Production of polyhydroxyalkanoates by a mixed culture in a sequencing batch reactor: the use of propionate as carbon source

In this work, sludge adapted to anaerobic/aerobic conditions, AN/AE, showing a high capacity of P accumulation, was submitted to aerobic dynamic substrate feeding (ADF). The fermenter was operated as a Sequencing Batch Reactor, with propionate as carbon substrate. Propionate is an important waste product from several industrial processes that can be valued, using it as a precursor for hydroxyvalerate in PHA production. Under the operational conditions used, apart from 3-hydroxyvalerate as its major component, 3-hydroxy-2-methylvalerate, 2-hydroxyisovalerate and 4-oxovalerate were also produced. A second reactor operated under the same conditions was adapted for the use of acetate as carbon substrate. The global metabolism of the organisms involved on PHA production, utilizing acetate or propionate, was studied using in vivo 13C Nuclear Magnetic Resonance (NMR).