Reverse Osmosis Flashcards
What is osmosis?
The diffusion of water across a semi-permeable membrane from a low solute concentration to a high solute concentration
Osmosis aims to balance solute concentrations on either side of the membrane.
What is reverse osmosis?
Applying pressure to overcome osmotic pressure and concentrate solutes
Reverse osmosis requires sufficient pressure on the concentrated side.
What is the typical membrane pore size in reverse osmosis?
As small as 0.0001μm
This small size allows for the filtration of most dissolved ions and molecules.
What percentage of dissolved minerals does reverse osmosis typically remove?
More than 98%
Significant pressures of 10 to 20 bar are required for this removal.
What are the two water streams produced in reverse osmosis?
Permeate and concentrate
Permeate is the filtered water, while concentrate is the contaminated water.
What is the purpose of pumping feed water at high pressure in reverse osmosis?
To overcome osmotic pressure
This allows water molecules to pass through the membrane.
What happens to minerals during the reverse osmosis process?
They remain in the reject stream or concentrate
The concentrate can be sent to drain or returned to the feed water supply.
What are the advantages of reverse osmosis?
Removes alkalinity and problem compounds, provides blanket removal of dissolved or suspended substances
These advantages enhance water quality.
What are some disadvantages of reverse osmosis?
Difficult concentrate disposal, high reject rate, expensive membrane replacement
The reject rate can be around 25% of feed water volume.
What is recommended before using reverse osmosis for hard feed water?
An ion exchange unit
This reduces the load on RO membranes and prevents fouling.
What is the role of anti-scalent dosing in reverse osmosis?
To prevent silica and hardness scale blocking membranes
This helps maintain membrane efficiency.
Why is an activated carbon filter required before reverse osmosis?
To remove chlorine that can damage membranes
Chlorine is harmful to the integrity of RO membranes.
What is the main advantage of reverse osmosis?
Converts feed water to virtually pure water
This allows precise adjustment of water composition for specific requirements.
Fill in the blank: Reverse osmosis enables brewers to adjust water composition to achieve _______.
Any water specification required
This flexibility is crucial for brewing processes.
