Effect of feeding strategy on the performance of sequencing batch reactor with dual anoxic feedings for swine wastewater treatment.

Two feeding ratios, 3:1 (RUN I) and 2:1 (RUN II), were experimented to investigate their effect on removal of nitrogen, phosphorus, organic matter, and on the trends of oxidization-reduction potential (ORP) and pH in sequencing batch reactors (SBR) with dual anoxic feedings of swine wastewater. Results showed for both runs, the feeding ratio had a more significant effect on the removal of phosphorus and nitrogen than on COD in the operating cycle. As compared to RUN I, the removal of nitrogen and phosphorus was enhanced in RUN II. In addition, the optimal feeding ratio greater than 1:1 for SBR with dual anoxic feedings can be determined with reference to the decreasing range of ORP following the primary feeding, and the denitrification-associated ORP bending point in the second non-aeration phase. 1.