Newsgroups: rec.crafts.metalworking
Subject: Re: Need Sand blasting Help
From: kimberln@crl.com (J. Kimberlin)
Date: 9 Sep 1995 17:28:08 -0700

In article <42t8fd$mi@news1.svc>, Mike Rehmus  <mrehmus@grayfax.com> wrote:
>Might just find that dumping lye down the sewer is illegal.  If you 
>do much of it, best check it out or they may come visit you with
>very expensive charges.
>
>Best,
>
>Mike Rehmus


Mike, I might disagree a little.  A lot of the drain cleaners are simply 
lye and toilet cleaners are lye too.  Thousands of people do this every 
weekend when cleaning their tubes.  Municipal sewage treatment plants 
monitor their pH quite closely.  Basic, up to about pH 8 or 9 won't kill 
the bacteria they depend upon for gas production and aerobic digestion.  

On the other hand don't even think about dumping your sulfuric acid 
copper pickle bath down the sewer.  If you are near the sewage treatment 
plant as I am, you could easily cause an upset.  The rule in 
environmental testing is to adjust the pH of samples to less than 2 to 
inhibit bacterial growth.  Basic doesn't really seem to hurt and is quite 
diluted from general flushing, dishwashing, etc., so that a real slug of 
concentrated sodium hydroxide, or other caustic substance ends up rather 
harmless.

I have to admit however, that removal of paint, grease and other cleaning 
operations using caustic, produce an effluent that should not go down the 
drain.  The effluent is sometime high in lead, chrome, copper, zinc, tin, 
and other metals that kill the beasties we all expect to see when we 
vacation at the seashore or on the river banks.

JerryK