Effect of inoculum and organic loading on mixed culture polyhydroxyalkanoate production using crude glycerol as the substrate.

Two different sources of activated sludge were inoculated to select and enrich polyhydroxyalkanoate (PHA) producing culture from crude glycerol. The results showed that the sludge taken from the wastewater treatment plant with higher microbial diversity could enrich PHA producing culture with higher PHA synthesis capacity (25.93%) and specific PHA storage rate (0.27 mg COD/(mg·h)) in a short enrichment time, comparing to the sludge taken from the enriched PHA-producing culture using VFAs as the substrate. The enrichment performance under different organic loadings were investigated and similar microbial community composition, good operating stability and high PHA accumulation (SBR#1, 36.59%; SBR#2, 36.33%) was observed at 2000 mg COD/(L·d) when crude glycerol was used as the substrate. The maximum content of PHA was affected by the concentration of glycerol. Gardnerella was for the first time found to be the dominant genus in the PHA production system using crude glycerol. The research would guide the application of using crude glycerol resources for PHA production.