Production of Polyhvdroxyalkanoates from Synthetic Wastewater Using Sequencing Batch Reactors in On-Off Sequences

Tjandra Setiadi (Department of Chemical Engineering Institut Teknologi Bandung JI. GanesaNo. 10, Bandung, INDONESIA)
Herriyanto Ronny Sondjaja (Department of Chemical Engineering Institut Teknologi Bandung JI. GanesaNo. 10, Bandung, INDONESIA)
Bambang Veriansyah (Department of Chemical Engineering Institut Teknologi Bandung JI. GanesaNo. 10, Bandung, INDONESIA)

ASEAN Journal of Chemical Engineering
Vol 4, No 1 (2004)

The biosynthesis of polyhydroxyalkanoates (PHAs) using activated sludge as cultureorganism from tapioca synthetic wastewater has been studied in a 6L sequencing batch reactor (SBR). It was found that longer aeration time caused greater chemical oxygen demand (COD) reduction but did not achieve the maximum PHA-production rate. The application of on-off sequences, however, gave an acceptable PHA- productivity rate at 0.1033 gPHA L-1 h-1 and a high storage yield of up to 0.32 gPHNg biomass, although it caused a decrease in pH and affected sludge stability. The on-off variation also produced a higher valerate copolymer content, in the range of 16.44-22.48 % for Run 1 and of 13.09-14.09 % for Run 2, compared to the customary aerated-unaerated variations. The study indicates that the use of on-off SBR sequences may be suitable for obtaining high PHA-storage yields.