Water and Wastewater Engineering

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16-38 WATER AND WASTEWATER ENGINEERING

Acid

dosing

stem

Scale inhibitor

dosing system

Cartridge filters

RO feed pumps

RO system

Air

RO concentrate

to disposal

Hypochlorite

generation and

dosing system

Sodium hydroxide

dosing system

Product water to clearwell

Ion-exchange

system

Brine to disposal

Feedwater

from wells

51,000 m

19,000 m

32,000 m

18,600 m

9,800 m

25,400 m

53,800 m

Feedwater

from wells

9,800 m

Air

FIGURE P-16-3

Chino I WTP.

MWW established the following criteria for evaluation of alternatives to upgrading

the plant:

• C o mpliance with current and future regulations.

• Reliability to produce a high-quality water free of taste and odor and

Cryptosporidium.

• Compatibility with future regulatory changes and technological developments with

particular emphasis on Cryptosporidi

um.

• Increased use of technology to compensate for reduced staffing levels.

• Costs that were commensurate with the levels of reliability of the alternative.

The process flow diagram for the existing process is shown in Figure P-16-4.

As part of the initial screening process, develop a short list (six or less) of process

alternatives to be

considered.

DRINKING WATER PLANT PROCESS SELECTION AND INTEGRATION 16-39

16-5. In Case Study 16-2, DAF was selected for dewatering in the residuals treatment

train. Suggest two other appropriate alternatives that might appear on a preliminary

screening list.

16-6. Propose a screening list of treatment options for a community supply, including treat-

ment trains for the following surface water quality characteristics. Ass

ume a popula-

tion of 10,000.

Mississippi

River

Softening

Recarbonation Reservoir

ReservoirRapid sand

filter

Mix/coagulation/

flocculation/setting

To distribution

, NH

Lime &

KMnO

PAC

FIGURE P-16-4

MWW WTP.

Parameter

Value,

mg/L as CaCO

Calcium 111

Magnesium56

Sodium 63

Potassium5

Bicarbonate 110

Sulfate 100

Chloride15

Nitrate 10

Phosphate 1

pH 7.0

Temperature 4–26C

TOC 10 mg/L

Turbidity 7 NTU

16-40 WATER AND WASTEWATER ENGINEERING

16-7. Propose a screening list of treatment options for a community supply including treatment

trains for the following well water quality characteristics. Assume a population of 35,000.

Parameter

Value,

mg/L as CaCO

Calcium 153

Magnesium 115

Sodium 438

Potassium32

Bicarbonate 460

Carbonate 20

Sulfate 15

Chloride239

Nitrate 1.8

Fluoride 0.4

Carbon dioxide 22.6

Iron 0.15 mg/L

Manganese 0.20 mg/L

pH 7.8

Temperature 5–12C

TOC 7.2 mg/L

Turbidity 1.5 NTU

16-8. Propose a screening list of treatment options for a community supply including treat-

ment trains for the following well water quality characteristics. Assume a population

of 3,000.

Parameter

Value,

mg/L as CaCO

Calcium318

Magnesium51

Sodium 198

Potassium 12

Bicarbonate 200

Sulfate 151

Chloride239

Nitrate 29

Fluoride 1.0

Carbon dioxide 2.0

Iron 0.13 mg/L

Manganese 0.01 mg/L

pH 7.5–8.3

Temperature 4–8C

TOC 1.0 mg/L

Turbidity 1.0 NTU

DRINKING WATER PLANT PROCESS SELECTION AND INTEGRATION 16-41

16-9. The city of Des Moines obtains its water from three sources: the Des Moines River,

the Raccoon River, and an infiltration gallery. The source water is seasonally high in

nitrate as shown in Figure P-16-9.

Raccoon

20.0

18.0

16.0

14.0

12.0

10.0

8.0

6.0

4.0

2.0

0.0

mg/L as N

1/1/2006

2/1/2006

3/1/2006

4/1/2006

5/1/2006

6/1/2006

7/1/2006

8/1/2006

9/1/2006

10/1/2006

11/1/2006

12/1/2006

2006 Source water nitrate

Nitrate levels in water from the infiltration gallery are much less than those

found in the rivers.

Des Moines

Infiltration Gallery

FIGURE P-16-9

Des Moines source waters.

( Source: Jones, Hill, and Brand.)

S uggest a treatment scheme, including a new ion exchange treatment proc ess, and

operational plan to keep the treated water nitrate concentration less than 10 mg/L as

N while minimizing treatment costs. Assume that the ion exchange facility operat-

ing and amortization costs are three times that of the other facilities. The average

demand is 113,000 m

/ d. Use the following “worst case” production and nitrate

assumptions:

Source

max

Nitrate,

mg/L as N

Des Moines River 2.2 14.0

Infiltration gallery 1.0 12.0

Raccoon River 1.0 18.0

Ion exchange 0.4 0.0

16-10. Flint’s proposed process flow diagram is shown in Figure P-16-10. Identify the items

missing from Kawamura’s list and mark where they should be on a copy of the pro-

cess flow diagram.

