Production of PHA by Mixed Culture from Sequencing Batch Reactor (SBR) with Substrates of Acetate and Glucose

Abstract

To study the production of polyhydroxylakanoate PHA by excess activated sludge which is the waste from wastewater treatment plant, parameters effecting to the production that are types of organic substrate and type of activated sludge itself were investigated. Two anaerobic—aerobic sequencing batch reactors, each volume of 10 liters, labeled as ASBR and GSBR were operated with the same COLD concentration of 1500 mg/l hut different type of carbon source. ASBR was fed with acetate and COD/P ratio of 42/1 while the other with glucose and COD/P ratio of 100/1. The sludge from steady operated SBRs were conducted in batch experiments under anaerobic condition for 24 hours. Four types of organic substrates used in batch experiments were acetate, glucose, glucose to acetate (2:1) and glucose to acetate (1:2) with the COD of 1,500 mg/l in all.

The results in the batch experiments showed that ASBR sludge, acclimated with acetate and fed with phosphorus enough for the proliferation of polyphosphate accumulated organisms PAOs, synthesized more PHA than GSBR sludge in all substrates used. PHA accumulated in ASBR sludges were 19.8 14.9 12.8 and 8.9 percent by weight for acetate, glucose to acetate (1:2), glucose to acetate (2:1) and glucose, respectively. Same amount of PHA around 5.2—5.9 percent by weight were synthesized in GSBR sludges. Furthermore, the PHA composition like polyhydroxybutyrate (PHB) and polyhydroxyvalerate (PHV) depended on the ratio of acetate to glucose in the substrate, higher acetate, more PHB composition in PHA production.

Keywords : Acetate / Glucose / Production of Polyhydroxyalkanoae / Polyhydroxybutyrate / Polyrhydroxyvalerate / Polyphosphate Accumulating Organisms