Nitrogen-Limitation-Induced Carbon and Phosphorus Fluxes in Anaerobic/Aerobic Sequencing Batch Reactors
Wu, G. and Rodgers, M., National University of Ireland
(free)
Enhanced biological phosphorus removal (EBPR) has been applied widely in wastewater treatment
plants. However, deterioration or failure of EBPR often happens because: (i) of the dominance of glycogen-accumulating organisms (Type I), or (ii) there is no anaerobic carbon uptake or phosphorus
release (Type II). In this study, carbon and phosphorus fluxes under nitrogen-limitation conditions in
anaerobic/aerobic sequencing batch reactors (SBR10 at 10 oC and SBR20 at 20 oC) without EBPR (Type II) were examined. Zoogloea sp. was detected in all samples from both reactors using the fingerprinting technique. In spite of the absence of EBPR, the biomass total phosphorus content of 3.8% in SBR10 and 4.8% in SBR20 was still high. Phosphorus removal could have occurred through biomass assimilation, chemical precipitation (including a precursor nucleation phase and then a crystallization phase), and contribution from extracellular polymeric substances. Under nitrogenlimitation conditions, the polyhydroxybutyrate content increased from 13.9% to 32.7% in SBR10 and from 8.3% to 28.8% in SBR20; while the intracellular carbohydrate content was 9.9% in SBR10 and 9.6% in SBR20, and the extracellular carbohydrate content was 7.8% in SBR10 and 6.0% in SBR20.
KEY WORDS: Carbon metabolism; Enhanced biological phosphorus removal; Extracellular polymeric substances; Nitrogen limitation; Phosphorus precipitation; Polyhydroxybutyrate; Zoogloea sp.
