Influence of Different Culture Selection Methods on Polyhydroxyalkanoate Production at Short-term Biomass Enrichment

Abstract

In this study, the potential of four different culture selection methods under short-term enrichment time (STE) to accumulate PHA-producing bacteria in mixed activated sludge was compared and the most efficient culture selection method was introduced. This means, PHA-producing microbial community was firstly enriched in a sequencing batch bioreactor (SBR) with four different selection methods including an anaerobic-aerobic process (SBR1), a fully aerobic batch process (SBR2), an uncoupled carbon and nitrogen feeding regime (SBR3) and aerobic/anoxic process (SBR4). In the next step, cellular PHA content was maximized in a fed-batch accumulator. From the obtained results, PHA could be accumulated up to 13.2, 10.8, 22.36, and 6 % (mg-PHA/mg-TSS) in SBR1, SBR2, SBR3, and SBR4, respectively. Uncoupled carbon and nitrogen feeding regime (SBR3) showed the best PHA accumulating ability when acetate was used as feed. Also, the SBR3 was fed by soft-drink industrial wastewater to evaluate the capability of the selected strategy for treating real wastewater, which 13.75% of mg-PHA/mg-TSS was achieved.