Control and Nitrogen Load Estimation of Aerobic Stage in Full-Scale Sequencing Batch Reactor to Treat Strong Nitrogen Swine Wastewater

Three different control methods based on ORP and DO for determining aeration time were evaluated for swine wastewater treatment at full-scale SBR. For determining the Ending Point of Ammonia Oxidation (EPAO), the plateau in ORP profile, the derivative of DO, and absolute DO were tested. Below 0.5㎏ NH₄?-N/㎥ㆍday of influent loading rate, three control methods produced good results however, above this loading rate, only absolute DO method was feasible. The volumetric ammonia nitrogen load at the sub-cycle (㎏ NH₄?-N/㎥/sub-cycle) had an effect on the period of aeration. To put it more concretely, the higher loading rate required the longer ammonia nitrogen oxidation period. To estimate nitrogen load, the length of low DO period, which was defined as the required time to reach 3㎎ DO/l from the start of aeration, was the most proper parameter.