of 2, 3 and 4. Under continuous aeration and low DO, N was mainly removed through the nitrite short cut in simultaneous nitrification-denitrification. Under intermittent aeration, N was removed at broader DO conditions during aeration than previously assessed for continuous aeration. In both aeration conditions, critical DO control was required to achieve satisfactory N removal, particularly when the BOD/N ratio of the wastewater was set at 2. This study assesses those conditions needed to meet the N effluent standards in AS swine wastewater treatment plants, and to identify those cases when post-treatment will be needed