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Biological Sludge Reduction in MBBR Process

Tahmasebian Dehkordi, Sepehr | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45325 (06)
  4. University: Sharif University of Technology
  5. Department: Petroleum and Chemical Engineering
  6. Advisor(s): Borghei, Mehdi; Moslehi Moslehabadi, Parivash
  7. Abstract:
  8. Laboratory experiments were carried out to investigate the effect of ultrasound waves on sludge reduction in MBBR bioreactor for industrial wastewater. The experiments were performed using two identical 20L MBBR bioreactor under same operational conditions. In MBBR with return sludge, sludge was collected from clarifier and after being sonicated, returned to the system by pump.
    For determining optimum intensity and time duration of ultrasound, 0.3lit of MBBR sludge was sonicated with intensities of 20, 30, 60, 120, 150, 250 w/cm2 and time duration of 5, 10, 15, 20, 30 min. Afterward, these two parameters were optimized with Energy Efficiency Index. As the results shown, intensity of 120 and 150 w/cm2 and time duration of 15 min was regarded as best.
    Experiments were carried out with optimum intensities in two 30 days periods. Compared with blank reactor, Chemical Oxygen Demand (COD) removal percentage and yield with intensities of 120 and 150 w/cm2 were reduced from 94.92% to 91.96% and 83.63% and from 0.247 to 0.125 and 0.073, respectively. With changing ultrasonic intensity, particle size distribution and settling velocity have altered in such a way that with increasing ultrasonic intensity from 120 w/cm2 to 250 w/cm2, mentioned parameters were reduced from 29.29 μm to 27.1 μm and 22.67 μm and from 9.57 to 8.31 and 5.23 m/hr, respectively. Sludge reduction with 120 w/cm2 was calculated 42% and with 250 w/cm2 was 79%. As results shown, applying ultrasonic with intensity of 120 w/cm2 and time duration of 15 min was regarded as optimum in MBBR systems. Also, applying too high and too low powers for sludge reduction in these bioreactors is not suggested
  9. Keywords:
  10. Sludge Reduction ; Moving Bed Biofilm Reactor (MBBR) ; Ultrasonic Waves ; Sludge Disintegration

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