Problem 1: DAF Design
A wastestream from a petrochemical industry has a flow of 0.95 m3/min (250 gal/min) and a temperature of 39.4 oC (103 oF). The concentration of emulsified oil and the suspended solids in the wastestream is 250 mg/L. An effluent concentration of 20 mg/L of emulsified oil and suspended solids is required. Laboratory study showed:
Optimum alum dose: 30 mg/L
Optimum A/S ratio: 0.04 mL/mg
Surface loading rate: 0.081 m3/min.m2 (2 gal/min.ft2) Operating pressure: 4.4 atm gage (65 lb/in2 gage) Sludge production: 0.64 mg/mg of alum
Fraction of air dissolved: 0.80
Solubility of air at 39.4 oC (103 oF): 19 mL/mg
Calculate
i) The recycle rate.
ii) The Surface area of flotation unit.
iii) The volume of sludge produced if the sludge concentration is 3 percent by weight.
Problem 1: DAF Design
A wastestream from a petrochemical industry has a flow of 0.95 m3/min (250 gal/min) and a temperature of 39.4 oC (103 oF). The concentration of emulsified oil and the suspended solids in the wastestream is 250 mg/L. An effluent concentration of 20 mg/L of emulsified oil and suspended solids is required. Laboratory study showed:
Optimum alum dose: 30 mg/L
Optimum A/S ratio: 0.04 mL/mg
Surface loading rate: 0.081 m3/min.m2 (2 gal/min.ft2) Operating pressure: 4.4 atm gage (65 lb/in2 gage) Sludge production: 0.64 mg/mg of alum
Fraction of air dissolved: 0.80
Solubility of air at 39.4 oC (103 oF): 19 mL/mg
Calculate
i) The recycle rate.
ii) The Surface area of flotation unit.
iii) The volume of sludge produced if the sludge concentration is 3 percent by weight.
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