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Biologically derived polyesters known as polyhydroxyalkanoates (PHAs) represent a potentially ''sustainable'' replacement to fossilfuel-based thermoplastics. However, current commercial practices that produce PHA with pure microbial cultures grown on renewable, but refined, feedstocks (i.e., glucose) under sterile conditions do not represent a sustainable commodity. Here, we report on PHA production with a mixed microbial consortium indigenous to an activated sludge process on carbon present in municipal wastewaters. Reactors operated under anaerobic/aerobic and aerobic-only mode and fed primary solids fermenter liquor maintained a mixed microbial consortium capable of synthesizing PHA at 10 to 25% (w/w), while reducing soluble COD by approximately 62 to 71%. More critically, an aerobic batch reactor seeded from the anaerobic/aerobic reactor and fed fermenter liquor achieved approximately 53% PHA (w/w). Results presented suggest that environmentally benign production of biodegradable polymers is feasible. We further used PHA-rich biomass to produce a natural fiber-reinforced thermoplastic composite that can be used to offset advanced wastewater treatment costs. Water Environ. Res., 79, 2396Res., 79, (2007.

The bioplastic poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), was isolated from a bioreactor using mixed microbial consortia fed volatile fatty acids (VFA), from fermented dairy manure, as the carbon source. The molar fraction of 3-hydroxyvalerate (3HV) amounted to 0.33 mol mol 21 for two isolated PHBV samples as determined by GC-MS and 1 H-NMR spectroscopy. The chemical, thermal, and mechanical properties were determined. The PHBVs had relatively high M w (790,000 g mol 21 ). Only a single glass transition temperature (T g ) and melting point (T m ) were observed. Isolated PHBVs exhibited good flexibility and elongation to break as compared with commercial PHBVs with lower HV. The diad and triad sequence distributions of the monomeric units were determined by 13 C-NMR spectroscopy and followed Bernoullian statistics suggesting that the PHBVs were random. The PHBV sequence distribution was also characterized by electrospray ionization-mass spectrometry (ESI-MS n ) after partial alkaline hydrolysis to oligomers showing a random 3HV distribution.