1. Design of a Wastewater Treatment PlantBy
Danny Dehon
Monique Magee
Melissa Wason
Shreya Purohit

2. Over view Introduction Objective Criteria General flow chart Design
Detailed flow chart
Cost analysis
References

3. Why do we need to treat waste water?
Introduction
What is waste water?
It is a combination of liquid wastes from industries, commercial and residential areas. It also includes storm water, ground water and surface runoff
Why do we need to treat waste water?
Save aquatic life
algal boom
Depletes oxygen levels
health
can cause cholera and typhoid if consumed
reuse
drinking water
irrigation
industries

4. OBJECTIVE
To design a waste water treatment plant for a town of 10,000 people, which treats 1 million gallons of waste water per day.
The characteristics of the effluent water are in compliance with current regulatory standards.

5. Level of purification needed
Criteria
Flow rate
Concentration
Level of purification needed

6. Primary sedimentation tanks
GENERAL FLOWCHART
Main sewer line
screening
Grit tank
Skimming tanks
Aeration tanks
Primary sedimentation tanks
Trickling filters
Secondary sedimentation tanks
Chlorination
De-chlorination
Discharge
Pre-treatment

7. General Design Considerations
Collection system is separate
Topography of the area is used , built at an elevation
Gravity flow
Cuts down on cost
All tanks purchased from Pope Scientific Inc.
No tertiary treatment- secondary treatment meets town standards.

8. Incoming waste water = 1 million gallons per day
Main sewer line diameter=14 inches flow 1MGD= 1.54 ft 3/s velocity 1.3ft/s Q=VA made of stainless steel
Storm water
Sanitary wastes
Incoming waste water = 1 million gallons per day

9. Pumping of water to bar screens
Water is pumped 70 ft
880kw power needed
Vertical Turbine Solids-Handling Pumps VTSH® Series pump- specially designed to handle solids
Head:70 feet and this pump has a head of up to 110 ft
Pump Capacity: 30,000 GPM
Impeller: non-clogging, blunt, and made of cast iron,
Shaft: stainless steel

10. Calculation Bernoulli’s equation
Where h2= 70 ft, V2= .8ft/s, and V1= 1.1ft/s

11. Bar screens Removes sticks, glass, small rocks etc
Climber type bar screen
Spacing ¼ inches
Fine screening
Stainless steel to prevent corrosion
Mechanically scrapped
Solids collected in hopper and disposed

12. Pre - treatment Process step Retention time dimensions velocity power
skimmers
other
Aerated grit tank
3 minutes
4.4*8.82 ft
Opening .5*.25 inches
Skimming tank
10 minutes
H: d
6.15: 24.6 , ratio 4: 1
8.69ft* .5”, sticks down 4inches
Volume = ft3
Aeration tank
25 minutes
H: d= 1: 1
= 14.35
Velocity of fluid at tip= .75 tip vel.
Paddle = .977 rev/min
2.64 ft-lb/min
Flocculant- aluminum
Paddle- 2 feet smaller than radius
, 2ft wide

13. Pre Treatment Calculations
Aerated grit removal chamber Volume Skimming tank Tank dimensions Volume = 4x3

14. Primary Sedimentation Tanks
Retention time
90 min
Water velocity
.665ft/s
Dimensions
width 15.8 ft
length ft
Depth 10 ft.

15. Calculations
Water velocity
Dimensions

16. Trickling Filters Tipping tray Retention time: 5 minute
Dimensions: h=r =7.04ft
Filter
Dosing cycle : 5 min
Retention time: 25 min
Dimensions h=r=13.04ft
Drainage = 5o slope
ventilation

17. Calculations.
Volume
R=h=x

18. Secondary Sedimentation Tanks
Retention Time:
20 minutes
Water Velocity:
drop rest of solids out of suspension
1/3 of the velocity in the pipes, or .44 ft/s.
Dimension:
Required R: H = 2: 1,
R: H =10.57 : 5.29 ft.
Skimmer:
fence with extremely small square holes, .5 inches by .5 inches
Catches waste
Scraper:
mechanically operated
5 arms.
Scrape off material from the bottom

19. Calculation
Water velocity
Dimensions
R=2h

20. Chlorination - disinfect water
dosage
0.25lb/ gallon
Retention time
68 minutes
volume
gallons
Chlorine
residual
Water : chlorine = lb/gallon

21. Calculations
Retention time
= 68 minutes

22. De –chlorination chamber
Remove residual chlorine using SO2- above standards lb/gal
The ratio of the reaction is 2.43 x 10-6 lb sulfur dioxide for every 2.20 x 10-6 lb of chlorine.
.017 lb/ gal chlorine – neutralized with .012/gal of SO2

23. Calculations
Basic chemistry
X = 0.012

24. Secondary sedimentation tank
Cost analysis
Step
Initial cost
Daily cost
pumping
2500
950.4
pipes
300
Bar screens
8300
432.00
Aerated grit chamber
6500
648
Skimming tank
25000
Aeration tank
45000
756
Trickling filters
35000
918
Secondary sedimentation tank
10,000
810
chlorination
665000
233.03
De-chlorination
23,500
233.8

25. TOTAL COST
INITIAL
$236,100
DAILY $

26. References
Al-Layla, M. A., Ahmad, S., & Middlebrooks, E. J. (1980). Handbook of Waste Water Collection and Treatment. (G. l. culp, Ed.) Garland STPM Press.
Droste, R. L. (1997). Theory and Practice of Water and Wastewater. Hoboken: John Wiley & Sons.
Jern, W. (2006). Industrial Waste Water Treatment. New York: World Publishing Company.
Metcalf, L., & Eddy, H. P. (1935). American Sewerage Practice. New York: McGraw-Hill Book Company.
Metcalf, L., & Eddy, H. P. (1930). Sewerage and Sewage Disposal: A Textbook. New York: McGraw-Hill Book Company.
Metcalf, L., & Eddy, H. P. (1972). Wastewater Engineering. New York: McGraw-Hill Book Company.
Noyes, R. (1994). Unit Operations in Environmental Engineering. New York: William Andrew Publishing/Noyes.
Sanks, R. L. (1998). Pumping Station. London: Butterworth Heinemann.
Note: Some of the pictures are not referenced because they were taken by the authors of these papers during a visit to the Baton Rouge Wastewater Treatment Facility.