Water purification systems

Melissa Potter <melissa_potter [at] ago__net> writes

>We are looking into a new water filtration system for washing paper.
>I am interested to know about others' experiences with recently (or
>not so recently) purchased systems.
>...
>A reverse osmosis system with 5 micron pre sediment and carbon
>filters plus a storage tank of 120 gallons has been recommended.  I
>am concerned about the possibility for bacterial growth in the
>storage tank, even with flushing the system once a week.
>
>Is anyone willing to comment of their experiences with RO systems?
>Was bacterial growth in the storage tank problematic?

We have used reverse osmosis water filtration (a Millipore Milli-RO
5 Plus) for some years (water in our area is very hard and heavily
chlorinated), currently buffering with calcium hydroxide. Whilst
satisfied with the quality of water produced, the system requires
regular maintenance (change of pre-treatment cartridges and periodic
replacement of the RO membrane, in addition to regular flushing and
cleaning of the RO unit and reservoir), which is costly when
considering the very small amount of water we use: possibly less
than 5-10 litres a week. This is partly due to a trend away from
extensive washing treatments that were much more common at the time
the system was installed. If we used larger quantities of water, RO
would be more cost effective and probably comparable to other
systems.

I also share your concerns over bacterial or fungal growth, which
can be a problem if water is allowed to stand for any extended
period (fungal growth can be seen in the storage tank after only two
weeks); we try to ensure that the reservoir is regularly emptied and
refilled to prevent this.

The question of water quality and merits of different filtration
systems have been discussed on the Cons DistList in the past, and
whilst much depends on the quality of water supply and intended use,
there still seems to be little consensus about the level of purity
suitable for paper treatments. As the unit we use has now been
discontinued (availability of spare parts will not be guaranteed in
future), we have begun a review of our own water requirements, but
will not need to make a decision until a new system is installed in
new facilities in a few years time. I would therefore also be
interested to hear of other people's experiences.

Robert Minte
Conservator
Conservation and Collection Care
Bodleian Library
University of Oxford
+44 1865 277080


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                  Conservation DistList Instance 22:48
                Distributed: Thursday, February 26, 2009
                       Message Id: cdl-22-48-005
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