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RE: Metal Filtration



My experience with stainless steels is that they do not contain lead in
their composition.  If this is true with your grade of stainless steel
(there are many) then you may need to look elsewhere for the source of
contamination.  I would suggest that if you have not already had some of the
shavings/grindings analyzed for lead that you do that first.  If your
material does contain lead then you should look at other stainless steel
grades or other metals which do not contain lead.

If there is no lead in the metal you have analyzed then you need to look
elsewhere.  A few thoughts might be things like gasketing materials, clutch
materials, and other materials used on rubbing surfaces to either lubricate
or control rotating/movement.  Many dry film and other lubricants have
contained lead in the past due to its great lubricity.  Fortunately, if this
is the problem, there are now many very good replacements for lead based
lubricants. These things eliminate the source and you can mop or whatever
else without picking up lead contamination.

If you can't identify or eliminate the lead contamination you might look
into re-using the mop water after the filtration you currently do.  If you
can filter it and use it a second time your volume of waste water is half of
what it is now.  Re-use multiple times really drops the volume quickly.  You
should also consider ultra-filtration.  This might actually remove the lead
contamination and other material from the water allowing re-use many times.


If you find the exact source of the contamination you should be successful
in eliminating the lead by substitution or re-use.  Good luck.


> ----------
> From: 	Ronald_A_Del_Mar@rl.gov[SMTP:Ronald_A_Del_Mar@rl.gov]
> Sent: 	Wednesday, July 26, 2000 2:17 PM
> To: 	p2tech@great-lakes.net
> Subject: 	Metal Filtration
> 
> We have a waste stream generated from the mopping of floors at our
> fabrication shops that routinely tests out with concentrations of lead in
> the 10 to 20 ppm range.  Our guess is that the lead comes from metal
> shavings resulting form grinding/cutting of stainless steel.  We currently
> generate about a drum a month of this mop water.  We are looking at a
> number
> of options to reduce this waste stream, including reducing frequency of
> mopping, doing a better job of catching shavings before they get onto
> floor,
> improved housekeeping, etc.  Another thing we are trying it filtering mop
> water to reduce concentration in water to below TCLP limits.  This would
> leave us with only the sludge to manage as hazardous waste.   We've tried
> running the water through a 25 micron filter, but this had essentially no
> impact on the concentration of lead in the mop water.  I assume we need to
> go to something much smaller -- probably more of a multi-staged filtration
> process.  Anybody have any ideas as to what might be sucessful in removing
> the lead from this mop water? 
> 
> Ronald A. Del Mar
> DynCorp Environmental Programs & Compliance
> (509) 376-2186 (fax) 372-1694
> ronald_a_del_mar@rl.gov
>