Streamline - Spring 2015 - (Page 37)

Wastewater Math QUESTIONS Answers on page 46 1 What is the volume in gallons of a rectangular tank that has a length of 50 ft, a width of 20 ft and a height of 144 inches? a. 144,000 gallons c. 89,760 gallons b. 1,077,120 gallons d. 1,604 gallons 8 What is the capacity (gallons) of a 10 inch pipe that has a length of 1,000 feet (assume that the pipe is full)? a. 4045 gallons c. 74800 gallons b. 7850 galloons d. 540 gallons 9 The flow velocity in a 12 inch sewer main is 8 ft/sec. What is the flow rate in ft3/sec? a. 718 ft3/sec c. 904 ft3/sec b. 6.3 ft3/sec d. 301 ft3/sec Determine the blower capacity in ft3/min of a digester that is 15 ft long, 12 ft wide and 22 ft deep? Hint: blower capacity, ft3/min = vol, ft3/20 a. 6600 ft3/min c. 400 ft3/min b. 330 ft3/min d. 198 ft3/min 3 10 2 A wastewater treatment plant has two (2) primary clarifiers that are 32 ft in diameter and 20 ft deep. Find the detention time in hours for each clarifier when the plant flow is 2.6 MGD? a. 2.2 hrs c. .05 hrs b. 130 hrs d. 1.6 hrs Calculate the reduction in volatile matter when the raw sludge entering the digester has a volatile content of 72% and the volatile content of the digested sludge is 36%? a. 50.2% c. 24.3 % b. 36 % d. 40 % 4 What is the hydraulic loading rate (gpd/ft2) of a trickling filter with a 75 ft diameter that is receiving a flow of 2,500 gpm? a. 187500 gpd/ft2 c. 815 gpd/ft2 2 b. 33 gpd/ft d. 640 gpd/ft2 5 The MLSS concentration in an aeration basin is 2,300 mg/L. The volume of sludge after 30 minutes is 475 ml/L. What is the sludge volume index (SVI), mL/g? a. 206 mL/g c. 1000 mL/g b. 145 mL/g d. 475 mL/g 6 Determine the sludge volume reduction of 5000 gallons with an initial 2% solid concentration increased to a 5% concentration? Hint; how many gallons are removed by the thickening process? a. 250 gallons c. 150 gallons b. 100 gallons 7 Calculate the geometric mean of the following Ecoli counts; 10, 1, 120, 640 and 1800? a. 67.3 c. 120 b. 466.2 d. 640 730306_UV.indd 1 w w w . v r w a .04/02/15 37 AM o r g 3:49

Table of Contents for the Digital Edition of Streamline - Spring 2015

From the President: Power Failure
From the Executive Director: Highlights from 2014
The Sustainability Managed Utility
Communication… Say What?
Flushing Away the Ebola Threat
Hazard Communication Standards – Guidelines for OSHA Compliance
State Water Control Board Approves Controversial Permit
VRWA Said Goodbye to Past Executive Director
USDA Rural Development
The RATES Program
Adequate Rates versus Affordability
NRWA Recap
Debt Refinancing: An Alternate Source of Capital
How the Cloud is Revolutionizing the Future of Water Utility Management
Southern Corrosion Supports Victory Junction
Throwing My Loop: Call Me Anytime
Wastewater Math
Booster Club
eLearning Benefits
Membership Application
Do You Know What Your VRWA Benefits Are?
VRWA Mailbag
New Members
Board of Directors
VRWA Committees
Index to Advertisers/

Streamline - Spring 2015