T&T: Re Incinerating and composting toilets

[Peggie Hall]

Both composting and incinerating toilets can be a good solution in some 
applications on land, but neither is very satisfactory for use aboard.

Composting is a terrific concept, but IMHO, it's not quite there for 
onboard use yet. First there's the matter of size. Although there have 
been some attempts at maller self-contained units, the only one that 
works as advertised is the Sun-Mar unit...their smallest self-contained 
"marine" composter needs a space 29" high x 20" deep x 25" wide 
(includes enough room for the handle on the side that rotates the drum 
and enough space to pull out the drawer), making it too big to fit in 
99% of heads. The specs are the Sun-Mar website at: 
http://www.sun-mar.com

The AirHead http://www.airheadtoilet.com (which is not a true composter 
but a dessicator) is small enough to fit in most heads, but has the same 
drawback as a composter, which are:

1. What to do with excess liquids. 90% of human waste IS liquid...mostly 
urine, but even solids are mostly liquid. Excess liquids have to be 
drained off , or you have wet soggy organic material...and wet soggy 
material doesn't compost.   Adding dry material--peat moss is the 
recommended material 'cuz it breaks down quickly--to each flush helps 
some, but not enough, and there's usually more liquids than the 
evaporator--which, btw, requires power--in the self-contained units can 
handle either. The AirHead separates urine from solid waste--the urine 
is directed into in gallon jugs (or a tank.  You can't legally drain 
liquids overboard (unless you're at sea beyond the 3 mile limit),  so 
the jugs must be stored and carried off the boat for disposal ashore... 
tank must be pumped out same as any other tank.

2. Enough peat moss to keep the thing working during an extended cruise 
can take up more storage space than a holding tank.

3. Composters need a 3" vent stack... AirHead originally specified a 3 
vent but is now claiming that a 1.5 vent is adequate.

4. Continuous power 24/7  to run the evaporator.

5. Composting only works in temperatures above 70 F. Below 70, bacterial 
activity becomes so sluggish that nothing happens.

As for incinerating toilets They only run on 115v/ac power, and 
contrary to popular belief, everything doesn't turn to ash in a "whoosh" 
of heat with each flush. The burn time is 90 minutes at something like 
1100 degrees F...which is a lot of power and a lot of heat...and even 90 
minutes isn't enough time to completely reduce everything to ash. Plus, 
incinerators also need a 3" vent/smoke stack, and unless the catalytic 
converter is cleaned regularly, the smoke STINKS!  You can read the 
maintenance instructions for the Incinolet here: http://www.incinolet.com/

IMO, your best bet is a CG certified Type I or II  MSD (treatment 
device) and a small holding tank for use only when you have no other 
choice.

-- 
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and 
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/books/detail-books.htm?fno=0&sku=90&cat=1304