PAC 1 Exam with Questions with complete solutions

PAC 1 Exam with Questions with complete solutions Most water sources are classified as: a) Clean or dirty b) Hot or cold c) Surface or well d) Acidic or alkaline - ✔✔c) Surface or well Fe++, Mg++ are known as: a) divalent anions b) divalent cations c) reactive atoms d) molecu les - ✔✔b) divalent cations How many pounds of product are needed to make 300 gallons of a 1% solution (weight to weight) of an Ondeo Nalco product that has a density of 9.4#/gal? a) 22.1 b) 25 c) 28.2 d) 235 - ✔✔b) 25 300 gallons is 2,502 pounds of water. 1% would be 25 pounds. Because you are working in pounds, no further conversions are necessary. 25 pounds weight of product to weight of water . If it was volume product to volume of water the answer would be 28.2 because 1% of 300 gallons is 3 gallons an d 3 X 9.4 = 28.2 What is the rise rate of a clarifier with the following dimensions? Clarifier diameter: 30 ft Clarifier depth: 12 ft Flow: 1.0 million gallons per day Clarifier type: Upflow raw water clarifier Effluent type: Plant process water Centerwell diameter: 10 ft a.) 31,800 gpm/ft2 b.) 10.7 gpm/ft2 c.) 1.10 gpm/ft2 d.) Insufficient information to determine - ✔✔c.) 1.10 gpm/ft2 Surface Rise Rate = Q/A Where: Q = inflow, gpd or gpm A = surface area of clarifier, ft2 The area of the settling basin is equal to the surface area of the clarifier minus the surface area inside the mixing drum or center well. 1 mgd/1440 min/day = 694 gpm Surface Area = pi r2 A Clarifier = 3.14 X (15' X 15') = 706.5 sq ft A Centerwell = 3.14 X (5 X 5) = 78.5 sq ft Therefore, the rise rate is 694/(706.5 -78.5) = 1.10 gpm/ft2 The source of color in most surface waters is: a.) Industrial waste b.) Lignins and Tannins c.) Paper Mill Discharge d.) Micro -organism growth - ✔✔b.) Lignins and Ta nnins Recirculated sludge aids in clarification by: a.) "Sweeping" coagulated particles out of the water b.) Providing alkalinity to the process c.) Keeping fluid and not plugging the blowdown line. d.) Preventing carryover of floc particles. - ✔✔a.) "Sweeping" coagulated particles out of the water