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Q) What is the permeate flow produced by the RO array? Wastewater containing 280

ID: 1714788 • Letter: Q

Question

Q) What is the permeate flow produced by the RO array?

Wastewater containing 280 mg/L BOD with a pH of 7.9 is being pumped at a rate of 450 m^3/h via a pipe to a biological treatment.

After a biological treatment of water. The treated water then passes through 15 cylindrical sand filters operating at a pressure of 0.17 bar for the clean filter, the mean sand grain size being 700 m, and the bed porosity 32% with an aspect ratio of 0.8.

The filtered water then passes through 2 stages of reverse osmosis modules, each providing a conversion of 45%.

Finally, the water passes through a degasser to strip the CO2 from the water.

Explanation / Answer

Answer:

Permeate flow is the measure of Reverse Osmosis performance. It can also be denoted as the portion of feedwater which passes through the membrane.

"Permeate = Feedwater - Concentrate"

So in simple terms,

Feed water = 450 cum/hr.

Conversion ratio = 45%.

So, the premeate flow after 2 stages of RO modules @ 45% conversion = 450*45% = 202.5*45% = 91.125%

Terminologies:

Aspect ratio: The ratio of width to the height of the screen