Marie:

We do not supply anything in waste treatment, but as a chemistry supplier, we
are intimately involved in the issue.   I advise you that the BEST thing that
you can do to ease the issue, and cut costs is to separate your wastes, and
treat them in different ways.

The presumption is that the only issues that you have in your waste water are
pH and dissolved heavy metals.

Most of the time you can separate your waste streams into the following
categories:

1. Chelated, low, to neglible metal (rinses from resist strippers, alkaline
cleaners, etc.)
2.  Chelated, high metal, (Electroless Copper rinse, and bailout, ammoniacal
etch rinse)
3. Non-Chelated, high metal (microetch rinse, electrolytic plating rinse,
etc.)

On the first category, simple pH adjustment may be all that is required, do
this, and put it down the drain, if the metal is low enough, do not allow the
chelates to mix with category three, or you jack the cost of treatment to the
sky.

Category three can best be treated by pH adjustment, and precipitation of
metal sludge.
Cheap and simple.

Category two is the big expense, and if you mix all your wastes, all the
waste becomes category two waste.   This must be treated by ion exchange, or
precipitation with special chemicals, like sulfides, or weird expensive
organics, to remove the metals from the chelates.

This is pretty general stuff, but it is very often overlooked as a powerful
tool to assist and cut costs in waste treatment.

If I can be of more assistance, contact me off line.

Incidently, if you want to send me your fax number, I have an article on
chelates and waste treatment that you might find interesting.

Best regards,

Rudy Sedlak
RD Chemical Company

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