Enhanced biological phosphorus removal in a sequencing batch reactor supplied with glucose as a sole carbon source

Abstract

Metabolism of enhanced biological phosphorus removal (EBPR) in an anaerobic/aerobic sequencing batch reactor (SBR) was investigated when glucose was supplied as, a sole carbon source. There have been several reports claiming that the EBPR could not be accomplished with glucose feed as a carbon source due to the dominating growth of so-called "G-bacteria" which do not accumulate polyphosphate and take up glucose without ortho-phosphate release under anaerobic condition. However, in our work, high EBPR could be achieved even with the use of glucose as a sole carbon source following completely different mechanisms From previous reports. Glucose disappearance and glycogen accumulation rapidly occurred, which coincided with other reports. But the release of ortho-phosphate and synthesis of poly 3-hydoxy alkanoic acids (PHAs) were related to total organic carbon (TOC) concentration rather than glucose concentration. The fate of glucose in annerobic/aerobic stags H-as investigated by supplying all C-13-labelled glucose at the beginning of anaerobic stage which was traced by C-13-NMR spectroscopy. Results showed that the EBPR with glucose supply was accomplished at least by two kinds of microbial populations, a lactic acid producing organism (LPO) and a polyphosphate accumulating organism (PAO). During the anaerobic stage, about 0.42-C mmol of PHAs was synthesized from 1 C-mmol of glucose while 0.12 P-mmol of phosphate was released at pH 6.9. The amount of phosphate release was proportional to the FH value. The amount of PHAs synthesized was less than the amount of glucose added since glucose was converted to the other storage compound (inferred as lactic acid polymer) by the LPO in addition to the PHAs by PAO. During the aerobic phase, PHAs and storage compounds in cells were metabolized and phosphate uptake occurred. In this work, a probable metabolic pathway of PHA synthesis and phosphorus removal was proposed in a SBR supplied with glucose as a sole carbon source. (C) 2000 Elsevier Science Ltd. hll rights reserved.