Lesson 3 - Water SAQ
This lesson allows you to test yourself on the material covered in the Water lesson and determine the level to which you have met the learning outcomes.
Suggested Response - Q7
** Compare crossflow and dead-end filtration:
a) Draw a basic sketch showing how this works. Be sure to show the feed and the filtrate as well as the concentrate if required.
b) Explain the different processes.
c) What are their main advantages and disadvantages?
Response:
a)
Figure: Crossflow and dead-end filtration
b) In dead-end operation the particles accumulate in the filter, whilst with crossflow filtration they are constantly removed into a concentrate stream.
c) With crossflow filtration the process can run for longer, as the particles remain in the concentrate and do not foul the membrane as easily. However, this has limitations, as you have to deal with a concentrate stream.
With dead-end flow the membranes fill up, resulting in an increase in pressure and the need to backflush. However, no concentrate stream and recirculation equipment is required.