Question

solve 3-2 based on answers 3-1

correct answers should be:

3-1 a. 20 mg/L b. 50 mg/L

3-2 a. sodium carbonate 645 tons/yr, $161,000 per yer

3-2 b. lime 341 tons/yr $17000

3-1 Calculate the decrease in alkalinity when using the following coagulant doses: a) alum = 40 mg/L and, b) ferric chloride = 50 mg/L 3-2 If the above ferric chloride addition is for phosphorous reduction at a wastewater plant with a flow rate of 8 MGD. Look up the unit costs of calcium carbonate and lime and calculate the costs of adding the alkalinity using a) sodium carbonate b) lime

Answer 1

1a) A12(SO4)3.14 H2O + 6 H cong = 2Al(OH), v + 6CO₂ + 14H₂O + 304" 594mg Alum consumes 366 ming HCO3" 400g Alum consumer 366 x 40mg HLOE 594 = 24.646mg Alkalinity wi mg/Las Salaz = 24.646X50 - 20.2 mg 1L x 20 mg/L alkalinty

16 2 FeCl3 + 3 Ca(HCO3)2 → 2 Fe(OH)₂ + 36ack +6CO2 162.5g of terrie chloride - consumes 1839 of flecom 50g of terrie chloride consumes 183 x 50 162.5 56.30 mgle Alkalinity in mgle as call: 56.30 X 50 = 46.15 mgle

For 3b I require the price of sodium carbonate and lime.

Thank you