Characteristics of Nitrogen and Phosphorus Removal by a Sequencing Batch Reactor

The characteristics of nitrogen and phosphorus removal was investigated in a sequencing batch reactor (SBR) with intermittent aeration. The operating cycle of SBR consisted of 1 h 30 min anaerobic, 1 h aerobic, 1 h anoxic, 20 min aerobic, 1 h anoxic and 20 min aerobic. Comparing with original anaerobic/aerobic mode, the oxygen supply could be decreased about 44%. Removal efficiencies of COD, total nitrogen and phosphorus were 88%, 89% and 100%, respectively. Then, the endogenous denitrification and the denitrifying phosphorous removal by poly-hydroxyalkanoates (PHAs) oxidation were investigated. It was found that the anoxic denitrification can work with PHAs utilized with or without the phosphate in both reactors, and the rates of denitrification and the PHAs utilized of the reactors were very similar. It's meaningful to study on the potential connection between the nitrifying bacteria and DPAOs, and attempt enrich DPAOs from nitrifying bacteria in future.