NSTM 531 DESALINATION, VOL 3 R/O DESALINATION PLANTS

Question 1

What are the 3 differences between RO and conventional filtration process?

Answer 1

• Osmotic Pressure
• Crossflow Operation
• Particular Size

Question 2

What is the RO process?

Answer 2

Pressurized seawater is passed over a semipermeable membrane that passes pure water but excludes salt species.

Question 3

For seawater RO, an ______ ______ of 350 to 400 pounds per square inch (psi) exists across the membrane, requiring fairly high pressures (700 to 1000 psi) of operation.

Answer 3

Osmotic Pressure

Question 4

Conventional filtration processes typically operate from _______.

Answer 4

10 to 25 psi

Question 5

In the RO process, the process fluid passes over the membrane, but only a small
portion of ________ passes directly through it.

Answer 5

20 to 30 percent

Question 6

What happens to the salt that remains in the concentrating feed solution during the RO process?

Answer 6

It is Discharged Overboard

Question 7

Why was the term Reverse Osmosis developed?

Answer 7

Because the process is often thought of as the reverse of the natural process of osmosis.

Question 8

If the weaker solution is pure water (solvent) and the concentrated solution is seawater, the resulting
osmotic pressure will be about _______.

Answer 8

350 psi

Question 9

In the process of R/O, a pressure of
_______ is required to obtain an acceptable flow of water through the membrane.

Answer 9

700 to 1000 psi

Question 10

This theory proposes that the water and salt are dissolved directly into the membrane
from the saline water side.

Answer 10

Solution-Diffusion Theory