A primary wastewater treatment uses centrifugation for dewatering of primary sedimentation sludge. The raw wastewater contains 300 mg/L TSS and 250 mg/L BOD5. The average daily flow to the treatment plant is 5000 m3/d. In primary sedimentation basin, TSS removal is 55%, and BOD5 removal is 30% of the incoming flow.  The primary sludge contains 3.5 % solids. The TSS and BOD5 capture efficiency of centrifugation is 90 % each, and the moisture (water) content of the sludge cake is 70 %.  Assume the specific gravities of the primary and sludge cake are 1.01 and 1.06 g/cm3. 1. Calculate the primary sludge flowrate (underflow rate) (m3/d). 2. Calculate sludge cake flowrate (m3/d).

Question
  • A primary wastewater treatment uses centrifugation for dewatering of primary sedimentation sludge. The raw wastewater contains 300 mg/L TSS and 250 mg/L BOD5. The average daily flow to the treatment plant is 5000 m3/d. In primary sedimentation basin, TSS removal is 55%, and BOD5 removal is 30% of the incoming flow.  The primary sludge contains 3.5 % solids. The TSS and BOD5 capture efficiency of centrifugation is 90 % each, and the moisture (water) content of the sludge cake is 70 %.  Assume the specific gravities of the primary and sludge cake are 1.01 and 1.06 g/cm3.
  • 1. Calculate the primary sludge flowrate (underflow rate) (m3/d).
  • 2. Calculate sludge cake flowrate (m3/d).

 

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