ABSTRACT
This chapter describes of preliminary processes of screening, comminution, grit removal, and pre-aeration. Commonly used devices and applicable formulae for flow measurement in wastewater treatment plants are discussed and calculations are shown. It also includes calculation of settling velocity of grit particles and its use in sizing of grit removal units including grit channels, aerated grit chambers, and grit clarifiers.
Factors affected settling and the parameters used to operate and design clarifiers are described. It is followed by example problems. A comparison of circular clarifier and rectangular clarifier is tabulated. A brief discussion on the secondary clarifier, as it differs from the primary clarifier in design and operation, is included. The use of coagulant to enhance settling and its effects on the quality and quantity of raw sludge is discussed.
