Simultaneous COD Removal and PHA Production in an Activated Sludge System under Different Temperatures


  • Sopa Chinwetkitvanich Mahidol University
  • Clifford W. Randall Virginia Polytechnic Institute and State University
  • Thongchai Panswad Chulalongkorn University



Activated sludge, polyhydroxyalkanoate, nutrient limitation, biodegradable plastics, temperature effects.


The purpose of this study was to investigate PHA production by activated sludge biomass under different temperatures. The two-step approach, i.e. utilizing a growth phase followed by a nutrient(s) limitation phase, was applied to stimulate PHA accumulation. Each of three intended temperatures, 10oC, 20oC and 30oC, was investigated with combined N&P limitation. Four liter (L) fully aerobic SBRs were used for all experiments, and operated with a 6 h cycle time, a 10 h HRT and a 10 day SRT. The maximum PHA cellular contents and total concentrations achieved during the N&P limitation periods in the 10 and 20oC systems were very similar, i.e. 45 and 43% of the TSS and 2133 and 2239 mg/l, respectively, whereas the 30oC results were lower at 33% of TSS and 1476 mg/l. The biomass temperature clearly had a strong inverse effect upon PHA productivity. It decreased from 427 and 204 to 148 mg/l-day as reactor temperature increased from 10 to 20 and 30oC, respectively. As well, the PHA yields decreased from 0.38 to 0.16 and 0.11 mg PHA/mg CODu, respectively. The results strongly indicate that activated sludge PHA accumulation stimulated by combined N and P limitation is inversely correlated with temperature.


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Author Biographies

Sopa Chinwetkitvanich

Department of Sanitary Engineering, Mahidol University, 420/1 Rajvithee Rd., Rajthevee, Bangkok 10400, Thailand

Clifford W. Randall

Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA

Thongchai Panswad

Department of Environmental Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand


Published In
Vol 13 No 3, Aug 6, 2009
How to Cite
S. Chinwetkitvanich, C. W. Randall, and T. Panswad, “Simultaneous COD Removal and PHA Production in an Activated Sludge System under Different Temperatures”, Eng. J., vol. 13, no. 3, pp. 1-12, Aug. 2009.