Name Sample ExamCE 326 Principles of Environmental Engineering Water Supply and Treatment - 2" Exam

Defendable True/False Questions. If the statement is true as stated, mark it OK. If the statementis false, correct it by changin g the underlined word or words in the sentence so that it will betrue.Note atomic weights: H = 1.0, C = 12.0, 0 = 16, Fe = 55.8, Ca = 40, Al = 27, S = 32.

Noncarbonate hardness is defined as the difference between the total hardness and the• ,

ay.

LA C.The gentle mixing of colloidal particles to form larger settleable particles in a slow mixbasin is termed flocculation.

Ultraviolet light is highly effective for drinking water disinfection, but it does not leave aresidual. Consequentl y , chlorination or chloramination is also required to provide adisinfecting residual.

The effective size of a particular filter media refers to the d size. .D LL) rbv1,41

The optimum coagulant dose in a jar test is the dose where the h , c Hess is at a minimum.

7. For a given filter area and backwash flow rate an increase in depth of the sand will resultin an ii)p•ttlse in the resulting percent bed expansion.

Lk 2fb c cA.A\D"5 CC`s c-.. 1\c, 4- )

I lardness is the sum of polyvalent 4444trr5 in drinking water and has been associated witha significant decrease (about 50%) in heart disease in areas that use groundwater.

cr k. 6.0

Chlorination and bromination of surface waters with a hi g h content of • n may result inthe formation of cancer causing compounds such as THMs and DBPs.

10. GAC is used in place of anthracite in filter adsorbers to obtain removal of VOCs, SOCs,DBPs, THMs, and other adsorbable contaminants.

An example of a specified treatment technique in Safe/ Drinking Water Act, is the use offiltration for the removal of PcLyvi/i/L)..,1-i•-eride which causes gastrointestinal i llness.

0 hot r rft, r

12. The principle treatment objective for surface water is the removal of hardn ancl iron.

+kkv. \oi4-/6cAorc•Jt\/.•

Lkk. Sedimentation of alum floe typically follows Type II, or flocculant, settling, whicheI b

accurately modeled using the Stokes equation for laminar flow.

Short Answers - 8 points each

1 1. Give a brief explanation for the following:

a. What is the advantage of dual media filtration over sin g le media filtration?

b. How do slow sand filters work? St&V

c. What is the difference between Type I, II, and Ill sedimentation?vss Sys

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1 2 . For a given filter cycle indicate the appropriate item by filling in the corresponding letter:

e-I.

4.

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a. clean bed headlossh. maximum available headloss

time to backwash based on headlossheadloss, m

e. turbidity. NTU

11 time to backwash based on turbidityturbidity standard, NTU

f.l.t -r ripening

a e,1;)

s--t 1A,L e--

C, '4

13. List five inor ganic compounds that are regulated in drinkin g water and why they are aconcern.

5 Dal,

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cfco eti ak,L(crlsOLort.,4\bv

6LA- t b"

17) L

Ck,

cln\eiVl oLL

Numerical Problems :

14. (10 pts) Calculate the mixer horsepower for a rapid mix basin in a 10 mgd (milliongallons per day) water treatment plant to achieve a G value of 750 s 1 and Gt value of 45,000.

Given: G = (P/uV)°.51 hp = 745.7 watt u = 1.053X IV Pa.sC.,--t 4.g e b C.

106 ga ons = 3785 m 3I m3 = 264.2 gallons 6- -(9-.--

)

4-C-D.2., .. 3 n (

--- 0:5D ) t, 05) )i, L O N --_ (,0.5

S Os ‘, I" A. C2 \,‘,.J o k ..5

\ V.

t .., C L 0 1, 4-L "'. -4 \b X. lb

x\ 0 (.1) -2.•`t

'2., 4 2-- eic-0L

- Coal 4 L(' „ 3 v-,3

ts"5'6 c7 ))

q[-p

Cv

Temperaturez- H,CO3

pH

,3

----- 0 Xlo a/ t

L

P = 100(v,/v())10' gallons = 3785 m3

Miscellaneotts' equation s: ve = Q/A sarea of circle = nr2

Circum. = 2 ;Tr

Stokes LawP,t - d2

181.t

15. (15 pts) Calculate the bicarbonate (FICO 3 ) concentration in mg/L as CaCO, of a watersample that has the following composition:

EQUATIONS:Note the pK„, = 6.35 f r carbonic acid and bicarbonate and pIC 2 = 10.33 for bicarbonate and

carb nate at 25°C. K, = [014 -][H1 H,CO3 = CO, + H,0

x

L._

co3

(15 pts) Calculate the surface area and diameter for circular clarifiers (sedimentationbasin) for a 12 million gallon per day (1 m 3 = 264.2 gal) water treatment plant? Assumea surface overflow rate of 60 m 37m 2seland a weir loading rate of 300 m 3/m-el. Assumethat two clarifiers are used. Indicate whether inboard weirs are necessary.

