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CE 380 Environmental Science and Engineering 1. Assignment Write on a piece of paper your name and your answer to the following question: What do environmental.

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Presentation on theme: "CE 380 Environmental Science and Engineering 1. Assignment Write on a piece of paper your name and your answer to the following question: What do environmental."— Presentation transcript:

1 CE 380 Environmental Science and Engineering 1

2 Assignment Write on a piece of paper your name and your answer to the following question: What do environmental engineers do? 2

3 Environmental Engineering (Section 1.1) In general: The application of scientific and engineering principles to minimize the adverse effects of human activity on the environment and to safeguard human health and welfare 3

4 Assignment Write on the same piece of paper your answer to the following question: Why do you need to know this stuff? 4

5 Course Organization Solid Waste Hazardous and Radioactive Waste Air Noise Pollution Water Wastewater Sustainability 5

6 Primary Chapter: 1 Supplemental Chapter: 17 6

7 Sustainability 7

8 8

9 Assignment – Due Fri. Answer the following questions. 1. What is sustainability? 2. How does it pertain to civil engineering? 3. What are the potential pros and cons of integrating sustainability into projects/policies? 9

10 Water, Part 1 Primary Chapter: 10 Supplemental Chapters: 3, 9 10

11 WATER QUANTITY & SOURCES Section

12 Water on Earth Total Water Supply Fresh Water Supply Salt Water Supply Available Fresh Water Supply 12

13 13

14 Potable Water Sources Deep Wells Shallow Wells Intakes Springs Fresh and Saline 14

15 U.S. Water Use 15

16 U.S. Water Withdrawals in

17 WATER QUALITY Sections 9.1 –

18 Exercise Water, water everywhere but which drop can you drink? Would you drink this? What about it makes it seem okay or not? 18

19 REVIEW: LAWS AND REGULATIONS 19

20 The Process Public concern and/or a recognition of link between cause and effect Law Regulations 20

21 Federal Government 21

22 DRINKING WATER LEGISLATION Section

23 Activity - 1 Where can promulgated (final) federal laws and regulations be found? A. Federal Register B. Code of Federal Regulations C. Washington Times 23

24 Activity - 2 What is the primary law regulating drinking water treatment? A. Safe Drinking Water Act B. Clean Water Act C. Resource Conservation and Recovery Act 24

25 Activity - 3 What are the differences between primary and secondary standards? A. Enforceability B. Purpose C. Size of plant covered 25

26 No Reported Violations 26

27 DRINKING WATER TREATMENT Section

28 Drinking Water Treatment Primary goal: Prevention of disease Secondary goals: Good taste, odor, and color Low hardness Meet irrigation and fire protection needs 28

29 Process for POTWs 29

30 Intake Horizontal Centrifugal Pump Surge Tank Screw 30

31 General Water Treatment Conventional Vs. Advanced 31

32 SOFTENING Section

33 Why? Why do we soften water? 33

34 Why? 34

35 What? What is hardness? 35

36 How? How do we soften water? 36

37 Units How do we get to from mg/L of ions to mg/L as CaCO 3 ? ± = ? 37

38 Example Find total hardness (in mg/L as CaCO 3 ) of water containing: Ca 2+ = 80 mg/L, Mg 2+ = 30 mg/L, Pb 2+ = 160 mg/L, Fe 3+ = 50 mg/L Na + = 72 mg/L, K + = 6 mg/L Cl - = 100 mg/L, SO 4 2- = 201 mg/L, HCO 3 - = 165 mg/L pH =

39 Units (Section 3.1.2) ppm vs. mg/L 1 ppm is equivalent to 1 minute in: a) 1 day b) 2 years c) 6 weeks 39

40 Approximations and Sig Figs (Section 3.2) Consider: Problem 3.26 (p. 108) Problem 3.27 (p. 108) Problem 3.29 (p. 108) 40

41 Reminder Hints for Quantitative Problems Write down the general equation. Write down your units throughout! And use them to come up with your final units. Be reasonable with sig figs. Ignore irrelevant data. If your answer doesn’t make sense, check. If your check gives you the same answer, state why it doesn’t make sense. 41

42 More on Total Hardness TH = CH + NCH 42

43 Calculating Alkalinity CO 2 CO 2 (aq) + H 2 O H + + HCO 3 - H + + CO 3 2- Limestone (CaCO 3 ) + Ca 2+ H + + OH - 43

44 Alkalinity 44

45 Example Find carbonate and noncarbonate hardness of water containing: Ca 2+ = 80 ppm, Mg 2+ = 30 ppm, Pb 2+ = 160 mg/L, Fe 3+ = 50 mg/L Na + = 72 ppm, K + = 6 ppm Cl - = 100 ppm, SO 4 2- = 201 ppm, HCO 3 - = 165 ppm pH =

