ENV4001_s11_hw3

# ENV4001_s11_hw3 - ENV 4001 ENVIRONMENTAL SYSTEMS...

This preview shows pages 1–2. Sign up to view the full content.

p. 1/3 ENV 4001: E NVIRONMENTAL S YSTEMS E NGINEERING Spring 2011 University of South Florida Homework #3 Civil & Environmental Eng. Due: Wed., Feb. 2, 2011 Prof. J.A. Cunningham Each homework assignment will be graded on a 100-point scale. For this assignment, point values of each problem are indicated. 1. (20 pts) Municipal wastewater (sewage) is usually treated by a method called “activated sludge.” We’ll learn more about that later in the semester. Below is a schematic diagram that shows the process. Plant influent Q I = 100 m 3 /hr X I = 130 mg/L Aeration basin V = 1200 m 3 X = ?? mg/L Clarifier Plant effluent Q E = 95 m 3 /hr X E = 15 mg/L Sludge recycle Q R = 30 m 3 /hr Waste sludge Q W = ?? m 3 /hr X W = 9500 mg/L The aeration basin is a completely-mixed flow reactor (CMFR) where the sewage is degraded by bacteria. It has a high concentration of suspended solids; we use the symbol X to indicate the concentration of suspended solids in the aeration basin. Because we don’t want to release a lot of suspended solids into the environment, the effluent from the aeration basin goes to a clarifier . In the clarifier, the suspended solids settle to the bottom under the influence of gravity. Therefore, the plant effluent that comes out of the top of the clarifier has a low concentration of suspended solids (denoted X E ). The sludge that comes out the bottom of the clarifier has a very high concentration of suspended solids. A fraction of the

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 06/12/2011 for the course ENV 4001 taught by Professor Staff during the Fall '08 term at University of South Florida.

### Page1 / 3

ENV4001_s11_hw3 - ENV 4001 ENVIRONMENTAL SYSTEMS...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online