Recalcifying purified water

Lyndsay Knowles <lyndsay.knowles [at] ngv__vic__gov__au> writes

>We are designing a new water purification system and intend
>including a re-ionization step to raise the pH to at least 8.  I
>would be interested to hear how other paper labs have done this...

When the Newberry Library conservation lab (Chicago) was renovated
in the mid-1980's a deionized water system with re-introduced
calcium was put in place.  Below are excerpts from a presentation I
did at the 1986 Oxford Conference.  If anyone wants a copy of the
complete abstract (3 pages) by snail mail just let me know.

Current conservators at the Newberry can let you know how/if the
system is still working.  My feeling is that this method of
re-calcification is too complicated and hard to maintain, as well as
being expensive.

excerpts from the abstract:

    Chemical solution pail

        Holds saturated solution of calcium hydroxide.  Rather than
        the standard Culligan solution tank, we use a 5 gallon
        "diaper pail" with a handle and a lid.  The uptake end of
        the chemical feeder tube is suspended in the pail with a
        Styrofoam bobber so that calcium hydroxide solution (not
        precipitate) is injected.

    Chemical feeder (Culligan feeder BT-5 has a 19 liters per day
    capacity; feeder DT-60 is 227 liters per day capacity)

        With this pump the calcium hydroxide solution is injected
        into the deionized water line.  The system is set up so that
        the feeder automatically turns off whenever water is not
        being used at the sink.  The smaller feeder is used to
        inject just enough calcium hydroxide to make the very pure
        water non-aggressive to paper.  The larger feeder is used at
        a number of settings-for washing, neutralizing, or buffering
        paper.

    Water flow regulator

        This keeps the deionized water flowing to the treatment sink
        at a constant rate.  This makes it possible to use the
        chemical feeder and get a consistent dilution.

Cathy Atwood
Missouri Local Records Program


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                  Conservation DistList Instance 13:46
                  Distributed: Tuesday, March 7, 2000
                       Message Id: cdl-13-46-004
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