BIOLOGICAL MECHANISM OF ACETATE UPTAKE MEDIATED BY CARBOHYDRATE CONSUMPTION IN EXCESS PHOSPHORUS REMOVAL SYSTEMS

Four anaerobic batch experiments were conducted with anaerobic-aerobic acclimatized sludge fed with acetate. Samples were analyzed for COD and acetate uptake, P release, CO//2 production and for intracellular carbohydrate, protein and PHB content. PHB was synthesized by the sludge corresponding to acetate and COD uptake, along with orthophosphate release. Protein synthesis was not observed but intracellular carbohydrates were consumed. From the results, it is concluded that intracellular carbohydrates are consumed via the Embden-Meyerhoff-Paranas pathway and converted to acetyl-CoA, which provides NADH required for PHB synthesis. As observed carbohydrate consumption is greater than theoretical requirement for PHB synthesis, the consequent excess NADH available makes the possibility of some acetyl-CoA being circulated through the TCA cycle very remote.