46 Reminder Calculate TH and ALK. Determine CH. Calculate NCH. 46

47 Example Find the speciation of the hardness of water containing: Ca 2+ = 80 mg/L, Mg 2+ = 30 mg/L, HCO 3 - = 165 mg/L pH =

48 Reminder Calculate 1. CCH. 2. CNCH 3. MCH 4. MNCH Check your calculations! 48

49 Lime-Soda Softening Hard Water Lime and/or Soda Ash Mixing Flocculation Sedimentation Recarbonation Soft Water CO 2 Sludge Sedimentation Sludge 49

50 Lime-Soda Softening CO 2 : CO Ca(OH) 2  1 CaCO 3  + H 2 0 CCH: Ca(HCO 3 ) Ca(OH) 2  2 CaCO 3  + 2 H 2 O CNCH: CaSO Na 2 CO 3  1 CaCO 3  + Na 2 SO 4 MCH: Mg(HCO 3 ) Ca(OH) 2  1 CaCO 3  + MgCO H 2 O MgCO Ca(OH) 2  1 Mg(OH) 2  + 1 CaCO 3  MNCH: MgSO Na 2 CO 3  MgCO 3 + Na 2 SO 4 MgCO Ca(OH) 2  1 Mg(OH) 2  + 1 CaCO 3  50

51 Excess Lime 51

52 If we’re trying to take calcium out of the water, why do we add lime, which is a calcium-based chemical? 52

53 Example – Softening To solubility limits with 90% quicklime, 90% soda ash 5 MGD flowrate 53

54 Example continued First: Determine TH 54

55 Ca 2+ HCO 3 - SO 4 2- Mg 2+ Na + Cl - CO meq/L Example continued Second: Determine speciation 55

56 Example continued Third: Determine chemical amounts (Section 3.1.3) 56

57 Assumptions ALWAYS clearly state you are making an assumption and what that assumption is. Examples: Assume purity = 98% Assume generation = 4.2 lb/c/d 57

58 Example continued Fourth: Determine sludge quantity 58

59 Split Treatment - LS Softening Plant Influent Lime and/or Soda Ash Mixing Flocculation Sedimentation Soft Water Sludge Hard Water To Rest of Treatment Soft Water Recarbonation CO 2 59

60 Selective Ca 2+ Removal If Mg 2+ ≤ 40 mg/L as CaCO 3 (maximum Mg hardness) 60

61 Examples Can selective Ca 2+ removal be used if all the hardness is Ca 2+ and Mg 2+ ? 1.TH = 210 mg/L as CaCO 3 Ca 2+ = 120 mg/L as CaCO 3 2.TH = 180 mg/L as CaCO 3 Ca 2+ = 138 mg/L as CaCO 3 61

62 Example Continued TH = 180 mg/L as CaCO 3 Ca 2+ = 138 mg/L as CaCO 3 Mg 2 + = 42 mg/L as CaCO 3 Calculate the amount of quicklime and soda ash required in meq/L if you (1) remove the Mg 2+ and (2) leave the Mg 2+ (selective Ca 2+ removal). Assume ALK = 105 mg/L as CaCO 3 and CO 2 = 20 mg/L as CaCO 3. 62

63 Other Benefits of LS Softening Removal of other metals, arsenic, & uranium Reduction of solids, turbidity, & TOC Inactivation of bacteria & viral removal Prevention of corrosion Removal of excess fluoride 63

64 Ion Exchange Softening 64

65 Softening Softening reaction: Na 2 R + Ca(HCO 3 ) 2  CaR + 2 Na(HCO 3 ) Regeneration reaction CaR + 2 NaCl  Na 2 R + CaCl 2 65

66 Example An ion exchange water softener has 0.1 m 3 of ion-exchange resin with an exchange capacity of 57 kg/m 3. The occupants use 2,000 L of water per day. If the water contains mg/L of hardness as CaCO 3 and it is desired to soften it to 85 mg/L as CaCO 3, how much should be bypassed? What is the time between regeneration cycles? 66

