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Water Quality Chapter 6 Water Sources

Water Quality Chapter 6 Water Sources. WQT 121 Lecture 1. How was the reading assignment?. Awesome (5 star) Good (4 star) Ok (3 star) Bad (2 star) A waste of my time (1 star). Objectives . Reading assignment: Handout: Chapter 6 Water Quality.

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Water Quality Chapter 6 Water Sources

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  1. Water QualityChapter 6 Water Sources WQT 121 Lecture 1

  2. How was the reading assignment? • Awesome (5 star) • Good (4 star) • Ok (3 star) • Bad (2 star) • A waste of my time (1 star)

  3. Objectives Reading assignment: Handout: Chapter 6 Water Quality • Review Principle Water Quality Characteristics • Understand common secondary MCLS. • Effect of pH, Taste, Odor, Corrosion on water quality • Review of MCLS & key contaminants in water 4. Hard verse soft water

  4. Mineralogical Analysis of Water • Concentration (Mg/L) Quantity of a constituent in a standard volume (1 liter) is measured by its weight (in milligrams). 1 ppm (old school) = 1mg/L (correct) • General Mineral Content Ca, Na, Mg, Fe, Mn, HCO3, CO3, SO4 and Cl2. • Rivers < 500 mg/L to 2,000 mg/L • Groundwater 100-10,000 mg/L

  5. In the water treatment field, mg/L and ppm are considered to be equivalent units. • True • False

  6. 3.5% salinity or 35,000 TDS (mg/L), 10,5000 mg/L Na, 19,700 mg/L Cl2, 2,650 mg/L SO4, 1,310 mg/L Mg, Ca 410 mg/L, Br 65 mg/L, Bicarbonate 152 mg/L, pH 8.1 • Rainwater • Seawater • Lake Water • Groundwater

  7. Groundwater in comparison to surface water is generally: • Lower in turbidity and higher in mineral content • Higher in turbidity and lower in mineral content • More susceptible to seasonal changes • More susceptible to algal blooms • Warmer and is quite soft

  8. 7.1 TDS mg/l, 7 mg/L Na, 1 mg/L Cl2, 2 mg/L SO4, 0.74 mg/L Mg, Ca 5.5 mg/L, pH 6.9 • Rainwater • Seawater • Lake Water • Groundwater

  9. 180 TDS mg/l, 7 mg/L Na, 23 mg/L Cl2, 40 mg/L SO4, 8.6 mg/L Mg, Ca 53 mg/L, pH 6.0-8.5 • Rainwater • Seawater • Lake Water • Groundwater

  10. Key Words • Dissolved Solids very stable inorganic or organic substances that remain in suspension. • Colloidal Solids Tiny clay and organic materials that float in water and repel each other. • Suspended Solids Large particles of silt and sand that settle out in a sedimentation basin or clarifier. • National Secondary Drinking Water Regulations (NSDWRs): are non‑enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water

  11. Turbidity and Corrosion • Turbidity: A measure of the light scattering property of water • The unit of measure is the NEPHELOMETRIC TURBIDITY UNIT, or NTU. • Corrosion: The destruction of metal by electro-chemical processes. • Corrosion is simply natures way to return metals back to their natural state: OXIDES

  12. Corrosion Factors • Low pH, which is often associated with EXCESS CARBON DIOXIDE in water • High oxygen • High total dissolved solids (salts) in the form of chlorides or sulfates • Soft water, or low hardness water • High temperature often exaggerates corrosion problems • 6. Low alkalinity

  13. Corrosion Controls • Aggressive soil and water • Protective coatings inside and outside of pipe (cement lining is very effective for ductile iron pipe plastic wrap can effectively protect ductile iron pipe from soil corrosion) • 2.Cathodic protection, using zinc or magnesium sacrificial anodes to coat • 3.Adjust water chemistry by increasing the pH, adding alkalinity, or adding hardness ions • 4. Galvanic corrosion • Electro-chemical process similar to a battery that occurs when dissimilar metals are joined.

  14. What does TDS stand for? • Total dissolved solids • Temporarily dissolved solids • Total disaggregated solids • Total dissolved salts

  15. The total solids in water would be a combination of: • Fixed solids and settleable solids • Dissolved solids and volatile solids • Dissolved solids and suspended solids • Suspended solids and fixed solids • Fixed solids and dissolved solids

  16. Total Dissolved Solids are dried at this temperature • 103oC • 105oC • 180oC • 550oC

  17. The secondary MCL for TDS in drinking water is? • 10 mg/L • 500 mg/L • 1,000 mg/L • 1 mg/L

  18. Key Words • TurbidityA measure of the light scattering property of water (cloudiness) • The unit of measure is the NEPHELOMETRIC TURBIDITY UNIT, or NTU. • CorrosionThe destruction of metal by electro-chemical processes. • Corrosion is simply natures way to return metals back to their natural state: OXIDES

  19. NTU stands for? • Nephelometric turbidity unit • Nephelometric total solids utilization • Nepelometric turbidity utilization • Nominal Turbidity Unit • Nominal Tubidity Utilization

