Q5) Paper pulp sludge having a concentration 800 mg l^-1 and volumetric flow rate of 4 litre s^-1 is to be thickened in a pressurised recycle dissolved air process. Bench tests show that if the saturator is run at 4 atmospheres then the water is 85% saturated with air and a air solids mass ratio of 0.01 is necessary for efficient operation of the DAF unit. What is recycle ratio and Recylce flow rate (Q_r) (Ans R= 13.8%, Qr= 0.555 litre s^-1)

Assume that Henrys Law coefficient is 24 mg l^-1 atm^-1