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CE 380 Environmental Science and Engineering 1 Slide 2 Assignment Write on a piece of paper your name and your answer to the following question: What do environmental engineers do? 2 Slide 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 Slide 4 Assignment Write on the same piece of paper your answer to the following question: Why do you need to know this stuff? 4 Slide 5 Course Organization Solid Waste Hazardous and Radioactive Waste Air Noise Pollution Water Wastewater Sustainability 5 Slide 6 Primary Chapter: 1 Supplemental Chapter: 17 6 Slide 7 Sustainability 7 Slide 8 8 Slide 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 Slide 10 Water, Part 1 Primary Chapter: 10 Supplemental Chapters: 3, 9 10 Slide 11 WATER QUANTITY & SOURCES Section 10.1 11 Slide 12 Water on Earth Total Water Supply Fresh Water Supply Salt Water Supply Available Fresh Water Supply 12 Slide 13 13 Slide 14 Potable Water Sources Deep Wells Shallow Wells Intakes Springs Fresh and Saline 14 Slide 15 U.S. Water Use 15 Slide 16 U.S. Water Withdrawals in 2005 16 Slide 17 WATER QUALITY Sections 9.1 9.2 17 Slide 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 Slide 19 REVIEW: LAWS AND REGULATIONS 19 Slide 20 The Process Public concern and/or a recognition of link between cause and effect Law Regulations 20 Slide 21 Federal Government 21 Slide 22 DRINKING WATER LEGISLATION Section 9.3 22 Slide 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 Slide 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 Slide 25 Activity - 3 What are the differences between primary and secondary standards? A. Enforceability B. Purpose C. Size of plant covered 25 Slide 26 No Reported Violations 26 Slide 27 DRINKING WATER TREATMENT Section 10.2 27 Slide 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 Slide 29 Process for POTWs 29 Slide 30 Intake Horizontal Centrifugal Pump Surge Tank Screw 30 Slide 31 General Water Treatment Conventional Vs. Advanced 31 Slide 32 SOFTENING Section 10.2.1 32 Slide 33 Why? Why do we soften water? 33 Slide 34 Why? 34 Slide 35 What? What is hardness? 35 Slide 36 How? How do we soften water? 36 Slide 37 Units How do we get to from mg/L of ions to mg/L as CaCO 3 ? = ? 37 Slide 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 = 7.5 38 Slide 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 Slide 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 Slide 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 doesnt make sense, check. If your check gives you the same answer, state why it doesnt make sense. 41 Slide 42 More on Total Hardness TH = CH + NCH 42 Slide 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 Slide 44 Alkalinity 44 Slide 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 = 7.5 45 Slide 46 Reminder Calculate TH and ALK. Determine CH. Calculate NCH. 46 Slide 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 = 7.5 47 Slide 48 Reminder Calculate 1. CCH. 2. CNCH 3. MCH 4. MNCH Check your calculations! 48 Slide 49 Lime-Soda Softening Hard Water Lime and/or Soda Ash Mixing Flocculation Sedimentation Recarbonation Soft Water CO 2 Sludge Sedimentation Sludge 49 Slide 50 Lime-Soda Softening CO 2 : CO 2 + 1 Ca(OH) 2 1 CaCO 3 + H 2 0 CCH: Ca(HCO 3 ) 2 + 1 Ca(OH) 2 2 CaCO 3 + 2 H 2 O CNCH: CaSO 4 + 1 Na 2 CO 3 1 CaCO 3 + Na 2 SO 4 MCH: Mg(HCO 3 ) 2 + 1 Ca(OH) 2 1 CaCO 3 + MgCO 3 + 2 H 2 O MgCO 3 + 1 Ca(OH) 2 1 Mg(OH) 2 + 1 CaCO 3 MNCH: MgSO 4 + 1 Na 2 CO 3 MgCO 3 + Na 2 SO 4 MgCO 3 + 1 Ca(OH) 2 1 Mg(OH) 2 + 1 CaCO 3 50 Slide 51 Excess Lime 51 Slide 52 If were trying to take calcium out of the water, why do we add lime, which is a calcium-based chemical? 