If you look at the specifications, they read as follows:
A. Wastewater flow rates (e.g., municipal, industrial, commercial)
B. Unit operations and processes
C. Primary treatment (e.g., bar screens, clarification)
D. Secondary clarification
E. Chemical treatment
F. Collection systems (e.g., lift stations, sewer network,
infiltration, inflow)
G. National Pollutant Discharge Elimination System
(NPDES) permitting
H. Effluent limits
I. Biological treatment
J. Physical treatment
K. Solids handling (e.g., thickening, drying processes)
L. Digesters
M. Disinfection
N. Nitrification and/or denitrification
O. Operations (e.g., odor control, corrosion control, compliance)
P. Advanced treatment (e.g., nutrient removal, filtration, wetlands)
Q. Beneficial reuse (e.g., liquids, biosolids, gas)
When I took the exam, the one difficulty I ran into with these problems was process flow as it related to generation of sludge, Waste Activated Sludge (WAS), and some of the common parameters/measurements utilized in the design problems like Mixed Liquid Volatile Suspended Solids (MLVSS) and F:M ratio. From the Metcalf and Eddy book, I would focus on solving problems and makign sure you understand common parameters, conversions, and how these parameters are applied.
JR