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Glass Etchants



All,
I'm looking for any information or leads on the topic of etching glass
(information in the archives was obtained).  Specific issues being
investigated include:
1)	Hydrofluoric acid management
2)	Alternatives to HF including non-corrosive etching methods
3)	Wastewater treatment (fluoride and ammonia/nitrates seem to be the
main issues)
4)	Waste reduction technologies (HF regeneration (is it possible?),
closed-loop rinse systems, sludge management, formal wastewater treatment
systems that might allow effluent re-use))

Thanks, Ric
Illig.richard@dep.state.pa.us <mailto:Illig.richard@dep.state.pa.us>
PADEP
Fax: 570-327-3565						Office of
Pollution Prevention
Call: 570-327-3568						208 W. Third
Street, Suite 101
	
Williamsport, PA  17701
								ATTN: Ric
Illig

If you would like more information about the specific case...
A company is frosting wine bottles (flint glass).  Rather than use
hydrofluoric acid (directly) they decided to use a product called LERITE.
LERITE contains ammonium bifluoride and barium sulfate (we're not sure what
role the barium plays in the process) and is mixed with concentrated
muriatic acid.  Waste rinse water is discharged to the local treatment plant
after pH adjustment.  The frosting bath is used for an extended period of
time.
It appears the LERITE+muriatic acid generates HF for etching AND creates
numerous problems in the process.  The redeeming quality of LERITE appears
to be ease of handling relative to storage and management of HF.  Finished
product quality is excellent so there is resistance to change BUT the POTW
accepting the waste requires the ammonia/nitrate levels to be GREATLY
reduced.
Problems observed include:
1)	Ammonia/nitrate, fluoride, and barium levels are very high in the
discharge (correction required)
2)	Total suspended solids (TSS) are also high
3)	 Barium is expected in tank sludges (for the frost bath, rinse
tanks, and wastewater treatment tanks)
4)	Removal of rinse water dragout from the etch solution generates a
corrosive hazardous wastewater.  The wastewater requires either on-site
treatment prior to discharge or off-site shipment and disposal.

We're weighing the direct use of HF against the issues of using LERITE.
Using HF could eliminate the muriatic acid but may present greater handling
problems.  HF is also a HAP.  Alternative technologies appear to be too slow
or non-existent.  Elimination of the barium seems to be a major improvement
if HF is used directly.  HF would also seem to allow for reducing
ammonia/nitrate and fluoride levels in the discharge possibly without the
need for a formal wastewater treatment system.

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