Evaluation of Bench-Scale Sequencing Batch Reactor Swine Waste Treatment Under Continuous and Cyclic Aeration

Abstract

The objectives of this project were to develop operating conditions for a bench-scale sequencing batch reactor to match the design of a full-scale sequencing batch reactor system for treating swine waste and to determine the effects of continuous, low oxygen versus cyclic aeration schemes on sequencing batch reactor system performance. The low aeration technique was intended to develop conditions for low oxygen nitrification and simultaneous nitrification and denitrification so that a comparison could be made to a typical cyclic aeration reactor for biological nitrogen and phosphorus removal. The performance of the two reactor configurations was measured by the settling efficiency, mass removal efficiency, and accumulation of chemical oxygen demand (COD), suspended solids (SS), total Kjeldahl nitrogen (TKN), and total phosphorus (TP). The performance of the reactors did not meet expectations due to excessive loading and source inconsistency. Operational changes to the solids wasting mechanism and to the cyclic aeration system were made during the experiment in an attempt to stimulate reactor performance, which provided insight into the responses of the two types of reactors to these changes. The performance of the continuous aeration reactors met or exceeded the performance of the cyclic aeration reactors, while receiving a 73% lower supply of oxygen. The results support the potential for equipment and energy savings by utilizing low-oxygen continuous aeration for the treatment of swine waste with sequencing batch reactors.