52 Slide 53 Example Softening To solubility limits with 90% quicklime, 90% soda ash 5 MGD flowrate 53 Slide 54 Example continued First: Determine TH 54 Slide 55 Ca 2+ HCO 3 - SO 4 2- Mg 2+ Na + Cl - CO 2 03.54.34.6meq/L Example continued Second: Determine speciation 55 Slide 56 Example continued Third: Determine chemical amounts (Section 3.1.3) 56 Slide 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 Slide 58 Example continued Fourth: Determine sludge quantity 58 Slide 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 Slide 60 Selective Ca 2+ Removal If Mg 2+ 40 mg/L as CaCO 3 (maximum Mg hardness) 60 Slide 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 Slide 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 Slide 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 Slide 64 Ion Exchange Softening 64 Slide 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 Slide 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 280.0 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 Slide 67 MIXING Section 3.1.2 67 Slide 68 Mixing Rapid Mix Tank Fine Air Diffusers Parshall Flume 68 Slide 69 Design Equation Design Equation: Hydraulic Retention Time (Section 3.1.4) 69 Slide 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 Slide 71 SOLIDS REMOVAL Sections 10.2.2 and 10.2.3 71 Slide 72 Coagulation and Flocculation (Section 10.2.2) 72 Slide 73 Flocculator Horizontal Shaft Type Vertical Shaft Type Baffled Flow Type 73 Slide 74 Solids by Size (Section 9.1.3) 74 Slide 75 Coagulation & Flocculation Al -13 Polycation Fe-12 Polycation 75 Slide 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 Slide 77 Sedimentation (Section 10.2.3) 77 Slide 78 Sedimentation Purpose: Remove solids 78 Slide 79 Sedimentation: Another View 79 Slide 80 Design Equation: Design Equation: Overflow Rate 80 Slide 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 Slide 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 Slide 83 FILTRATION Section 10.2.4 83 Slide 84 Filtration 84 Slide 85 Filtration Methods Gravity Filters Upflow Filter Biflow Filter Pressure Filter 85 Slide 86 Filtration Mechanisms 86 Slide 87 Slow vs. Rapid Sand Filters 87 Slide 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 Slide 89 DISINFECTION Sections 9.1.5 and 10.2.5 89 Slide 90 Disinfection 90 Slide 91 Activity - 1 Why is drinking water disinfected? 91 Slide 92 Activity - 2 Who linked contaminated water to infectious disease? A. Leonard McCoy B. John Snow C. Marcus Welby 92 Slide 93 Activity - 3 When was the discovery made? A. 1600s B. 1700s C. 1800s 93 Slide 94 Activity - 4 In general, what is an indicator organism and why is it used? 94 Slide 95 Size Comparison 10 microns 0.05 - 0.1 m 0.5 - 1.5 m 5 m 60 m Virus Bacteria Red Blood Cell Sperm 95 Slide 96 Pathogen Removal/Inactivation Where does this occur in a water treatment plant? 96 Slide 97 Activity - 5 What are the options for disinfecting water? 97 Slide 98 Activity - 6 What are characteristics of the ideal disinfectant? 98 Slide 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 Slide 100 Chlorination chlorinator 100 Slide 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 Slide 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 Slide 103 Ultraviolet Light Hg Vapor 103 Slide 104 Ozonation 104 Slide 105 STORAGE AND DISTRIBUTION Section 10.3 105 Slide 106 Storage and Distribution 106 Slide 107 SLUDGE MANAGEMENT 107 Slide 108 Sludge Management 108 Slide 109 OTHER TREATMENT OPTIONS Section 10.2.6 109 Slide 110 Lead 110 Slide 111 Membrane Treatment 111 Slide 112 112 Slide 113 113 Slide 114 Phoenix Proposed WTP 114 Slide 115 In-Class Activity Why would an industrial plant treat incoming potable water? Why would a resident treat incoming potable water? 115