K„

VS

d vR

a

vC = + + 0.34

D

24 3

R R"

5 o (Z— .:. (43 '^.^.•S

1

LA.%

n, 4S" LF2,0 0-4

1

x v-,

01.,-7 2(_'i.L Sal/

3 (,d 41-'' CJ-\

Leh L\5 •izio im4 .-._:) 2_

7,1-. 10 2 // c..\. os,v ---.4'61,-

-t\ ?-17,i(00 0:.3/ d

or '- -\-„„L,

cit r.v.,— , -2-:ii` y- ----r(' 0{ ;-_ ,..) li- c (S‘il,v....,

.Q.,....„(Th ir -

k.) .,,(2_,_. %Li I) 3 2%1 )-s

6g,lc.,

Temp = 20°C= 1.002 x 10 -3 Pa.s

v = 1.004 x 10 -6 m2/sp = 998.207 kg/m3

= 9.8 m/s2

25 deg C1.5 mg/L8.4

c)(—

k1,103 (.6.1 Co

Water Treatment Plant Design Water Treatment Plant Design Lab II & Exam II ReviewLab II & Exam II Review

CE 326 Principles of Environmental EngineeringCE 326 Principles of Environmental EngineeringTim Ellis, Ph.D., P.E.Tim Ellis, Ph.D., P.E.

Department of Civil Construction and Environmental Department of Civil Construction and Environmental EngineeringEngineeringg gg g

Iowa State UniversityIowa State UniversityMarch 25, 2009March 25, 2009

AnnouncementsAnnouncementsAnnouncementsAnnouncementsA W t Pl t Fi ld t i t dA W t Pl t Fi ld t i t d•• Ames Water Plant Field trip report due Ames Water Plant Field trip report due todaytoday

•• Design lab due next Wednesday, April Design lab due next Wednesday, April 1, 20091, 2009

•• Second Exam on Friday, March 27Second Exam on Friday, March 27thth

Backwashing and Trough DesignBackwashing and Trough Design

Backwashing and Trough DesignBackwashing and Trough Design

Backwashing and Trough DesignBackwashing and Trough Design

Backwashing and Trough DesignBackwashing and Trough Design

Other Questions of WTP Design?Other Questions of WTP Design?

Missing Data from Previous LLectures

• Lecture 10Lecture 10• Lecture 17

Synthetic Organic CompoundsSynthetic Organic CompoundsSynthetic Organic CompoundsSynthetic Organic Compounds•• Organic chemicals of an a________________ Organic chemicals of an a________________

origin are termed synthetic organic origin are termed synthetic organic compounds (SOCs). compounds (SOCs). Like VOCs SOCs may have particularLike VOCs SOCs may have particular•• Like VOCs, SOCs may have particular Like VOCs, SOCs may have particular adverse health effects and are a result of adverse health effects and are a result of –– industrial, industrial, ,,–– commercial, and commercial, and –– agricultural activity. agricultural activity.

•• Many SOCs are h__________, p___________, Many SOCs are h__________, p___________, or i______________.or i______________.

Disinfection ByproductsDisinfection ByproductsDisinfection ByproductsDisinfection Byproducts•• During disinfection of drinking water, chemical During disinfection of drinking water, chemical

oxidants kill disease causing organisms oxidants kill disease causing organisms g gg g(p_____________) but can also create toxic organi(p_____________) but can also create toxic organicompounds. compounds.

•• These are termed disinfection byproducts (DBPs)These are termed disinfection byproducts (DBPs)•• These are termed disinfection byproducts (DBPs).These are termed disinfection byproducts (DBPs).•• The most common source of DBPs is c__________The most common source of DBPs is c__________

or b___________ of water containing organic or b___________ of water containing organic ttttmatter. matter.

•• This often results in trihalomethanes (THMs), the This often results in trihalomethanes (THMs), the most common of which are:most common of which are:most common of which are: most common of which are: –– Chloroform (CHCl3)Chloroform (CHCl3)–– Bromoform (CHBrBromoform (CHBr33))

B di hl th (CHB ClB di hl th (CHB Cl ))–– Bromodichloromethane (CHBrClBromodichloromethane (CHBrCl22))–– Dibromochloromethane (CHBrDibromochloromethane (CHBr22Cl)Cl)

LegislationLegislationLegislationLegislation•• SDWA of 1974SDWA of 1974

–– The S____ D_________ W_____ A___ (SDWA) was The S____ D_________ W_____ A___ (SDWA) was signed into law by President Gerald Ford in 1974. signed into law by President Gerald Ford in 1974.

–– It established minimum national standards forIt established minimum national standards forIt established minimum national standards for It established minimum national standards for drinking water to protect public health. drinking water to protect public health.

