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Basic Math Midterm Review

Basic Math Midterm Review. Math for Water Technology MTH 082-2. RULES FOR MIDTERM. DRAW AND LABEL DIAGRAM LIST FORMULAS 3 SOLVE EACH FORMULA INDIVIDUALLY 4. ISOLATE THE PARAMETERS NECESSARY 5. USE YOUR UNITS TO GUIDE YOU 6. SOLVE THE PROBLEM.

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Basic Math Midterm Review

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  1. Basic Math Midterm Review Math for Water Technology MTH 082-2

  2. RULES FOR MIDTERM • DRAW AND LABEL DIAGRAM • LIST FORMULAS • 3 SOLVE EACH FORMULA INDIVIDUALLY • 4. ISOLATE THE PARAMETERS NECESSARY • 5. USE YOUR UNITS TO GUIDE YOU • 6. SOLVE THE PROBLEM

  3. Chlorine ConcentrationsHypochlorite or Available Purity = DIVIDE • Sodium hypochlorite • 5 to 15% available chlorine • 2. Calcium hypochlorite (HTH) • 65-70% available chlorine • 3. Chlorine gas • 100% available chlorine or • 100% active chlorine

  4. % Dry Strength of Solution • Dry chlorine • % Chlorine Strength= Chlorine (lbs) X 100 Solution(lbs) 2. Dry chlorine % Chlorine Strength= Chlorine (lbs) X 100 Water, Lbs + Chlorine(lbs) 3. Dry chlorine % Chlorine Strength= Hypo(lbs)(% available Cl) X 100 100 Water, Lbs+ hypo(lbs) (% available Cl) 100

  5. Dry Hypochlorite Feed Rate • Hypochlorite (lb/day)=lbs/day chlorine • % available chlorine • 100 • 2. Hypochlorite (lb/day)= (mg/L chlorine)(MGD)(8.34) • %strength hypochl • 100 • 3. Hypochlorite (lbs)= (mg/L chlorine)(MG tank Vol)(8.34) • %strength hypochl • 100

  6. % Liquid Strength of Solution • Liquid chlorine • Lbs Cl in liq. hypo= Lbs of chlorine in hypochlorite solution 2. Liquid chlorine (liq. Hypo lbs)(%Strength liq. Hyo) = (hypo Sol lbs) (% Strength liq. hyp) 100 100 3. Liquid chlorine (liq. Hypo gal)(8.34)(%Strength liq. Hyo)=(hypo Sol gal)(8.34)(%Strength liq. Hyp) 100 100

  7. Lbs/dayWhen do you multiply?Available to Active (multiply) Twenty 20poundsof 50% available chlorine equals10 lbs pounds of 100% active chlorine? 20 lbs 20 lbs (0.50)= 10 lbs 10 lbs Active is pure Available is unpure

  8. Lbs/dayWhen do you divide?Active to Available Forty 40poundsof 100% active chlorine (chlorine gas)has the same disinfection power as 61 lbs pounds of 65% available HTH chlorine? 61 lbs 40 lbs 40 lbs = 61 lbs (.65) Active is pure Available is unpure

  9. Lbs/dayWhen do you multiply?Available to Active (multiply) HW #4 Problem 3 Twenty two 22poundsof 65% available chlorine equals14.3 lbs pounds of 100% active chlorine! 22 lbs 22 lbs (0.65)= 14.3 lbs 14.3 lbs Active is pure Available is unpure

  10. Lbs/dayWhen do you multiply?Available to Available (multiply) HW #3 Problem 3 How many pounds of available chlorine are in 2 pounds of 65% powdered dry (available) chlorine? 2 lbs (0.65)= 1.3 lbs 2 lbs of 65% ava 1.3 lbs is available Available is unpure Available is unpure

  11. Lbs/dayWhen do you divide?When do you multiply?PURITY IS THE KEY!!!!! When using hypochlorite, more lbs/day must be used because it is not pure! Hypochlorite is “available” chlorine If you have a certain amount of <100% chlorine (available) and you want to know how much pure (active chlorine) that is you multiply!!!! (Need less of a more pure substance) If you have a certain # of lbs of 100% pure chlorine (active) and what you need is a certain percentage (available) then you divide (its not pure so you will need more of it!)

