water quality vs treatment methods

[tr6]

I am looking for a comparison between the various clean water treatment technologies (DI(two-bed, mixed bed), RO, EDI, etc) and the relative expected water quality. I realize that a lot depends on the inlet feed water and equipment configuration, but I am looking for relative comparisions.

 

[EMKWR]

tr6,

I think I can help you. Usually you don't use one technique but a few of them in line. For eample, if you use a RO it might be a good idea to use an UF first to prevent fouling.

For which application do you need pure water? And what is your source?
I can also advise you in the design. I work for an independent company (not connected to any company selling equipment/chemicals) that has a lot of experience in engineering for electricity producers worldwide. As you know, power plants need very pure water.

Don't hesitate to mail me.

Best regards,

Edwin Edwin Muller
KEMA Power Generation & Sustainables
Arnhem, The Netherlands
E-mail e.f.muller@kema.nl
Internet:

http://www.kema-water.nl

 

[GarySCWSVI]

Your question is too general to answer. More dependent upon which to use or which combination to use, is one needs to know the required water quality result. Thats just for starters. After that there are a lot of comparisons to be made as to which to use or which combination to use to fit the requirement. There is absolutely no relativity one can apply that fits a "rule of thumb". That is what keeps Water Treatment Specialists interested in their work. Neither "Monotony" nor "Monotonous" are not in our dictionary.

 

[mohtogh]

Regarding to your mentioned techniques , I guess you search for only those techniques that remove "dissolved solids" .
From this point of view , between DI and RO , RO can produce better water (lower TDS) but this system is more sensitive to suspended solids than DI ,thus for turbid waters DI is better.
From economical point : for TDS >1500 mg/L RO (or DI+RO)
for TDS <100 mg/L DI
For EDI , I must refer to my booklet . If above information is useful tell me for EDI .

 

[tr6]

You are right, my question is pretty general with a lot of conditions and combinations that affect each technology. I have seen comparisions of the different water treatment technologies in various Water-Type of trade magazines; all from a very basic point of view. Unfortunately, I never saved a copy, after-all; as you have pointed out, such a comparison depends on so many outside conditions that it was probably useless. However; a potential client of ours is requesting an &quot;independent&quot; comparision (like from a trade magazine and not from an OEM). So I thought I would see if any of my water treatment colleagues had run across such an animal.

Cheers

 

[GarySCWSVI]

Ultra Pure Water magazine, can't remember the year or month, had an excellent article comparing RO to DI. You can probably recover it by going to their web site at

http://www.ultrapurewater.com

I have all issues since 1994 but can't take the time to find it for you.

To the previous poster, mohtogh: Many DI systems will beat RO for lower TDS on most any water supply with up to 600 ppm. Sometimes even higher. I would recommend, in most cases, that an RO system be installed ahead of a DI unit to relieve the TDS load to the DI resin. Any simple Mixed Bed DI will easily beat any RO on resulting low TDS water quality with a feed TDS up to 600 - 700 ppm. Any good Strong Base Two Bed DI will also beat RO under the same conditions. In a lot of case's even a Weak Base Two Bed DI will also beat RO under the same conditions except the Weak Base DI will not remove Silica. In addition, DI systems do not like Turbidity in the feed water.