Optimization of polyhydroxyalkanoate storage using mixed cultures and brewery wastewater

BACKGROUND Brewery wastewater is a potential feedstock for polyhydroxyalkanoates ( PHA ) production since it contains high concentrations of easily biodegradable organic matter. Activated sludge was submitted to aerobic dynamic feeding conditions in a sequencing batch reactor fed fermented brewery wastewater in order to select a microbial culture with high storage capacity. The effect of several operational parameters, such as substrate concentration (57, 79 and 109 Cmmol L −1 ), pH (7 and 9 and without pH control (8–9)) and temperature (15 and 30 °C and without T control (15–28 °C)) was investigated. RESULTS The concentration of PHA stored by the activated sludge increased with the substrate concentration, with 39% PHA content on a dry biomass basis obtained at 109 Cmmol L −1 . The storage yield increased from 0.35 to 0.43 Cmmol HA Cmmol −1 VFA when the substrate concentration was raised from 57 to 79 Cmmol L −1 . However, a further increase in substrate concentration to 109 Cmmol L −1 led to a storage yield decrease to 0.39 Cmmol HA Cmmol −1 VFA . Control of pH and temperature did not enhance PHA storage. CONCLUSIONS Brewery wastewater is a good feedstock for production of PHAs using mixed cultures enriched under feast and famine conditions. PHA production can be enhanced by manipulating the operational conditions. © 2016 Society of Chemical Industry