16-42

Ozone

Finished water pumpingFinished water reservoirUV disinfection

Dual media filtration

with air/water backwash

Recarbonation

Softening basin

Chlorine

Plate settlers

Three-stage

flocculation

Rapid

mix

Flowmeter

Ozonation

Calcium oxide

Fluoride

Raw water

pumping

Carbon

dioxide

Raw water

screens

City of Flint

Sodium

bisulfate

Ferric chloride

Coagulant aid polymer

Floculation aid polymer

Polymer

Soda ash

Anhydrous ammonia

Proposed water treatment

plant process schematic

Flow

meter

FIGURE P-16-10

Flint’s WTP.

DRINKING WATER PLANT PROCESS SELECTION AND INTEGRATION 16-43

16-11. Thornton’s process flow diagram is shown in Figure P-16-11. Identify the items

missing from Kawamura’s list and mark where they should be on a copy of the pro-

cess flow diagram.

East gravel

lakes (EGL)

EGL pump

station

(3.5 m

/s capacity)

WGL pump

station

(1.3 m

/s capacity)

Supernatant

Raw water

splitter

Ultrafiltration

membranes

Primary

recovery

trains

Secondary

recovery trains

Reject tank

CIP recirculation line

Secondary recovery

pass line

Recirculation

pump

CIP line

Back-pulse line

Overflow

CIP pump

Sump pump

UV disinfection

Ultrafiltration

permeate

Clearwell

High–service

pump station

To distribution

system

CIP tank

Back-pulse

pump

Back-pulse

tank

Drain

Reject pump

Blower

Clarifier

flow balancing

Upflow solids

contact clarifier

Sludge blow-down

1.8 m distribution

channel

Sludge

pump

Lagoons

West gravel

lakes (WGL)

FIGURE P-16-11

Thorton’s WTP.

16-12. Erie County Water Authority’s Sturgeon Point Plant residuals handling process flow

diagram is shown in Figure P-16-12. Identify the items missing from Kawamura’s

list and mark where they should be on a copy of the process flow diagram.

16-13. Des Moines residuals handling proc

ess flow diagram is shown in Figure P-16-13.

Identify the missing items and mark where they should be on a copy of the process

flow diagram.

16-14. Estimate the headloss in Stillwater’s launder orifices (Example 16-1) assuming that

the orifices become encrusted and are act

ually only 4.0 cm in diameter.

16-15. Design the orifice for Sweetwater’s upflow clarifier weirs. The flow rate is 7,400 m

/ d.

There are eight radial weirs. The center column of the upflow clarifier is 1.3 m in

diameter. The tank is 12.0 m in diameter. Assume the orifices are 5.0 cm in diameter.

16-44 WATER AND WASTEWATER ENGINEERING

FIGURE P-16-12

Sturgeon Point WTP residuals handling.

( Source: Davis and Cornwell, 2008.)

Alum

sludge

Distribution

box

Polymer

Pumps

Equalization

tank

Filtrate

weir

Filtrate

disposal

To disposal

Pumps

Precoat

Conditioned

sludge

retention

tank

Sludge cake

removal

Sludge

thickener

Reaction

mixer

tank

Lime

To disposal

Pressure filter

Sludge

thickener

Sludge

decant

tank

16-16. Determine the cross-sectional dimensions of the launders for Stillwater’s upflow

clarifier (Problem 16-15).

16-17. Determine the cross-sectional dimensions for the launders for a rectangular settling

basin with a flow rate of 12,500 m

/ d. There are three launders in the tank.

16-18. Estimate the elevations to plot the hydraulic grade line for a small coagulation plant

given the dimensions and headloss data shown below. The ground surface slopes

from an elevation of 485.0 m to an elevation of 481.0 m above mean sea level. The

top of the clearwell storage tank is 2.00 m below the ground surface. The weir con-

trolling the water level in the clearwell i

s set 2.00 m below the top of the tank.

Tank

Overall

height, m

Water

depth, m

Profile

length, m

Headloss,

Upflow solids contact 5.90 5.3015.0 0.14

Recarbonation 5.18 4.57 24.0 0.14

Rapid sand filter 3.39

2.39

4.90 2.39

Tank profile dimensions and headloss data

Water depth is measured from the filter floor, that is, the bottom of the drainage blocks.

DRINKING WATER PLANT PROCESS SELECTION AND INTEGRATION 16-45

FIGURE P-16-13

Des Moines WTP residuals handling. Supernatant from storage is recycled to head

end of plant.