  12. Chlorine in lbs DOSE in a tank! • Wells are disinfected • Tanks and reservoirs get chlorinated • Pipelines get chlorinated after repair or installation Example 5: A storage tank needs to be disinfected with a 50 mg/L chlorine solution. If the tank holds 70,000 gallons, how many lbs of chlorine gas will be needed? Step 1 Chlorine mg/L to lbs/day formula

  13. Hypochlorite DOSAGE • Calculate lbs/day chlorine • 2. Calculate lbs/day hypochlorite needed by dividing the lbs/day chlorine by the percent available chlorine Example 6: A wastewater flow of 85,000 gpd requires a chlorine dose of 25 mg/L. If sodium hypochlorite (15% available chlorine) is used, how many lbs/day of sodium hypochlorite are required? How many gal/day is this? Step 2 Calculate lbs/day sodium hypochlorite (1180 lbs/d)/(8.34 lbs/gal)= 141 gal/day sodium hypochlorite

  14. Determining Cl Concentrations from Hypochlorite dosage • Disinfection requires 280 lb/day chlorine. If CaOCl • (65% available Cl) is used how many lbs day are required (%concentration)(X lb/day)= total lbs/day required Rearrange: (X lb /day) = Total lbs/d = (280 lbs) = 430.77 lb/d CaOCL % concentration (.65)

  15. Solutions with Specific Gravity • How many pounds of available chlorine are in 5 gallons of 12% hypochlorite solution if its specific gravity is 1.19? Lb=(% concentration) X (Specific gravity) X (lb/gal) X (gal) Lb= (.12) X (1.19) X (8.34 lb/gal) X (5 gal) Lb=5.95 lb Calcium hypochlorite, gal= (lb CaOCl2 @ 100%)/(8.34 lb/gal)(CaOCl2 %) Calcium hypochlorite, lbs= (gal CaOCl2)(8.34 lb/gal)(62.5%)/(100%)

  16. Hypochlorite Solutions is disinfected with 62.5% calcium hypochlorite solution, If 3.03 gal of CaOCl2 were used, what must have been the dosage of the calcium hypochlorite? Assume the calcium hypochlorite weighs 8.34 lb/gal. Get answer in (lbs) to solve for dosage in lbs formula! Calcium hypochlorite, lbs= (gal CaOCl2)(8.34 lb/gal)( % Available) (100%) Calcium hypochlorite, lbs= (3.03 gal CaOCl2)(8.34 lb/gal)(.625) Calcium hypochlorite, lbs= 15.79 lbs Solve lbs formula  Number of lb=(MG)(Dosage)(8.34 lb/gal)  Dosage mg/L CaOCl2=15.79 lbs CaOCl2/(0.038MG)(8.34 lb/gal)

  17. Calcium Hypochlorite Solutions Midterm 3. storage tank requires disinfection with a 65% calcium hypochlorite solution.  How many gallons of hypochlorite solution are required if the desired dose is 50.0 mg/L.  Assume the calcium hypochlorite solution weighs 10.21 lb/gal.?   Calcium hypochlorite, gal= (lb CaOCl2 @ 100%) (10.21 lb/gal)(CaOCl2 % available) Calcium hypochlorite, gal= (51.7 lb CaOCl2) = 7.79 gal (10.21 lb/gal)(.65)

  18. Specific Gravity, LBS, Gallons, Solution Strength

  19. Problem #1 • Determine the chlorinator setting (lbs/day) needed to treat a flow of 3.2 MGD with a chlorine dose of 1.7 mg/L (5 pts).

  20. Problem #2 2. The chorine demand was calculated to be 11 lb/day, and the residual was measured at 0.5 mg/L. What was the chlorine dose (lbs) that day, if the flow was 1.2 MGD?

  21. Volume= 0.785(diameter2)(depth) • Volume= 0.785(25ft)2(5 ft) • Volume=2453ft3 • Conversion= 2453 ft3 (7.48 gal/1ft3) • Conversion=18349 gallons • Conversion=.018349 MG Problem #3 3. How many gallons of 15% liquid chorine (s.g. = 1.2) would be required to dose a circular tank to a 50 mg/L concentration? The tank diameter is 25 ft. and the water depth in the tank is 5 ft. ? Gallons 1.2 SG 15% OCl 5 ft 25 ft

  22. Problem #4 4. A barrel contains 30 gallons of 12% liquid hypochlorite at a specific gravity of 1.19. How many pounds of dry HTH (65% active hypochlorite) would be needed to replace the chlorine in the barrel? (%concentration)(X lb)= total lbs required X lb= 35.72 lbs/.65 X=54.96 lbs of 65% HTH The lbs/day formula calculates the pure concentration of chlorine within a % solution of chlorine. Thus in the 12% hypochlorite solution there are 35 lbs of pure Cl (A). Imagine the same size barrel of a higher concentration of OCl- as 65% HTH (B). Which solution has more lbs of pure Cl2? Well, the 65% it’s a more concentrated solution so there will be more pure chlorine in it. 1.19 SG 12% OCl= 35 lbs pure Cl2 65% OCl as HTH 55 lbs pure Cl2 A B

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