Journal of Food, Agriculture and Environment

Effects of hydrodynamic turbulence on the performance of activated sludge in sequencing batch reactors

Author(s):

Qian Feng ^{1, 2*}, Jun-yi Tan ³, Li-na Chen ⁴, Hui-lian Xu ⁵

Recieved Date: 2009-12-10, Accepted Date: 2010-04-04

Abstract:

The activated sludge process (ASP) is widely adopted in treatment of domestic and industrial wastewater. ASP will be more effective if the hydrodynamic turbulence is combined. Therefore, in the present study, the effects of hydrodynamic turbulence on performance of ASP in sequencing batch reactors were investigated using cylindrical reactors in parallel. All of the activated sludge in bioreactors was incubated with a glucose-based synthetic wastewater at the same rate. Turbulent conditions were adjusted by stirring paddles in bioreactors and analyzed using the Particle Image Velocimetry (PIV) method. The characterized turbulence energy dissipation rates were used to quantify the turbulence conditions in bioreactor. The results showed that the hydrodynamic turbulence had a significant effect on the performance of activated sludge in sequencing batch reactors. The turbulence dissipation in bioreactors increased steadily as the stirring speed increased. With the steady increasing in characterized turbulence dissipation rate, the sludge volume index (SVI) decreased first and then increased, while the specific oxygen uptake rate (SOUR) and the rate coefficients for COD and NH₄⁺-N degradation rose up first and then cut down. The characterized turbulence dissipation rate was more valid in analysis compared with the usually used parameters such as the specific power input, the root-mean-square velocity gradient (G), the ratio of blade to vessel diameter (D/T_v) and superficial upflow air velocity. In conclusion, the performance of activated sludge in sequencing batch reactors could be improved in practice by adjusting the turbulence dissipation rate.

Keywords:

Activated sludge process, turbulence dissipation rate, rate coefficient, sequencing batch reactor

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Journal: Journal of Food, Agriculture and Environment
Year: 2010
Volume: 8
Issue: 2
Category: Environment
Pages: 1087-1092

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