BOYDA225:  Your problem is either chemical or physical.  Here are my
thoughts on both possibilities, although my experience with similar
wastestreams/treatment schemes suggest that the physical is the greater
possibility.
     Chemical:  You could have strong oxidizers coming into the wastestream
that are wreaking havoc on the organics present, with resultant gassing and
floatation.  I know of one guy who traced his floating problem to nitric acid
wastes that he was metering into the system.  What do you do with your spent
solder strip?  As a short term fix for a problem like this you could
add/meter in a sodium metabisulfite solution.  This seems to work no matter
what the cause of the microbubbles (which I assume you can see on your
sludge).  I notice you got a few responses telling you ways to weight down
your sludge.  You should consider recirculating sludge from the bottom of
your clarifier (if you have any down there-ha ha) if you are not already
doing so.  Use a Wilden M-2 to pump it back to your DTC-addition tank at a
slow continuous rate.  There are many benefits to this.
    Physical:  Any pump involved in your wastetreatment system could be
physically entraining air in the water.  Although it is difficult to track
down the source, almost all of our floating problems were the direct result
of a perforated diaphragm in a Wilden pump or a bad seal on a centrifugal
pump.  If you have a suspect just switch it out with a spare and see if the
problem lessens or goes away.  Additionally any loose fitting or hose on the
suction side of a good pump could be dragging in air.  As mentioned above,
the sodium metabisulfite feed will temporarily fix this problem too.
     I have very rarely seen excess polymer causing a severe floating
problem, although this is often talked about.
     I hope this helps you; if you want to give me a call feel free.





                                                                        Keith
Perrin



                                                                         Lead
Wastetreatment Operator






                                                                      Printed
Circuit Corporation















                                                             617-935-9570x300

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