THE EFFECTS OF PROPIONIC VERSUS ACETIC ACID CONTENT OF DOMESTIC SEWAGE ON ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL

摘要

Enhanced Biological Phosphorus Removal was found to be superior for a Sequencing Batch Reactor (SBR)treating septic domestic wastewater with a propionic/acetic acid ratio of 2.12 (Propionic SBR) compared to aparallel and identical system with a propionic/acetic acid ratio of 0.145 (Acetic SBR). The Propionic SBRbiomass removed 10.65 mg phosphorus (P)/gVSS (s=0.68) compared to 8.20 mgP/gVSS (s=0.93) for theAcetic SBR. However the maximum Propionic SBR PHA content was 49.3 mgPHA/gVSS with a 3HV/3HBratio of 2.69. This was much lower than the Acetic SBR PHA content of 76.4 mgPHA/gVSS with a3HV/3HB ratio of 0.449. The stoichiometric relationship between PHA and P was significantly different forthe two populations studied. This was in spite of the fact that acetic acid gave superior results relative topropionic acid in batch experiments using Propionic SBR biomass. It is probable that while propionic acidwas less efficient for EBPR than acetic acid in pure biochemical terms, it was even less efficient fororganisms uninvolved in EBPR, giving it a stronger selective pressure favoring EBPR than acetic acid. Theselective pressure of the VFAs was more significant than biochemical processing.