4.33. A stream containing 5.15 wt % chromium, Cr, is contained in the wastewater from a metal finishing plant. The wastewater stream is fed to a treatment unit that removes 95% of the chromium in the...

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Extracted text: 4.33. A stream containing 5.15 wt % chromium, Cr, is contained in the wastewater from a metal finishing plant. The wastewater stream is fed to a treatment unit that removes 95% of the chromium in the feed and recycles it to the plant. The residual liquid stream leaving the treatment unit is sent to a waste lagoon. The treatment unit has a maximum capacity of 4500 kg wastewater/h. If wastewater leaves the finishing plant at a rate higher than the capacity of the treatment unit, the excess (anything above 4500 kg/h) bypasses the unit and combines with the residual liquid leaving the unit, and the combined stream goes to the waste lagoon. m(kg Cr/h) Ino water] 95% of Cr in feed to unit Wastewater mt ke/h) s 4500 kgn 0.0515 kg Cr/kg (48F To waste lagoon (a) Without assuming a basis of calculation, draw and label a flowchart of the process (b) Wastewater leaves the finishing plant at a rate m = 6000 kg/h. Calculate the flow rate of liquid to the waste lagoon, rm(kg/h), and the mass fraction of Cr in this liquid, x6(kg Cr/kg). (c) Calculate the flow rate of liquid to the waste lagoon and the mass fraction of Cr in this liquid for in, varying from 1000 kg/h to 10,000 kg/h in 1000 kg/h increments. Generate a plot of xe versus m. (Suggestion: Use a spreadsheet for these calculations.) (d) The company has hired you as a consultant to help them determine whether or not to add capac- ity to the treatment unit to increase the recovery of chromium. What would you need to know to make this determination?