Key-elements Affecting The Growth And Metabolism Of Glycogen Accumulating Organisms And The Preliminary Studies On Polyhydroxyalkanoates Synthesis

Glycogen accumulating organisms (GAOs) were a kind of microbe which coexisted with phosphorus accumulating organisms (PAOs) in the biological Wastewater treatment process. Under anaerobic condition GAOs uptake volatile fatty acids (VFAs) to synthesize poly-β-hydroxyalkanoates (PHA) but do not release phosphate; and under aerobic condition GAOs degrade PHA but do not uptake phosphate, so GAOs do not contribute to the phosphate removal in the Wastewater treatment. Recently, as many people showed more concerns about environment protection and sustainable development, especially the unique complete biodegradablity of biodegradable plastic, the study on the biological synthesis of biodegradable plastic has become a hot topic. PHA is one kind of biodegradable plastic, but its high production cost limits the wide application of PHA. The method of employing the activated sludge enriched with GAOs to produce PHA could reduce the production cost effectively.Five bench-scale SBRs were operated to cultivate five kinds of activated sludge enriched with GAOs. The long-term and short-term effects of different propionic/acetic acid ratio and initial pH on the anaerobic and aerobic transformations of GAOs were studied. The biomass acclimated with lower propionic/acetic acid ratio Wastewater for a long term synthesized more PHA and degraded more glycogen in the anaerobic phase; and degraded more PHA and synthesized more glycogen in the following aerobic phase with a higher microbial dehydrogenase activity and a faster microbial growth rate. At the same time, for the biomass acclimated long term with the same concentrations of acetic acid and propionic acid, the acetic acid initial uptake rate would be faster than the propionic acid. The results also showed that GAOs could utilize acetic acid without acclimation and the short-term increase of propionic/acetic acid ratio can inhibit the proliferation of GAOs in EBPR system. The biomass acclimated long term with higher initial pH synthesized more PHA and degraded more glycogen in the anaerobic phase; and degraded more PHA and...