front 1 The capacity to neutralize acids is called? | back 1 Alkalinity. |
front 2 The amount of acid that is added to water (liquid) to lower the pH to 4.5 determines what parameter? | back 2 Alkalinity |
front 3 Water with a hardness of more than a 100 mg/L is called? | back 3 Hard Water |
front 4 Total hardness is the sum of what salts? | back 4 Calcium and Magnesium |
front 5 Calcium and magnesium are defined as what type of hardness? | back 5 Carbonate Hardness |
front 6 Carbonate Hardness is called? | back 6 Temporary Hardness because it is easy to remove |
front 7 If the Total Hardness of the water is less than the alkalinity, what kind of hardness is present in the water? | back 7 Carbonate Hardness |
front 8 The total hardness is greater than the alkalinity. Subtracting the alkalinity from the hardness gives you what type of hardness? | back 8 Noncarbonate Hardness |
front 9 Noncarbonate hardness is called? | back 9 Permanent Hardness because it is difficult to remove |
front 10 The alkalinity in question 8 is equal to what type of hardness? | back 10 Carbonate Hardness |
front 11 Total Hardness is the sum of what 2 types of hardness? | back 11 Ans. Carbonate and Noncarbonate Hardness |
front 12 A pure substance composed of 2 or more elements whose composition is constant is called? | back 12 A Compound |
front 13 CaO is the shorthand symbol for what substance? | back 13 Lime or Quicklime |
front 14 (Ca(OH)₂) is the formula for what chemical? | back 14 Slaked Lime or Hydrated Lime |
front 15 What is the first reaction that takes place when you add slaked lime to raw water? | back 15 Carbon Dioxide (CO₂) is removed. |
front 16 What is a byproduct of slaking lime? | back 16 Heat |
front 17 What is the simplest test to determine if water is hard? | back 17 Soap |
front 18 Why do we soften water? | back 18 Ans. Hard water causes scaling of boilers and chillers |
front 19 What is added to lime softening to remove noncarbonate hardness? | back 19 Soda Ash (Na₂CO₃) |
front 20 What is Methyl Orange Alkalinity? | back 20 Total Alkalinity |
front 21 What happens when lime is added to water? | back 21 Lime raises the pH and Alkalinity |
front 22 When lime raises the water pH to 10, what reaction takes place? | back 22 Soluble calcium forms insoluble precipitates |
front 23 When lime raises the pH to 11 or higher, what reaction takes place? | back 23 Magnesium Hydroxide (magnesium hardness) precipitates form |
front 24 What is the SMCL for pH? | back 24 6.5-8.5 |
front 25 What method is used to lower the pH? | back 25 Ans. Recarbonation |
front 26 Water treatment plants have to add excess lime to remove magnesium hardness. What treatment method is used to lower the cost by reducing the amount of lime added to remove magnesium? | back 26 Split Treatment |
front 27 Why must we lower the pH of the water after lime has formed hardness precipitates? | back 27 Ans. To reduce the scaling tendencies of water |
front 28 How is pin floc removed during water treatment? | back 28 Ans. Recarbonation |
front 29 When you use 0.02N Sulfuric Acid to titrate a water sample to a pH of 8.3, what parameter is being measured? | back 29 P Alkalinity (Phenolphthalein Alkalinity) |
front 30 When you use 0.02N Sulfuric Acid to titrate a water sample to a pH of 4.5, what parameter is being measured? | back 30 Total Alkalinity or Methyl Orange Alkalinity |
front 31 What does NPDES mean? | back 31 National Pollutant Discharge Elimination System |
front 32 What causes carbonate hardness? | back 32 Alkalinity |
front 33 What causes Noncarbonate Hardness? | back 33 Sulfates |
front 34 What is the SMCL for sulfates? | back 34 250 mg/L |
front 35 Why are water treatment plant operators concerned with sulfates? | back 35 Ans. They have a laxative effect |
front 36 Below a water pH of 8.3, what type of alkalinity is always absent? | back 36 P Alkalinity (PA) |
