Hi,  

Welcome to the world of recycled water.  You have THE problem, this is THE cure.

1.  Shut down the system.

2.  Peroxide treat all of the recirculation water and the tank, use about 3%
peroxide.  This will kill the bugs.  Keep the DI system out of the loop.

3.Check with your di systems resin manufacturer for the sterilization
procedure for the resin.  Do it.

4.  Add a UV sterlizer on the exit from the DI system and another (that's
2)on the exit from the DI water storage tank.

5.  Use black tanks to store water.  Peroxide treat once per month.

6.  Dump all the water in the system monthly and recharge with fresh.

7.  Your makeup water should go through the di before it hits the system.  I
couldn't tell where you were adding the make up water.   

Other stuff:

8.  You can put individual uv lamps on the problem rinses.  They will put a
little ozone in the water to keep the bugs in check

9. You can use a small RO for makeup water after the softener.  This will
keep the DI just working on your plating chemistry and increase the time
between regenerations (by a lot)

10.  You can regenerate more often.  Most people on a recirculation system
let the TDS rise pretty high before they regenerate.  If you've got a DI
system, make DI water.  Regerate when the tds out gets to 3-5 ppm.  Starve
them bugs!

11.  Increase the flows in your rinse tanks to keep the tds low.

12.  A bob special.  I have here a lamp that is from 9/4/79.  It is a GE
germicidal lamp, that goes in a florescent fixture and has a GE part number
G25T8.  I originally bought this when I worked a Gyrex years ago and it came
from WW Graingers but they do not carry them anymore.  If GE still makes
them, it is possibly a cheap way to continuously sterilize a tank.  I'm not
selling this one (I've been hauling it around for 17 years and it's MINE),
but you could buy them from you're local GE lighting distributor with a
fixture and hang it where ever you want.  But, they generate ozone and are
harmfull to the eyes so they have to be somewhat enclosed.  (if you buy some
of these, let me know, tks)

That's about it, good luck, your're on the leading edge, have fun!

Bob Mesick

You Wrote:
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> 

       I would appreciate any information on plating rinse tanks.  We are
using recycled water in our plating shop and I have noticed that there is an
accumulation of 'slime' on some rinse tanks (particularly after sufamate
nickel).
        Our rinse water is cycled through a DI system and recirculated into
the plating area.  We add enough new water to the system to replenish the
water in approximately two days.  The water is particle filtered, carbon
filtered and softened prior to adding it to the rinse system, so it is in
effect DI water and does not have the chemicals that the city adds to
prevent bacterial growth.
        My questions are:
        1.  Will slime in a rinse tank contribute to poor adhesion of Au
plating on the nickel that was rinsed in this tank?
        2.  How can this slime be reduced or eliminated?
        3.  How often should a plating area clean and/or replenish its rinse
tanks.
        4.  What is everybody else doing to reduce/eliminate bacterial
growth in the rinse water?  The environmental engineer has been
investigating an ultraviolet system but would like additional information on
how other pwa manufacturers effectively handle bacterial growth in rinse
water systems.

                                                Bob Dewlin
                                                Modular Components

        
Modular Components National, Inc.
2302 Industry Court
Forest Hill, MD 2150
PH (410) 879-6553
Fax (410) 838-7629
Remco Engineering (remco.com/home.htm)
Industrial Water and Wastewater Treatment Systems
San Luis Obispo, California  USA

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