Effect of a Humus Soil Side-Stream Reactor (HSR) on the Bacterial Characteristics in Enhanced Biological Phosphorus Removal Process

Abstract

Three enhanced phosphorus removal processes, each with a sequencing batch reactor (SBR), one with a humus soil side-stream reactor, one with an anaerobic side-stream reactor, and one without a side stream reactor (used as a conventional SBR process), designated as HS-SBR, A-SBR, and C-SBR, respectively, were operated and compared for the treatment of municipal sewage in laboratory scale. Compared with the total phosphorus (TP) removal efficiency of 68.3% obtained in the C-SBR, the TP removal efficiency in the A-SBR was only 53.2%, while in the HS-SBR, it increased to 85.6%. This observation suggested that the anaerobic side-stream reactor repressed TP removal in the system, while the humus soil side-stream reactor improved the TP removal. The detailed biochemical microbial analysis showed that the anaerobic side-stream reactor inhibited the TP removal activity through the repression of the polyphosphate kinase activity in the A-SBR, while the humus soil side-stream reactor improved the TP removal through improving the growth of polyphosphate-accumulating organisms and the activity of polyphosphate kinase, and inhibiting the growth of glycogen accumulating organisms in the HS-SBR. It was further speculated that humus soil in the humus soil side-stream reactor influenced the metabolism of PAOs and GAOs in the SBR.