8833-3 - Mississippi State University Department of Civil...

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Mississippi State University Department of Civil Engineering CE 8833: Sludge Treatment and Disposal Spring 1996 Exam 3 Truax Name:_________________________________________________ (30%) 1. A 250,000 gallon aerobic digester is operating at 55 o F and a reactor solids concentration of 23,000 mg/l. The influent flow rate is 20,000 gpd and contains 10,000 mg/l of solids having a volatile-to-total solids ratio of 0.75. The thickener used to concentrate the recycled sludge achieves a 35,000 mg/l solids concentration with a sidestream solids concentration of 250 mg/l (55% volatile). A 45 percent volatile solids destruction is desired. Using the attached figures, estimate: a) the sludge age (days), b) oxygen requirement (lb/day), c) sludge recycle rate (gpd), d) sludge wasting rate (lb/day), and e) sludge wasting rate (gpd), and f) sidestream flow rate (gpd). (30%) 2. A stabilized sludge is produced at a rate of 450 pound of volatile solids per day. The total solid concentration of the sludge is 2.3 percent and has a volatile-to-total solids ratio of 0.44.
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This note was uploaded on 06/12/2011 for the course CE 8833 taught by Professor Truax during the Spring '11 term at Mississippi State.

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