1. Pounds Formula Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit

2. 1. Loading on treatment system. CALCULATION OF POUNDS We often need to know how many pounds of material we are dealing with. 2. Calculating pounds of a chemical to add. 3. Calculating pounds of a material being discharged.

3. Pounds Formula FormulaFormula Pounds FF oooo rrrr mmmm uuuu llll aaaa mg/L (Metric) To Pounds (English)

4. CALCULATION OF POUNDS 1. The Quantity of water must be known. (The flow of the water stream or the volume of the tank containing the water.) Three things must be known to calculate the POUNDS of material in a quantity of water. 2. The Concentration of material in water must be known. (Lab analysis) 3. The Weight of a gallon of water The Weight of a gallon of water is a constant. 1 gallon of water weighs 8.34 pounds

5. Pounds = CALCULATION OF POUNDS Concentration Of STUFF In the Water Conc. x Flow (or Volume) x 8.34 Lbs/gallon X Quantity Of Water The STUFF Is In Weight Of The Water X

6. Flow (volume) and concentration must be expressed in specific units. Flow or Volume must be expressed as millions of gallons: = MG i.e.) A tank contains 1,125,000 gallons of water. How many million gallons are there? 1,125,000 gal = 1.125 MG 1,000,000 gal/MG 1,000,000 gal/MG gallons

7. Concentration must be expressed as parts per million parts. Concentration usually reported as milligrams per liter. This unit is equivalent to ppm. 1 mg = 1 mg = 1 mg = ppm liter 1000 grams 1,000,000 mg ppm = Parts Mil Parts = Lbs. Mil Lbs. mg/L =

8. Lbs. = When Flow (volume) is expressed as MG and Concentration is in ppm, the units cancel to leave only pounds. Concentration x Flow (or Volume) x 8.34 Lbs/gallon Lbs. M Lbs. XX M gal Lbs. gal = Lbs.

9. If we enter flow rate in M gal per day (MGD), the answer will be in Lbs/day. Lbs. M Lbs. XX M gal Lbs. gal Lbs./Day = Concentration (mg/L) x Flow (MGD) x 8.34 Lbs/gal. Day = Lbs./Day

10. EXAMPLE POUNDS CALCULATIONS = 150 Lbs./day Suspended Solids Calculate the POUNDS of suspended solids discharged to the receiving stream if the suspended solids concentration was 15 mg/L and the plant flow was 1.2 MGD. 1. POUNDS/day = 15 mg/L X 1.2 MGD X 8.34 #/gal POUNDS/day = Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon

11. = 3.1 Lbs./day Phosphorus Calculate the POUNDS of Phosphorus discharged from a system if the Phosphorus concentration was 0.75 mg/L and the flow was 500,000 gallons/day. 2. POUNDS/day = 0.75 mg/LX 500,000 gal/day X 8.34 #/gal POUNDS/day = Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon 1,000,000 = 0.75 mg/L X 0.50 MGD X 8.34 #/gallon

12. Calculate the POUNDS of Mixed Liquor Volatile Suspended Solids, (MLVSS) in a 250,000 gallon aeration tank if the MLVSS concentration is 2500 mg/L. 3. POUNDS = Conc. (mg/L) X Flow (MG) X 8.34 pounds/gallon

13. = 5200 Lbs MLVSS Calculate the POUNDS of Mixed Liquor Volatile Suspended Solids, (MLVSS) in a 250,000 gallon aeration tank if the MLVSS concentration is 2500 mg/L. 3. POUNDS = 2500 mg/L X 250,000 gallons X 8.34 #/gal POUNDS = Conc. (mg/L) X Q (MG) X 8.34 pounds/gallon 1,000,000 = 2500 mg/L X 0.25 MG X 8.34 #/gallon

14. The Pounds formula can be rearranged to calculate flow or concentration: a.M gal = Lbs _ 8.34 Lbs/gal x conc. (mg/L) b.conc. (mg/L) = Lbs _ 8.34 Lbs/gal x M gal. What volume may be discharged to meet a pounds limit? What is the concentration if this amount of chemical was added?

15. Pounds = CALCULATION OF POUNDS Concentration Of STUFF In the Water Conc. x Flow (or Volume) x 8.34 Lbs/gallon X Quantity Of Water The STUFF Is In Weight Of The Water X

16. 1. Calculate the POUNDS of suspended solids discharged to the receiving stream if the suspended solids concentration was 18 mg/L and the plant flow was 0.20 MGD. Practice Problems 2. Calculate the POUNDS of BOD going to a treatment system if the influent BOD concentration was 195 mg/L and the flow was 86,000 gallons/day. 3. Calculate the CONCENTRATION of Alum added if 43 pounds were fed into a flow of 0.125 MGD. 4. Calculate the number of GALLONS that may be discharged per day from a lagoon if the permit limit is 30 pounds of BOD per day and the BOD concentration is 20 mg/L. Work Calculations on Separate Paper Answers Given on Next Slides

17. POUNDS CALCULATIONS = 30 Lbs./day Suspended Solids POUNDS/day = Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon Calculate the POUNDS of suspended solids discharged to the receiving stream if the suspended solids concentration was 18 mg/L and the plant flow was 0.20 MGD. 1. POUNDS/day = 18 mg/L X 0.20 MGD X 8.34 #/gal Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon

18. = 140 Lbs./day BOD Calculate the POUNDS of BOD going to a treatment system if the influent BOD concentration was 195 mg/L and the flow was 86,000 gallons/day. 2. POUNDS/day = 195 mg/L X 86,000 gal/day X 8.34 #/gal Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon 1,000,000 = 195 mg/L X 0.086 MGD X 8.34 #/gallon

19. = 41.25 mg/L Alum Calculate the CONCENTRATION of Alum added if 43 pounds were fed into a flow of 0.125 MGD. 3. 43 #/day = Conc. (mg/L) X 0.125 MGD X 8.34 #/gal POUNDS/day = Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon 0.125 X 8.34 43 0.1325 X 8.34 = Conc. (mg/L)

20. 0.18 = Flow Calculate the number of GALLONS that may be discharged per day from a lagoon if the permit limit is 30 pounds of BOD per day and the BOD concentration is 20 mg/L. 4. POUNDS/day = 30 #/day = 20 mg/L X Flow MGD X 8.34 #/gal Conc. (mg/L) X Flow (MGD) X 8.34 pounds/gallon 20 mg/L X 8.34 #/gal 20 X 8.34 30 20 X 8.34 Flow MGD 0.18 MGD X 1,000,000 = 180,000 gallons/day MGD =

21. Pounds Formula Prepared By Michigan Department of Environmental Quality Operator Training and Certification Unit