front 37 What is a common problem found in home water heaters that use a lime softened water? | back 37 Scaling of the water heaters heating elements because calcium carbonate is not stable in hot water |
front 38 Which of the following are advantages of lime softening? | back 38 A. Corrosion control B. Iron and manganese removal C. Disinfection due to high pH D. Taste and odor reductions E. Removal of radioactivity F. All of the above Note: They may not give you a, B, C, D as choices. They will likely give you only E. |
front 39 All water treatment plants must use what book to determine the method of analysis for any parameter the WTP is required to analyze for? | back 39 Standard Methods for Examination of Water and Wastewater STANDARD IN TESTING |
front 40 What test is used to measure the intensity of the basic or acidic condition of water? | back 40 pH |
front 41 What test is used to measure the hydrogen ion activity in a liquid? | back 41 pH |
front 42 What is the numerical range of pH? | back 42 0 to 14 |
front 43 The logarithm (base 10) of the reciprocal of the hydrogen ion activity is called? | back 43 pH |
front 44 When Alum is added to the water, what happens to the pH? | back 44 pH goes down |
front 45 When the amount of Alum is decreased during treatment, what adjustment is usually made to the lime dosage? | back 45 Lime dosage is also decreased |
front 46 When the amount of Alum is increased during treatment, what adjustment is usually made to the lime dosage? | back 46 Lime dosage is also increased |
front 47 Below a pH of 8.3 what is the only alkalinity usually present in water? | back 47 Bicarbonate alkalinity CARBON DIOXIDE |
front 48 What is the formula for hydroxide alkalinity (OH)? | back 48 2P-T |
front 49 If the PA is 84 and the TA (Total Alkalinity is 160), what is the OH? | back 49 8 (2 x 84 (PA)-160 (TA)=8 |
front 50 In question 49, If the PA is 84 and the TA (Total Alkalinity is 160), what is the OH? what adjustment must be made to the lime dosage? | back 50 Lower the lime dosage |
front 51 Adding the bicarbonate, carbonate, and hydroxide alkalinity gives you what result? | back 51 Total Alkalinity |
front 52 Below a pH of 4.5, what is usually present in the water? | back 52 Carbon Dioxide (CO₂) and no alkalinity |
front 53 When lime is added to water, bicarbonate alkalinity is converted to? | back 53 Carbonate alkalinity which allows the calcium to precipitate as calcium Carbonate (CaCO₃) |
front 54 When excess lime is added to water, PA is converted to? | back 54 OH (Hydroxide) which allows magnesium to precipitate |
front 55 Lime softening alone can reduce water hardness to what level? | back 55 30-40 mg/L |
front 56 During recarbonation what is added to the water to lower the pH and alkalinity? | back 56 Carbon Dioxide (CO₂) |
front 57 Carbon Dioxide (CO₂) is added where during the recarbonation process? | back 57 Before filtration |
front 58 In split treatment, how much raw water is bypassed? | back 58 20% |
front 59 What happens to the pH when sodium aluminate is used as a coagulant? | back 59 pH goes up |
front 60 If sodium aluminate is substituted for Alum, what will happen to the lime dosage? | back 60 Lime dosage will be decreased |
front 61 What is used to reduce the pH and alkalinity in treated water? | back 61 Carbon Dioxide (CO₂) |
front 62 What 2 chemicals should not be added to the same conveyer belt? | back 62 Lime and Alum (explosive combination) |
front 63 What is a disadvantage of recirculating sludge? | back 63 Magnesium content of water increase |
front 64 Where is lime sludge disposed of? | back 64 Sanitary Landfill |
front 65 Large amounts of what chemical in lime sludge makes it difficult to dewater? | back 65 Magnesium-(less than 2 to 1 ratio of Ca to Mg is difficult to dewater) |