CE 442 Final Exam with Questions and Answers

CE 442 Final Exam with Questions and Answers Why is BOD/COS information needed for wastewater quality but not for drinking water? ANSWER Waste water has a high organic matter content therefore BOD/COD information is needed for removing organic solids from wastewater. Drinking water does not have as much organic matter therefore it is not needed information What is the purpose of bar screens/ grit removal? ANSWER Bar screens/ grit will remove the large debris/ solids from the influential wastewater What type of Settling would you expect in designing a primary clarifier of a wastewater treatment plant? How would you design primary clarifier? ANSWER Primary settling of wastewaters is usually Type II settling To design the primary clarifier a batch settling test must be conducted for the design of sedimentation tank. Settling diagram for Type II Settling will be developed from batch settling test. The design detention time and surface overflow rate will be determined for the required effluent solids Advantages/ disadvantages of CSTR I'm activated sludge process: ANSWER Advantages: (i) maximum maximum equalization in oxygen uptake rate (II) relatively uniform environmental conditions for the biomass (iii) instant dilution of shock loads (iv) flexability Disadvantages: