Contrast of VFA Driven and Inorganic Acid/Base Driven pH Changes Impacting Phosphorus Transformations in EBPR

Addition of acid resulted in high anaerobic phosphorus (P) releases both with or without the presence of volatile fatty acids (VFAs) for an EBPR biomass. There was also a subsequent increase in aerobic P release but such that there was a lower net P removals. NaOH addition reduced both anaerobic P release and aerobic P uptakes both with and without the presence of VFAs but did not improve net P removals. PHA quantity and type was virtually unaffected by pH in all the experiments and was a function of the VFA type received. Glycogen metabolism did not show entirely consistent trends but in the presence of VFAs acid pHs generally resulted in less glycogen biosynthesis. If VFAs were not present both acid and base addition slightly increased glycogen biosynthesis.