ENV4001_s11_q2c_soln - Spring 201 1 Quiz #2 Wednesday, Mar....

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Unformatted text preview: Spring 201 1 Quiz #2 Wednesday, Mar. 23 ENV 4001: ENVIRONMENTAL SYSTEMS ENGINEERING University of South Florida Civil & Environmental Eng. Prof. J.A. Cunningham Instructions: . 2. 12. l3. l4. l5. l6. Name: You may read these instructions, but do not turn the page or begin working until instructed. This quiz contains three questions, each worth 20 points. Answer any two Questions. The total points possible are 40. If you answer all three questions, make sure it is very clear which two you want me to grade. Otherwise, I will grade whichever two I choose. It might not be the ones you would have selected. You will probably score higher if you focus on only two questions, rather than trying all three. it is not likely that you will have time to do a good job if you try all three questions. Some questions might have multiple parts. The point value of each part is indicated. Unit conversion factors, as well as other potentially-useful information, are provided on the back ofthis page. Answer each question in the space provided. Show your work and state any important assumptions you make. 1 cannot award partial credit if l can’t follow what you did. Report a reasonable number of significant digits in your answers. Include units in your answers. An answer without proper units is not correct! You are allowed to use your text book, your course notes, or other printed materials. You may not receive help from another person. A hand—held calculator is recommended. Other electronic devices are not permitted. Time limit: 40 minutes. Step working when asked. If you continue working after time has been called, you will be penalized at a rate of] point per minute. Don’t cheat. Cheating will result in appropriate disciplinary action according to university policy. More importantly, cheating indicates a lack of personal integrity. Please print your name legibly in the space provided below, and turn in this quiz at the end of the period. Hints: o Read each question carefully and answer the question that is asked. 0 Watch your units. If you take good care of your units, they will take good care of you. 0 Work carefully and don’t rush. Even ifyou can‘t finish the quiz, you usoally will score higher ifyou perform well on one or two problems, as opposed to performing badly on all of them. A Answer lmq, filo-g2, \lfifii‘m L4 p 1/9 Potentially useful constants: Ideal gas constant, R: 8.314 Pa-m3-mo14-K" : 82.06x10r6 atm-m3-morh1cl Gravitational acceleration, g: 9.81 111/5.2 Molecular weight of water, H20: 18.01 g/mole Density of water at 25 0c: 09970 g/mL : 997 kg/m3 Viscosity of water at 25 CC: 0.89081073 Pa-sec Density of air at 25 0C: 1.18 @0113 Viscosity of air at 25 OC: 1.85><10_5 Pa-see Potentially useful conversion factors: Pressure: 1 atm = 760 mm Hg = 760 torr = 101325 Pa Mass: 1kg:1000g=106mg=10"ng Length: 1km : 1000 m =106 mm =109 11m Temperature: 25 OC : 298.15 K Volume: 1 m3 : 1000 L = 106 mL = 106 em3 Other ; 1 Pa 2 1 Wm2 = 1 kg/(m'secz) Atomic Masses: H = 1.008 g/mole C 2 12.011 g/mole N : 14.007 g/mole O : 15.999 g/mole P = 30.974 g/mole S : 32.06 g/mole C1: 35.453 g/mole Br : 79.904 g/mole Na 2 22.99 g/moie Mg = 24.31 g/mole Ca = 40.08 g/mole Fe = 55.85 g/mole Equilibrium Concentrations of Oxygen (02) in Fresh Water (air/water equilibrium): Temperature Equil. Conc. 01°02 Temperature Equil. Cone. of 02 cc) (mg/L) cc) (mg/L) 10 11 33 21 8 99 