By Danny Dehon

Monique Magee Melissa Wason Shreya Purohit

Over view

• Introduction• Objective• Criteria• General flow chart• Design• Detailed flow chart• Cost analysis• References

IntroductionWhat 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?Why do we need to treat waste water?

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.

Criteria

GENERAL FLOWCHART

Pre-treatment

General Design Considerations

Main sewer linediameter=14 inches

flow 1MGD= 1.54 ft 3/svelocity 1.3ft/s

Q=VAmade of stainless steel

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

CalculationBernoulli’s equation

Wg

Vph

2

211

1 g

Vph

2

222

2

e

WQP

Where h2= 70 ft, V2= .8ft/s, and V1= 1.1ft/s

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

Pre - treatmentProcess

stepRetention

timedimensions velocity power skimmers other

Aerated grit tank

3 minutes 4.4*8.82 ft Opening .5*.25 inches

Skimming tank

10 minutes H: d6.15: 24.6 , ratio 4: 1

8.69ft* .5”, sticks down 4inches

Volume = 928.4 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

Pre Treatment CalculationsAerated grit removal chamberVolume

Skimming tankVolume

Tank dimensionsVolume = 4x3

352.27832.2083344.694 ftgalQtV D

34.92844.69441044.694 ftgalQtV D

ftV

x 15.64

4.928

4

3

1

3

1

Primary Sedimentation Tanks

Retention time• 90 minWater velocity.665ft/sDimensions• width 15.8 ft• length 52.77 ft• Depth 10 ft.

Calculations

• Water velocity

• Dimensions

s

ftVV Ts 665.

2

31.1

2

ftV

x

xxxHWLV

77.523

56.8355

3

3)10)(3)(.(

2

1

3

1

2

Trickling Filters

Tipping tray•Retention time: 5 minute•Dimensions: h=r =7.04ftFilter•Dosing cycle : 5 min•Retention time: 25 min•Dimensions h=r=13.04ft•Drainage = 5o slope•ventilation

Calculations.• Volume • R=h=x

ftV

x 04.72.46433 3

1

3

1

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 wasteScraper:• mechanically operated • 5 arms. • Scrape off material from the bottom

Calculation• Water velocity

• Dimensions

• R=2h

s

ftVV TW 44.)31.1(

3

1

3

1

ftV

x 29.54

79.1856

4

3

1

3

1

Chlorination- disinfect water

Calculations

• Retention time

• = 68 minutesgal

lbt

gal

lb min7.1025.

De –chlorination chamber

• Remove residual chlorine using SO2- above standards .0058 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

Calculations • Basic chemistry

• X = 0.012 2

2

2

2

011.000833.0

00917.0

lbCl

xlbSO

lbCl

lbSO

Cost analysisStep Initial cost Daily cost

pumping 2500 950.4

pipes 300 0

Bar screens 8300 432.00

Aerated grit chamber 6500 648

Skimming tank 25000 0

Aeration tank 45000 756

Trickling filters 35000 918

Secondary sedimentation tank 10,000 810

chlorination 665000 233.03

De-chlorination 23,500 233.8

TOTAL COST

INITIAL• $236,100

DAILY • $4981.23

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.•