[USCC] Composting waste soap flakes

[Craig Coker]

Reed:

Soap is basically a mix of fatty acids and glycerin (both C-H-O compounds)
that has been hydrolyzed with a strong alkali (sodium hydroxide in the case
of bar soaps and potassium hydroxide in the case of soft, or liquid soaps).
There are often other synthetics added.  Basically, soap is an alkali salt.

I would expect it to be compostable, as the fatty acids and glycerin are
both high-energy sources of carbon to micro-organisms.  To keep the fatty
acids aerobic and to decompose them quickly, be sure to keep the piles
aerobic and keep temps above 140-145 for the first two weeks (if windrows).
The synthetic additives may or may not be an issue.  In any case, I'd limit
the proportion of soap wastes in your recipe to less than 10-15% (and make
sure it's ground up to small particle sizes) until you're sure it's
composting well, then maybe raise the percentage.  Keep an eye on the pH of
the mix and on soluble salt levels in the finished product.

I'd ask the generator for a complete chemical characterization of the
material, just to cover your you-know-what.  That would include: Total
Metals, a RCRA TCLP analysis, and a MSDS.  Then, I'd set up a demo pilot
test just to see how the waste handled in the compost pile (I have visions
of soap bubbles floating across your compost pad...LOL).

Hope this helps.

Regards,
Craig

Craig Coker
Coker Composting & Consulting
3331 Glade Creek Blvd.
Ste. 7
Roanoke, VA  24012
(540) 904-2698
Fax: (540) 904-6732
Cell: (540) 874-5168
craigcoker at cox.net
www.cokercompost.com
 
 
-----Original Message-----
From: compost-bounces at composter.com [mailto:compost-bounces at composter.com]
On Behalf Of Sims, Reed - Colchester, VT
Sent: Wednesday, July 19, 2006 12:15 PM
To: compost at composter.com
Subject: [USCC] Composting waste soap flakes


Hi,
There is a soap manufacturer in our area who wishes to deal with their
soap waste (flakes I think, possibly malformed bars too), and called a
member of our Composting Association for advice on composting the waste
instead of considering it trash.
 
Does anyone have information on composting soap, what recipes would
work, etc. that I can give the company?  We want to support their
decision if possible.
 
Reed Sims
Colchester, Vermont  05446
Tel. 802.951.6796 x243