Published by Carlos Edmundo Sandoval Ayala, ESE & ZETA CIA. LTDA. - Responsable de Proyectos
Your first selection criteria would be to determine the quality requirements of the end products, principally in terms of hardness and sodium. NF is also called the softening membrane process because it preferentially removes CA and MG hardness (>90%) but removes NA and CL at 50%. RO removes all ionic constituents at >90-98%. That's why RO membranes are generally more expensive than NF membranes and you should select NF is it meets your quality requirements without an overkill. I think you get the picture.
Published by Mohamad Amin Saad, MASAR Technologies, Inc. - President & Prinicipal Consultant & Trainer
Before you can answer this, you need to know what the water quality is. This will allow the manufacturers of NF and RO design the system to your expectations and water quality. You will need to use a certified water quality lab. This data can be sent to the manufacturers. Let me know if I can be f further assistance.
Published by Benjamin Head
I agree with Prof Junfeng but also agree with Prof John, Prof Peter, it depends on raw water in and the final quality you want.
Published by AGGASIT DAD, Energy and Environmental including CDM and Innovation Project Consultant Freelancer
We three agree! Your choice will be dependent on water quality required. Operation and cost will be similar. NF operation could be slightly lower due to lower energy requirements. Generally speaking RO will meet NF requirements, however, NF will not meet RO requirements.
Published by John Herring
Of course, an important consideration is the relative concentrations of mono and multivalent ions in the feedwater. Most RO membrane manufacturers make NF membranes, but their properties vary with regard to the specific rejection of multivalent ions and passage of monovalent ions.
Published by Peter Cartwright, President at Cartwright Consulting Co.
NF and RO removes different contaminants from raw water, and Junfeng is right. the choice will depend on what is your final water quality requirement.
Published by Peter E. De Dios, Senior Staff-Base Built Team, Facility Engineering at Sunpower Philippines Manufacturing Ltd.
Hi Carlos,
the NF and RO filtration capabilities are rather different.
NF is mostly used to reject divalent ions while RO are used to reject both divalent and singly charged ions.
Depending on what is your ultimate treatment goals - the choice of technology between the two should be very clear for specific cases.
Filtration Spectrum Chart
https://www.units-of-measure.com/2019/06/osmonics-filtration-spectrum-chart.html
Regards,
Junfeng
Published by Junfeng Kok, Principal Process Engineer at Hyflux