Page 27 - Simplified Wastewater Treatment Fundementals\Package Plants

Package Plants

Package Plant Math

Volume and Gallons Capacity of a Rectangle

A rectangular aerobic digester that is 30 feet long, 15 feet wide and 10 feet

deep is fed with waste activated sludge at a rate of 300 gallons per day. The

aerobic digester tank has 2 feet of sidewall depth left until its full. How many

days does the Operator have until the digester is full? In this example, do not

consider the additional volume removed by decanting.

Formula Needed

Length x Width x Depth x 7.48 gallons/cubic feet = Gallons

30 x 15 x 10 x 7.48 gal/cubic ft = 33,600 gallons

33,600 gallons ÷ 10 feet of depth = 3,600 gallons per foot

2 feet of sidewall depth remaining = 3,600 x 2 (or 7,200 gallons)

7,200 gallons ÷300 gallons/day = 24 days until full