Help me in RO plant design calculations 2

[Asisraja D]

Hello Professionals
I am working as a project engineer and we have planned to design an RO (Reverse Osmosis) plant for our plant and we have got data sheet from our vendor who gave us some details for the service flow rate 2000 lph and feed flow rate for RO module is 1000 lph but the final outlet is 250lph with 50-55% of recovery. here i have some doubts in this.

1.) How do we decide recovery percentage % for this ?
2.) What are the parameters should i have to consider to design an RO plant ?
3.) Does recovery percentage % change over the period of time ?

Please bear me because i am new to water system so give me an idea or calculation manuals for me.

Thanks to all.

I have attached the vendor documents & conceptual Flow diagram of the RO plant.

 

[Asisraja D]

Vendor data sheet for your reference

 

[bimr]

Your system is so small that it will be limited to commercially available equipment, not something that is custom made for your application.

The most important parameter is the water quality which you have not provided.

Typical recovery is 50% per membrane. The vendor has quoted you a system with a single membrane. If you take the brine effluent from the first membrane and pass it through a second membrane, then you have 75% recovery. Recovery tends to be a function of the water quality. The membrane manufacturer will limit the recovery to minimize the scaling on the effluent side of the membrane. Systems with high recovery tend to be more susceptible to scaling problems.

With the limited information that you provided, for long term operation, you would probably want a filter and a water softener on the inlet side of the membrane. The water softener is inexpensive and will help to minimize scaling.

I would suggest that you provide the supplier with a water analysis. Provide the supplier with the desired water quality. Specify the desired equipment warranty. Ask for a process guarantee.

You probably don't have the time or resources to get down in the weeds and understand the details of RO systems. Rely on reputable suppliers.

 

[Asisraja D]

bimar
Thank you sir for your valuable information.
Yes we didn't check water quality analysis.

 

[ashtree]

On a single membrane recovery is normally limited to about 15% to avoid concentration polarization. However if you recirculate a portion of the concentrate from that one membrane back to the feed of the membrane it is possible to achieve concentrations up to the solubility limit of the most critical sparingly soluble salt. Ultimately a recirculation rate 3 or 4 times the permeate flow rate may be required. Without having a detailed water analysis its hard to know but it would be likely that 50% + recovery would be possible.

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[Asisraja D]

ashtree Sir
Thank you so much for your information. If you know any blogs or books to understand this concept please suggest me. it will be really helpful for me.

 

[ashtree]

DuPont RO Technical Manual is a good start. However it is technical and requires close reading to develop a full understanding of the subject.

https://www.dupont.com/content/dam/...ents/en/RO-NF-FilmTec-Manual-45-D01504-en.pdf

Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[Asisraja D]

ashtree sir
Thanks for sharing this valuable document.