6. Elaboration Question 4

Course subject(s) 6. Digestion of sludge and sewage

Question 4: Sludge balance

The Sludge Treatment Process utilised to treat primary and secondary sludge produced from a sewage treatment plant is depicted in the figure below.

    • Complete the following Sludge Balance illustrated in the figure below

  • a. Calculate the surface area needed for the primary sludge thickener
  • b. After dewatering the sludge is stored in a silo. Calculate the minimum volume of this silo when the sludge has to be stored for at least 4 days.
  • c. To improve the suspended solids (SS) concentration of the final product, sludge conditioning with poly electrolytes (PE) is introduced. The PE dosage is 9 kg active PE/tons. What is the daily PE (active) consumption?
  • d. With conditioning the final SS concentration is increased to 26% SS. What is the new sludge storage time in the silo?

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