P7.37 The antibiotic streptomycin is extracted from a fer-

mentation broth using an organic solvent, where KD =

40 (g streptomycin/kg extract/g streptomycin/kg raffi-

nate). If the broth contains 1 wt% streptomycin and is

fed at 150 kg/min to the solvent extraction unit, what

is the required solvent flow rate to recover 80% of the

streptomycin?