Keith,
          We used to use DTC in three of our facilities, and understand the
     CS2 issue, as well as the other issues you describe. We affectionately
     refer to DTC as Damn Toxic Chemical. We even had one POTW propose in a
     permit revision that we must have at least 1 ppm copper in our
     discharge so that we wouldn't overfeed DTC!
          For almost four years now, we have converted four of our
     facilities to Romar chemistry, which is based on ferrous dithionite. It
     is essentially an iron substitution chemistry for chelated metals, much
     like ferrous sulfate, but without all the sludge, since copper is
     precipitated in an acidic solution. In fact, our experience is that we
     cut the sludge generation in HALF from both DTC and ferrous. So,
     switching from DTC to Romar is not only P2, but waste minimization.
          One of the benefits of Romar is its powerful nature in treating
     chelated metals. We have not had any problems removing lead from
     chelated solutions. In fact, several facilties report non-detectable
     lead levels (using AA analysis). One has even treated two spent baths
     of 1000 gals each and achieved non-detectable levels.
          We'd be glad to show you our treatment system since we're only a
     half hour away.                                        Lee Wilmot
                                                            HADCO Corp
                                                          603/896-2424
                                                         [log in to unmask]
Dear Fine People:
The precipitant we use in our industrial wastewater treatment plant to remove
chelated metals from our rinse waters is dithiocarbamate, or DTC.  DTC has
the unfortunate ability to form the undesirable (read:  strictly regulated)
byproduct/decomposition product CS2 (carbon disulfide), especially under
acidic conditions.  Can anyone offer help in any of the following areas
regarding this dilemma?

1.  DTC management to minimize/eliminate CS2 formation?  Preventing DTC
bearing waters from experiencing acidic conditions seems to be one of the
more obvious interventions.

2.  DTC variants which cannot form CS2 (if they exist)?

3.  Alternatives to DTC?  We have tried several, none seems to match DTC's
ability to precipitate a highly chelated, high lead bearing wastewater stream
to under 0.2 ppm lead consistently.

4.  Easy test kit/method for CS2?

Thanks for your help
Keith Perrin, 
Compliance Specialist
Printed Circuit Corp.