Grant Ziebell wrote:
Interested if anyone has comments on the AirHead composting toilet
discussed in Practical Sailor.
Peggy Hall - really interested in your thoughts.
Composters may be a good solution on a "no discharge" inland lake, but
in coastal waters where the discharge of treated waste is legal (which
is everywhere except SoCal on the west coast, RI, about half of MA and
Key West on the east coast), it makes more sense IMO to install a Type I
MSD (i.e. Lectra/San for about the same price and same power requirements.
The real problem with composters is what to do with excess liquids...two
people will produce about about 2 gallons every 3 days. Some of it is
evaporated, but very little...liquids cannot legally be drained
overboard inside 3 miles, so they must be held aboard in something--the
jugs provided with the Airhead or a holding tank...and if you have to
have a holding tank to store the liquids--which, btw, present just as
much of an odor control problem as fecal matter--what's the point of
having a system that separates urine from solid matter? Especially when
you consider that solids don't take up that much room in a holding tank.
A gallon of urine every 30 hours = 5.6 gallons of urine a week. Doesn't
sound like much because it's undiluted by flush water...but the
odor-causing properties in it are also undiluted, especially since it's
not just urine...solid waste is mostly liquid too. Nor is the urine
collected separately...it's drained from the chamber that collects
solids too...so it's "polluted" by e-coli.
And there's something else to consider: temperature. The warmer the
temperature, the more active bacteria (the li'l buggers that create
odor) are...so someone who lives Maine is less like to have any odor
than someone in FL. Otoh, because a certain level of bacterial activity
is necessary for composting to happen at all, composters don't work very
well when the temperature is below 50 F. Since the Airhead doesn't
actually compost, but only removes all the moisture from solid waste,
this may or may not be an issue for winter liveaboards in cold climate
zones, but it definitely is for true composters unless the unit is
heated continuously.
And, there is the matter of power...it won't work without any, so it
must run when you aren't aboard to work...and power can be hard to come
by if you keep your boat on a mooring.
So for someone on a no-discharge inland lake, I'd say it's definitely an
option worth considering...but on a sailboat in coastal waters, I can't
see any advantage whatever--but many disadvantages--to storing waste
aboard instead of treating it and discharging it overboard.
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://www.seaworthy.com/html/get_ri...oat_odors.html