11 11 08 22 8 83 12 10.83 23 8 68 13 10.60 24 8 53 14 10.37 25 8 38 15 10 15 26 8 22 16 9 95 27 8 07 17 9 74 28 7 92 18 9 54 29 7 77 19 9.65 30 7 63 20 9.17 31 7 51 p 2/9 1. Imagine that you are designing a set of sedimentation basins for a drinking-water treatment plant. The design capacity of the plant is 10 million gallons per day (MG-D), which is equivalent to 0.438 ms/s. Assume the water temperature is 25 DC. (a) (15 pts) Suppose that the water contains two types of flocs. Some of the flocs have a diameter of 60 um and a density of 1.3 g/cm3. The other flocs have a diameter of 200 um and a density of 1.6 g/cm3. You want to design the sedimentation basins so that they can remove 100% of both types of flocs. How much surface area is required for the sedimentation basins to ensure 100% removal of both types of flocs? Hint: compare the properties of the two types of flocs before you start your calculations. a wine/xv \Jfiomrflm raft: = [A {807. rmom :3 v5 2 v. Q \1“ Z 73‘" $ A 3 ‘67:— Um V; :— Stmkj trailed-[7 Nmtt m smihlifiw Rats 0” Tammi” 1” m "m" “M”! '0‘“ [Mitt ‘g’w‘ 9"“ DEN-f 173 math? 9555‘, M Iplj 'Hqsr ‘TLELIYE SUR’ t FW‘JCIA. 7 win r1",%‘ ‘5 \i; liar 5"“ 3 ‘v (was; wt are a» set“ film, @941 1' m a. ‘ - \L a - 3‘ TN“ V5 : 3 _ {Ia/".3 '- ‘i‘i! s/nyfpoitwb my D it». --——-—-——————~——«--——__.___———- “ 18 (with his PM) vs ' 0000098 "/5 : our; v 15“ “V; “a ’1 ' t 3'4 M -L tutti Rt __ : GM? A“ BUD-M3 1 /SB((aO“iU M) I” 0-“ i [5'3 Pox-s Re= 0-0148 < t / Shim Hm W1 ‘5, vs: {5193* is“ N]; in: shalt {Cains problem 1 continues *9 p 4/9 1. continued a. continued (more space to work on part a) _51 o-les Ms A 2 = —. (0% 3 V5 x I'D-H MIS A2 (05b ML '7: Sucre—Nita, {007, Hyundai. 5(— ‘offifi tum a? Hoe; b. (5 pts) Suppose you want the sedimentation basins to be 50 m long and 3 m deep. How wide will you make each basin, and how many basins will you need? Tmfll'wlij Fruit. L 1W ’5 (9‘1, Ia 1i- L= Sb M, 59} mpg M W93 ead- \Qbsifi if fin ink; x 8 m with X 3 f». Sodom area «Ear their besm : (93 «3U m3 = 400 a“ Two basins DL 8 M Mafia win 99m. (300 Mlvcscax} WMUU‘J .L mist if‘ & "Rd-"L Basin. (“A an 8 :0 3a) NIL—“0 OAlj TWO, FQSJJLEU-L 9 7' 0 L. hrs/3- : 547“ 5 z 1.3 hr Tina '5 R “m iow. Wi'fin a Basin} 9 r, “36$ “‘3 (3 M} 05433 “is t 5 Z LF \Damf J A‘Sa W PA“ 0" fiumg 0“ A.“ 551754215 “C U11 (ti/“0.93 3 £3351”; Qgcammemfi Three Basia; .1: m mafia, TKJJL fun: LJDJLQ ‘1 OK. p 5/9 2. The movie “Erin Brockovich” is based on the true story of the City of Hinkley, California. People in Hinkley were exposed to hexavalent chromium, Cr(Vl), which can cause cancer when inhaled. (It is not yet clear if Cr(VI) causes cancer when ingested.) It has been reported that, over a 12—year period, 196 residents of Hinkley were diagnosed with cancer. The population of the city is about 2,000 people. Therefore, the rate at which people contract cancer in Hinkley is about 820 cases per 100,000 people per year. The average cancer rate in nearby parts of California is about 360 cases per 100,000 people per year. a. (5 pts) Estimate/calculate the lifetime incremental risk of contracting cancer for a person living in Hinkley. (Note that “incremental risk” means the risk over—and—above the “normal” background level.) State any assumptions that you make. I V 310 CAR 5 300 cases 400 Law; .5. ff?) S :1 if d : 100,000 Yup «if [00,000 Pvqu Air 109,000 Pugh - gr ASSN“? AVULBL liltch (gran a; 70 wifS W“) 00%; 8 31.200 €12.36; Than hie—Tum it‘ine/C‘Cni fish = L70 ‘iff\( [00,000 Pu;le - or — 190,99.) Egg-La Li l-“Crl’ Weft-J rider. 