What should be the setting on the liquid alum chemical feeder in milliliters per minute when the flow is 2.5 MGD?
Liquid alum delivered to a water treatment plant contains 485 milligrams of alum per milliliter of liquid solution with specific gravity of 1.325. Jar testes indicate that the best alum dose is 9 mg/L. There is 3.785 in one gallon.
A. 74 mL/min B. 81 mL/min C. 92 mL/min D. 103 mL/min E. 118 mL/min
92mL/min, 92.0297 There are two difficult aspects to this problem, specific gravity, and the percentage ofalum in the solution. Math Constant: Specific gravity of water = 1 Math Constant: 1 gram of water = 1mL Math Constant: There are 1000 grams of water in one liter, and one milligram is one thousandth of a gram, so one milligram per liter (mg/L) is one millionth of a liter Math Constant: 1,440 minutes in one day Math Constant: 1 gallon = 3.785 liters Step 1: 2.5mgd x 3.785 = 9.4625 million liters, 1 milligram is one millionth of a liter so 9.4625 liters is 1mg/L of 9.4625 million liters Step 2: We need 9mg/L so, 9.4625 x 9 = 85.1625 liters of solution Step 3: The liquid alum contains only 485 milligrams per milliliter. This is like saying it contains 485 parts alumout of 1000, or that it contains 48.5% alum. Because our solution is less than 100% we need to divide our needed amount by the percentage of the solution. So, 85.1625 / 48.5% = 175.59278 liters of a 48.5% solution needed. Step 4: The liquid alum has a higher specific gravity (heavier per gallon) than water so we need less of it. 175.59278 / 1.325 = 132.52285 liters ofliquid alum per day needed Step 5: 1,440 minutes in one day so 132.52285 / 1440 = 0.0920297 liters per minute needed Step 6: 1,000 milliliters in 1 liter, so 0.0920297 x 1000 = 92.0297 mL/min I hope that helped :)