–– The act established p___________ standards which The act established p___________ standards which specified maximum contaminant levels (MCLs) for specified maximum contaminant levels (MCLs) for p ( )p ( )individual contaminants suspected of having an individual contaminants suspected of having an adverse affect on public health.adverse affect on public health.

–– The act also established s__________ standards The act also established s__________ standards ____________________relating to tastes, odors, and appearance of drinking relating to tastes, odors, and appearance of drinking water.water.

–– SDWA set a timeline for the promulgation of SDWA set a timeline for the promulgation of t d d ith i tht d d ith i thstandards with a review every three years.standards with a review every three years.

SDWA Amendments of 1986SDWA Amendments of 1986•• By the 1980s, a number of contaminants had yet to be regulated, and By the 1980s, a number of contaminants had yet to be regulated, and

on June 19, 1986 President Reagan signed into law the 1986 on June 19, 1986 President Reagan signed into law the 1986 Amendments to the SDWA.Amendments to the SDWA.Amendments to the SDWA.Amendments to the SDWA.

•• Major aspects of the 1986 Amendments to the SDWA included:Major aspects of the 1986 Amendments to the SDWA included:–– C____________ revisions to drinking water regulations in a timely C____________ revisions to drinking water regulations in a timely

fashion.fashion.–– Definition of a t___________ t___________ for each contaminant Definition of a t___________ t___________ for each contaminant

regulated.regulated.–– Requirement of a treatment technique where it is not feasible to Requirement of a treatment technique where it is not feasible to

ascertain the level of a r cascertain the level of a r casce ta t e e e o a ___________ c______________asce ta t e e e o a ___________ c______________–– F___________ r_____ for surface waters (Surface Water Treatment F___________ r_____ for surface waters (Surface Water Treatment

Rule, SWTR).Rule, SWTR).–– D____________ of all water supplies.D____________ of all water supplies.

P hibi i h f l dP hibi i h f l d–– Prohibition on the use of l_____ products on conveyance systems.Prohibition on the use of l_____ products on conveyance systems.–– Requirement for the protection of g__________ sources.Requirement for the protection of g__________ sources.

•• The SDWA directed EPA to set up several classes of compounds for The SDWA directed EPA to set up several classes of compounds for which regulations are to be developed and to establish a timeline forwhich regulations are to be developed and to establish a timeline forwhich regulations are to be developed and to establish a timeline for which regulations are to be developed and to establish a timeline for development of the regulations.development of the regulations.

•

SDWA Amendments of 1996

•• On November 29 1996 the Senate passed a bill toOn November 29 1996 the Senate passed a bill toOn November 29, 1996, the Senate passed a bill to On November 29, 1996, the Senate passed a bill to r_____________ the SDWA. r_____________ the SDWA.

•• This bill contained several amendments to the This bill contained several amendments to the regulations which would lessen some of the regulatoryregulations which would lessen some of the regulatoryregulations which would lessen some of the regulatory regulations which would lessen some of the regulatory burden on water utilities, especially small systems. burden on water utilities, especially small systems.

•• It bill passed the House on June 25, 1996 and both It bill passed the House on June 25, 1996 and both hhhouses on houses on August 2, 1996. August 2, 1996.

•• These amendments locked EPA into a 1998 deadline forThese amendments locked EPA into a 1998 deadline forThese amendments locked EPA into a 1998 deadline for These amendments locked EPA into a 1998 deadline for issuing a DBP rule and enhanced SWTR.issuing a DBP rule and enhanced SWTR.

•• Subsequent review and revisions to current standards is Subsequent review and revisions to current standards is required every six yearsrequired every six yearsrequired every six years.required every six years.

Contaminant Candidate List

• Currently, EPA has drinking water regulations forCurrently, EPA has drinking water regulations for more than 90 contaminants.

• The SDWA required EPA to maintain a list of qunregulated contaminants. EPA uses this list to prioritize research and data collection efforts to determine whether to regulate a given contaminant.

• In February 2005, EPA published its second list of t i t th t i t did t li t (CCL)contaminants, the contaminant candidate list (CCL).

Currently EPA is soliciting nominations for CCL3.

ADSORPTIONADSORPTION• takes advantage of physical/chemical bond of

pollutant with adsorbent (typically gpollutant with adsorbent (typically g_________ activated carbon or p_________ activated carbon)

• one ounce of GAC has a surface area of 5 10 acres• one ounce of GAC has a surface area of 5-10 acres• good process for removal of

THMs– THMs– DBPs– SOCsSOCs– VOCs

ADSORPTIONADSORPTION• PAC dose is typically _____ mg/L can be as

high as mg/Lhigh as _____mg/L• GAC can be used instead of a________ in

dual media filtersdual media filters, – called filter adsorbers

must replace GAC every years– must replace GAC every ____ years• separate stage adsorption unit (contactor

unit)unit) – GAC must be replaced or regenerated every __

to monthsto ___ months

Practice Exam 2Practice Exam 2