67 MIXING Section

68 Mixing Rapid Mix Tank Fine Air Diffusers Parshall Flume 68

69 Design Equation Design Equation: Hydraulic Retention Time (Section 3.1.4) 69

70 In-Class Activity A 0.5-MGD water treatment plant will use one flash mixer designed for a 1-minute retention time. Determine the diameter of the mixer. Assume the water depth will equal 80% of the diameter. 70

71 SOLIDS REMOVAL Sections and

72 Coagulation and Flocculation (Section ) 72

73 Flocculator Horizontal Shaft Type Vertical Shaft Type Baffled Flow Type 73

74 Solids by Size (Section 9.1.3) 74

75 Coagulation & Flocculation Al -13 Polycation Fe-12 Polycation 75

76 Chemical NameChemical FormulaPrimary CoagulantCoagulant Aid Aluminum sulfate (Alum)Al 2 (SO 4 ) 3 · 14 H 2 OX Ferrous sulfateFeSO 4 · 7 H 2 OX Ferric sulfateFe 2 (SO 4 ) 3 · 9 H 2 OX Ferric chlorideFeCl 3 · 6 H 2 OX Cationic polymerVariousXX Calcium hydroxide (Lime)Ca(OH) 2 X*X Calcium oxide (Quicklime)CaOX*X Sodium aluminateNa 2 Al 2 O 4 X*X BentoniteClayX Calcium carbonateCaCO 3 X Sodium silicateNa 2 SiO 3 X Anionic polymerVariousX Nonionic polymerVariousX 76

77 Sedimentation (Section ) 77

78 Sedimentation Purpose: Remove solids 78

79 Sedimentation: Another View 79

80 Design Equation: Design Equation: Overflow Rate 80

81 In-Class Activity The detention time and overflow rate for a circular settling basin were determined to be 1.5 h and 0.5 gpm/ft 2, respectively. The flow rate will be 250,000 gpd. Calculate the dimensions of the basin. 81

82 In-Class Activity A 2-MGD water treatment plant will use two rectangular sedimentation basins designed for a 3-hour total detention time. If the basins will be twice as long as wide, what will be their dimensions? What will be the OFR for each basin? Assume the water depth will equal the width. 1. Assume parallel flow. 2. Assume series flow. 82

83 FILTRATION Section

84 Filtration 84

85 Filtration Methods Gravity Filters Upflow Filter Biflow Filter Pressure Filter 85

86 Filtration Mechanisms 86

87 Slow vs. Rapid Sand Filters 87

88 Typical Gravity Filter Wash-water trough Underdrain System Sand, 0.65 m Gravel, 0.5 m Freeboard, 0.6 m 0.5 m Water level during filtering Water level during backwash 88

89 DISINFECTION Sections and

90 Disinfection 90

91 Activity - 1 Why is drinking water disinfected? 91

92 Activity - 2 Who linked contaminated water to infectious disease? A. Leonard McCoy B. John Snow C. Marcus Welby 92

93 Activity - 3 When was the discovery made? A. 1600s B. 1700s C. 1800s 93

94 Activity - 4 In general, what is an indicator organism and why is it used? 94

95 Size Comparison 10 microns  m  m 5  m 60  m Virus Bacteria Red Blood Cell Sperm 95

96 Pathogen Removal/Inactivation Where does this occur in a water treatment plant? 96

97 Activity - 5 What are the options for disinfecting water? 97

98 Activity - 6 What are characteristics of the ideal disinfectant? 98

99 Activity - 7 Adequate disinfection is a balance between which two variables? A. Concentration and Time B. Concentration and Flow rate C. Flow rate and Surface area 99

100 Chlorination chlorinator 100

101 Chlorine Demand or Breakpoint Chlorination Chlorine added Chlorine residual Breakpoint Chlorine removal by reducing compounds Chloro- organic and chloramine formation Chloro- organic and chloramine destruction Formation of free chlorine Free Residual Combined Residual 101

102 In-Class Activity If 1.5 mg/L of chlorine is being used and the demand is 1.2 mg/L, what is the residual? For the same plant, if 550,000 gpd is being treated and chlorine will be bought in 1-ton containers, how long will one container last? 102

103 Ultraviolet Light Hg Vapor 103

104 Ozonation 104

105 STORAGE AND DISTRIBUTION Section

106 Storage and Distribution 106

107 SLUDGE MANAGEMENT 107

108 Sludge Management 108

109 OTHER TREATMENT OPTIONS Section

110 Lead 110

111 Membrane Treatment 111

112 112

113 113

114 Phoenix Proposed WTP 114

115 In-Class Activity Why would an industrial plant treat incoming potable water? Why would a resident treat incoming potable water? 115


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