# Process Calculations GATE-2013

###### Common data for Q 1 & 2:

A reverse osmosis unit treats feed water (F) containing fluoride and its output consists of a permeate stream (P) and a reject stream (R). Let C_{F}, C_{P}, and C_{R} denote the fluoride concentrations in the feed, permeate, and reject streams, respectively. Under steady-state conditions, the volumetric flow rate of the reject is 60 % of the volumetric flow rate of the inlet stream, and C_{F} = 2 mg/L and C_{P} = 0.1 mg/L.

**Q 1:** The value of C_{R} in mg/L, up to one digit after the decimal point, is ___________.

**Q 2:** A fraction *f* of the feed is bypassed and mixed with the permeate to obtain treated water having a fluoride concentration of 1 mg/L. Here also the flow rate of the reject stream is 60 % of the flow rate entering the reverse osmosis unit (after the bypass). The value of *f*, up to 2 digits after the decimal point, is ____________.