Filtrate

Press

Recycle

Filtrate

Pump

bypass

oon River

Des Moines

River

West

low

lift

Presedimentation

sludge vault

Presedimentation

basin

Presedimentation

basin

Lagoon system

Sludge line

Emergency route

380 m

Storage

Press

Pump

bypass

Recycle

Recycle liquids

to storage

Key

and

Recharge ponds

Gallery system

Softening

basin

Softening

basin

Softening

basin

Softening

basin

Dewater

vault

Dewater

vault

Filtration

Sludge

vault

Shared primary

secondary

pumping

in series

Redundant pump

Junction

chamber

3,000 m

storage

Uniformity

delumping &

conveying

Land

application

Stock piling

all-weather site

Unload at field

location

Trailers

Contracted

distribution

Scale system

Sludge line

16-46 WATER AND WASTEWATER ENGINEERING

Prepare a sketch drawing showing the hydraulic profile for the waster treatment plant

with the vertical dimensions and headlosses.

16-19. Locate the water treatment plant on the topographic map shown in Figure P-16-19

and estimate the elevations used to plot the hydraulic grade line for a small softening

plant given the dimensions and headloss data s

hown below. Prepare a sketch show-

ing the hydraulic profile for the waster treatment plant with the vertical dimensions

and elevations. The 100 year flood elevation is 804 m. Water is to be pumped from

the bottom of the filters to an elevated storage tank.

Tank

Overall

height, m

Water

depth, m

Profile

length, m

Headloss,

Flash mix 3.00 2.20 1.0 0.05

Flocculation 7.50 6.87 25.0 0.45

Settling 3.502.50 33.5 0.14

Rapid sand filter 4.30

3.00

9.753.00

Tank profile dimensions and headloss data

Water depth is measured from the filter floor, that is, the bottom of the drainage blocks.

FIGURE P-16-19

Topographic map.



 =



300

 =

806

804

802

100

800

802

804

806

808

810

812

DRINKING WATER PLANT PROCESS SELECTION AND INTEGRATION 16-47

16-7 DISCUSSION QUESTIONS

16-1. In the Chino WTP processes (Problems 16-2 and 16-3), there is a cartridge filter

upstream of the RO feed pump. Explain its purpose and why it is placed where it is.

16-2. The mayor has asked you to explain to the city council members how a SCADA

system can save money. Prepare a written ex

planation with examples.

16-3. Match the following processes with the appropriate control algorithm.

a. Hypochlorite chlorinator ( ) Feed-forward

b. pH ( ) Compound

c. Alum feed ( ) Feed-forward plus feed-back with nonlinear algorithm

16-4. Explain why a PLC for a pump should have HOA capability.

16-5. What security access zone and access control should be recommended for the

SCADA system

16-8 REFERENCES

AWWA (1993) Instrumentation and Computer Integration of Water Utility Operations, American Water

Works Association, Denver, Colorado.

AWWA (2001) Instrumentation and Control, Manual M2, American Water Works Association, Denver,

Colorado.

Barthuly, P. J. (2005) “Hydraulics,” in E. E. Baruth (ed.), Water Treatment Plant Design, American

Water Works Association and American Society of Civil Engineers, McGraw-Hill, New York,

p. 16.1–16.15.

Booth, R., A. Bowm

an, F. Gist, J. R. Ringold (2004) “Security Hardware and Surveillance Systems for

Water Supply Systems,” in L. W. Mays (ed.), Water Supply Systems Security, McGraw-Hill, New

York, pp. 12.1–12.37.

Christianson, M. and D. Origer (2007) “Going Wireless with SCADA Technology,” Opflow, vol. 33,

no. 7, pp. 10–12.

Corbin, D. J. (2005) “Site Selection and Plant Arrangement,” in E. E. Baruth (ed.), Water Treatment

Plant Design, American Water Works Association and American Society of Civil Engineers,

McGraw-Hill, New York, p. 23.1–23.37.

Davis, M. L. and D. A. Cornwell (2008) Introduction to Environmental Engineering, McGraw-Hill,

New York, p. 323.

Fischer, P., M. Lichwardt, J. Dye, and B. Hart (2006) “Quenching Thornton’s Thirst,” Civil Engineering,

vol. 76, no. 12, pp. 60–65.

Jones, C. S., D. Hill, and G. Brand (2007) “Use a Multifaceted Approach to Manage High Source-Water

Nitrate,” Opflow, vol. 33, no. 6, pp. 20–22.

Kawamura, S. (2000) Integrated Design and Operation of Water Treatment Facilities, 2nd ed., John

Wiley & Sons, New York, pp. 65–72, 330–331.

Kubel, D. (2005) “Process Instrumentation and Controls,” in E. E. Baruth (ed.), Water Treatment Plant

Design, A merican Water Works Association and American Society of Civil Engineers, McGraw-Hill,

New York, p. 20.1–20.42.

Logsdon, G., A. Hess, and M. Horsley (1999) “Guide to Selection of Water Treatment Processes,” in

R. D. Letterman (ed.), Water Quality and Treatment, 5th ed., American Water Works Association,

McGraw-Hill, New York, pp. 3.1–3.26.

Mays, L. W. (2004a) Water Supply Systems Security, McGraw-Hill, New York.