A 283-m3(10,000 ft3) basin is to be aerated with six spargers, each sparger using air at the rate of 7:08 × 10-3 m2/s. If 283 K wastewater, initially containing a dissolved oxygen level of 5×10-3 mmol/L and filling the basin to a depth of 4.55 m, is aerated for 9000 s, evaluate the final dissolved oxygen level.
The dissolved solids content will be low enough so that Henry's law will be obeyed, with a Henry's law constant of 3:27 × 104 atm/mole fraction.