1 0 b. (3 pts) Do you think the incremental risk for people living in Hinkley is acceptable? Why or why not? _.-v ‘irg rig“. 96“] £6“, gilt 'fikmfl [£ka NE t k, ‘1 Vl n “'0’ “‘1 caulk Acmfloblfi —- l0 ‘ lo . W1; is dumb! unacceflglgle. problem 2 continues ~> p 6/9 "tu’f’ Toto it. 3301 (fit 2. continued c. (12 pts) It is widely believed that people in Hinkley were exposed to Cr(VI) in their air, and that is what caused the higher-than—norrnal incidence of cancer in the town. Let’s estimate that, on average, the concentration of Cr(VI) in the air was 0.05 mg/mB. (I have no idea if this is accurate, but let’s just use it as an estimate.) Estimate the slopefacror for contracting cancer by inhalation of Cr(V1). Clearly state any assumptions you make. LtCeTtm risk : aloft LmTar EL OBI. We. tuba, lfk’lizva risls = 03?. (Few peel (A Wm» .2; col? ASSN 1m the We at, mama, MW 1W ;, [4MB] 5”, 30 W Dumj "ltd law The»! mm “in Tam” 4w 39> (tr/1r. [5&7 W“ Z 70 k3 Nu+ magma} +. "uni-1&2 My: tutu-w THAL a“ “‘“W’fhmj // Break»; (it! =‘- 2O M3Al‘- "" Cr “‘3 “7" 39’ 0‘ So I: realm/w; TthA _—_ M} "if A y ( 36’)” 7&7 1r: Hidth 3 70 L5 1:3on Mass M3 Cr CD: = 0.00581 NEE urea COJLKD Klimt: :- CBI pd)“ agtuMfi'lu'aMu-ch‘l‘s 0V. 4C Mc‘fiw ml; 0. 397)— Sl‘l“ “T” ‘ CHI * 0.90657 "7:341 MD ‘l slog/1L {:06le 7- A315) p 7/9 . Imagine that a factory is discharging its waste into the Lynn River. The factory waste contains a lot of contaminants that exert an oxygen demand in the river. Here is what we know about the river. 0 Just downstream of the factory discharge pipe, the concentration of contaminants in the river, expressed as oxygen demand, is equal to 25 mg/L. 0 The river temperature is 15 OC. 0 The average river velocity is 0.133 m/s, which is equivalent to l 1.5 kin/d. o The deoxygenation rate constant in the river is approximately 0.25/d. o The reaeration rate constant in the river is approximately 0.80/d. o The oxygen concentration in the river was measured 3.5 km downstream of the factory discharge. The measured oxygen concentration at that location was 6.30 mg/L. a. (14 pts) Based on the data provided above, at what distance downstream of the discharge pipe will the oxygen concentration be lowest? Report your answer in km. 1 b; [: 1 Do ( k1- t1- k. l“ r. ’ “ r1 L. iflL': Lu:— Mj/L ) tau-i“ nil-’3 Ari}; ‘ e t he tug 2 wt lama lap-0.75M rt, Mo: \LJa; 6 'L Wm x: as \m, [0;] = (0.30 P“le :> b = ID” "9-7)" s 3'35 , M Moos) .2 [0.13 HELL? 3h.) 1W w; ‘( ll-S‘ H i _ (9.1?)[153 H [D-EQ)(3X):( 3.33 .t (ow/A - sis/53 E .. e ‘5” 6 Ms : U30 13>(Mla‘j , 0.13391} + Do (0783?) @35 MIL) ~ (irate/mamas) a 0 mm 0?. 817’ (“j/L _.___.- problem 3 continues '9 p 8/9 it“) T. 3. continued a. continued (more space to work on part a) t I ML! “5/ )[o-Eofd— 0.1mm 1,? ter = -—--——— fin E m [1~C L“ L? Molt; - Olfld oi? (0.15m (25 “3M ‘ 2.931 6 Kit.” = = I‘M dbwflfl—(‘CAM 0" dint/mfg .___—- b. (6 pts) What will be the minimum concentration of dissolved oxygen in the river? Report your answer in mg/L. if. (“.1- [1 Kurt ltLY-gri‘! Lt, [ _ 4.7 _ 3.7.. _ .. ~+ Der-T : Ill—\él e, " be e, WCO—l?lé§(l§ NJ}le "(0.10098 “(OASOYL‘S‘P’J m3 40.363050 (01%0/d—~ aux/a) (L - e 4» (2m 1 e I' = Qt'bta “Rafi/Lilac?» - 0130;) + (2.3L: "3L3 (0.1803) :~_ (3.73 “‘le cn't'm‘ Milt—i M M M ioflm = {mg *3 — 317‘? :1 Lift ‘WL «‘7 Wj 3?“ ‘“ W“ M END OF QUIZ p 9/9 ...
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ENV4001_s11_q2c_soln - Spring 201 1 Quiz #2 Wednesday, Mar....

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