To remove the solution containing metal from a part after metal plating, the part is commonly rinsed with

water. This rinse water becomes contaminated with metal and must be treated before being discharged.

Figure A shows a typical rinse process for a nickel plating operation. The concentration in the plating tank

is $85$ g$/$L of nickel, and the parts $$drag out$$ plating solution from the bath at a rate of $0\mathrm{.}05$ L$/$min$.$ What

flow rate of clean water is needed in the rinse tank if the maximum allowable concentration of rinse water

is $20$ mg$/$L$?$