  20. Turbidity is caused by? • Dissolved solids • Suspended particles • Dissolved gases • Dissolved colored solids

  21. Which of the following is a major part of a turbidimeter? • light • aspirator • Reference electrode • Objective nosepiece

  22. Turbidimeters must be calibrated: • Monthly • Quarterly • If factory calibrated, never • Daily • Weekly

  23. Which of the following parameters is used to indicate the clarity of water? • pH • Chlorine residual • Turbidity • Bacteriological

  24. Which of the following substances will reduce the effectiveness of chlorine disinfection? • color • radon • Turbidity • Carbon dioxide

  25. According to the Interim Enhanced Surface Water Treatment Rule, a public water system serving a population of 10,000 or more must maintain the combined effluent turbidity of direct or conventional filtration 95% of all measurements taken each month at : • ≤0.3 ntu • ≤0.5 ntu • ≤1.0 ntu • ≤5.0 ntu

  26. The conductivity of the source water indicates the quantity of dissolved material present • True • False

  27. In general for every 10 units of Electrical Conductance reported represents 6 to 7 mg/L increases of dissolved solids • True • False

  28. Electrical Conductance is reported in mmhos/cm at 25oC. • True • False

  29. Color • Apparent color: from light that is reflecting off the particles (giving it a yellow or straw color) • True color: tea color that remains after filtering (organic acids from vegetation) • Units are CU or color units

  30. What is apparent color? • Color in a sample after it is filtered • Color in a sample before it is filtered • Color in a sample after it is disinfected • Color in a sample before it is disinfected

  31. __________ can interfere with a turbidity meter measurement. • SS concentration • pH • Color • Temperature

  32. Sludge accumulations in settling basins over a period of time usually: • Add hardness to the water • Increase the algae growth • Result in taste and odor problems • Result in the growth of pathogenic organisms

  33. As water temperatures decrease, the disinfecting action of chlorine: • Decreases • Increases • Remains the same • Depends on the altitude As temperatures increase chemical reactions speed up Arrhenius equation: reaction rate doubles every 10 degree celsius

  34. Lake Stratification • Epilimnion- top of the lake • Thermocline- middle layer that may change depth throughout the day • Hypolimnion- bottom layer • Temperature change- from season create a cyclic pattern that is repeated from year to year.

  35. The formation of layers of different temperature in a body of water is called what? • Thermal stratification • Thermal justification • Limnoptic layering • Limnoptic stratification

  36. Reservoir turnover is? • Related to the pH of water • Caused by denser water at the surface sinking toward the bottom • Caused by wind cracking ice on the surface • Needed to control algae growth

  37. Hard vs Soft Water • 1. Hard Water • Hard water is any water containing an appreciable quantity of dissolved minerals. > 250 mg/L (mostly Ca+2 and Mg+2). • Precipitates on pipes, Soap hard to lather because it reacts with Ca and Mg salts in hard water. Need to use ion exchange or treat with lime • 2. Soft Water • Soft water is treated water in which the only cation (positively charged ion) is sodium.

  38. Hardness #2340 • What are typical values in nature? • Classification mg/L Soft 0 - 17.10 Slightly hard 17.1 - 60 Moderately hard 60 - 120 Hard 120 – 180 Very Hard 180 & over Drinking water average is about 250 mg/L as calcium carbonate hardness

  39. Hardness #2340 How is it done? Before w/ indicator After EDTA titration To endpoint

  40. Hardness #2340 • What are the units and conversions? • hardness in mg/l as CaCO3 Calculations and Formulas? Hardness as CaCO3 mg/L= (ml of EDTA (sample) – ml of EDTA (blank))(0.01 M EDTA)(100 mg=CaCO3 milliMole)(1000 ml/L) ml of sample volume titrated

  41. Hard Waters in the USA

  42. Alkalinity and hardness are both analyzed by adding a known reagent to the sample. This process results in a ______ change. • Color • Temperature • Time • Ionic strength

  43. This is the titrant used for the Hardness analysis. • EDTA - A Chelating Agent • 0.03 N Sulfuric acid • 0.125 N Hydrochloric acid • Sodium hydroxide

  44. Hardness is defined as the sum of the _____ and ____ ions, although any divalent metal ion can contribute to hardness. • Calcium and Magnesium • Magnesium and Sodium • Calcium and Sulfate • Struvite

  45. pH • Definition: The potential of hydrogen. Negative log of the hydrogen ion activity/concentration. • Formula pH= -log10(αH+) • The pH scale: • -?.................................. 7 ....................................14 • Acid Neutral Basic • The pH range for drinking water is 6.5 to 8.5

  46. Some characteristics of water, such as pH and dissolved oxygen, change so quickly that they need to be measured immediately. • True • False

  47. Acid-Base pH Balance Figure 2.7

  48. Which of the following pH readings indicates an acidic source water? • 3 • 7 • 9 • 12

  49. A water with a pH value of 7.00 is considered to be: • Basic • Acidic • Hot • Neutral • Cold

  50. When operating a surface water treatment plant, which of the following laboratory tests is of most significance for establishing chemical dosages for coagulating water?: • pH and alkalinity • Sulfates • Chlorides • Calcium and magnesium • Total hardness

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