1992 Volume 28 Pages 39-49
Polyphosphate rich anaerobic aerobic activated sludges were fed with acetate and/or propionate under anaerobic condition to produce polyhydroxyalkanoate (PHA), a biodegradable plastic. All the carbon sources anaerobically uptaken by the sludges were converted into PHA, and the maximum PHA accumulation in the sludges was 12% of the mixed liquor suspended solid. The amount and the composition of the accumulated PHA were affected by the composition of the carbon sources for the PHA production and that for the sludge acclimatization. All the sludges used in the present research produced 3-hydroxybutyrate rich PHA from acetate. Sludges acclimatized with substrates containing acetate and propionate produced PHA composed mainly of the same amounts of 3-hydroxyvalerate and 3-hydroxy-2-methylvalerate from propionate. But a sludge acclimatized with a substrate without propionate held little ability to produce 3-hydroxy-2-methylvalerate, and took up less propionate than the other sludges. All the sludges metabolized intracellular carbohydrates simultaneously with the anaerobic uptake of acetate and/or propionate, and converted not only the carbon sources but also the intracellular carbohydrates into PHA, except for a sludge acclimatized with a substrate containing lactate. The sludge had accumulated less carbohydrates, and converted less carbohydrates into PHA than the other sludges did.
