[Denitrifying phosphorus-accumulating SBR combined with low-intensity aeration technology for piggery wastewater...

The wastewater from animal farms in China is threatening the quality and security of local water environment. In the laboratory scale, a traditional SBR (A/O) and a denitrifying phosphorus-accumulating organisms (DNPAO) sequencing batch reactor (SBR) in biologically removing nutrients and organic matters from swine manure were investigated in this study. When piggery wastewater was directly treated with a traditional SBR, the efficiency was low with unstable working state, the reduction of TN, TP and BOD5 reached 89.08%, 86.04% and 93.88%, respectively. While it performs a good effect in treating high density of piggery wastewater using DNPAO SBR technology, with the help of low-density aeration, two-step of influent feeding and two circulations of anaerobic-anoxic-anaerobic-anoxic (An/Ax2), the reduction of TN, TP and BOD5 reached the maximums of 93.95%, 99.26% and 99.93%, respectively. The specific operation of (An/Ax2) SBR contributed both low concentrations and limited export loads of NO3-. The temporal curves of ORP, pH and DO over time could be indicators for simultaneous removals of nitrogen and phosphorus along with biodegradation of organic matter during this specific SBR running. A pilot-scale investigation was recommended to further testify the feasibility and efficiency of this kind of SBR under the real-world condition.