Design for a DIY marine composting head.

I want to design and build and install a marine composting head in my pair of 25 foot motorsailors.

Stand alone, or, complementing an existing installed head.

Since I have a pump toilet going to a holding tank, I'm thinking a compost toilet that is adjacent or flips down over the current bowl. I like the flip down, pullman sink toilet bowl idea.
Out of the way in unused space of hull flare behind existing head. Easy to seal. Simple to flush(tip up).
And the existing head is for liquid, separation a requirement of compost toilets.
Looking for ideas, input, criticisms, help, all comments welcome.
thanks in advance.


http://www.uscg.mil/hq/cg5/cg5213/msd.asp

"Type III is a device that prevents the overboard discharge of treated or untreated sewage or any waste derived from sewage. This type of device is typically a holding tank and may include other types of technology including incineration, recirculation, and composting. "

"Type III devices.
Ambient air pressure & temperature. A Type III device that stores sewage and flushwater at ambient air pressure and temperature is not subject to formal U.S. Coast Guard certification if it meets the requirements in 33 CFR 159.53(c). Such devices will have no U.S. Coast Guard Certificate of Approval, no U.S. Coast Guard letter, and no device label."

 

The Do It Yourself compost toilet plans on the web, don't seem suitable for a marine head. Most require a separate, remote, and LARGE compost heap.

Three types I've uncovered are, based on 5 gallon bucket, based on 55 gal drum, and LARGE custom built bins. Examples below.

Not what I have in mind.

I want something pretty enough, the ladies will accept it.
Easy to keep clean, compact space, and no flies or smell.
That means sealing well.
Zero or minimum power use.
And sturdy enough to withstand capsize.
And enough cheaper (or better) than commercial units, to make the labor worth while!


http://www.ehow.com/way_5347812_diy-composting-toilet.html

Bucket type.

http://www.youtube.com/watch?v=O0R41RAry_g

Cut down barrel

http://www.how-to-diy.org/ovuPiFiXo9sMNw/Composting-toilet.html

Big Bin

 

Features of design need to include:
A "flushing" mechanism.
A composting bin/storage.
Seals
Ventilation
Cleaning
Stirring?
Removal of composted material.

As to the first aspect, I like the idea Par had of a trap door, except this isn't going over the side.

The pictures below are of a Pullman sink, and a pasted up rough concept of a Pullman type toilet seat that flips down over the regular head.
To reduce height, the stainless Pullman bowl can 'nest' in the porcelain bowl.

 

I didn't know they existed. There's this, I didn't look at it much, it makes me ill just thinking about it.

http://boatbits.blogspot.com/2010/11/most-excellent-composting-head.html

 

I've seen several wooden box with plastic bucket inside composting toilet designs on the web.

Although they claim no odor problems, I recall an old book on small yacht design I read maybe 50 years back.
The author cautioned, the compartment between the veeberths that housed the bucket should be WELL LINED with metal, or soon you would have a chronic smell.

And two objections to a converted bucket system.
Aesthetically pleasing. Not.

And convincing the Cost Guard or EPA, it was a COMPOSTING head, and not a traditional 'Bucket and Chuckit' head, might take some silver tongued talking!
But please post more. All ideas welcome even if not used.

 

Again, on my way to bed; just stopped off here for a quick look. I'll be back tomorrow.

But my first question would be, 'is it worth the trouble to design and build your own composting toilet, when you can buy a C-Head that does the job for about $500.00?'

Obviously, the answer to that depends on your particular mix of energy and ambition vs. your ready cash. Would you be better off spending your time on something else instead, or be better off spending time aon the toilet and saving the cash for something else?

I hope that made sense; I'm three sheets to the wind and falling asleep. Goodnight, all....

 

there was an article on this topic in the a recent issue of "Small Craft Advisor" magazine. you might go look for it. It is specifically oriented towards smaller boats, under 30 ft.

There are some new systems that only use a specially designed self sealing bag. The bag itself is bio-degradable, and chemically treated to minimize odor. The ideas is you seal it up after each use, and than dispose of the bags after returning to shore. My first thought was I wonder how long the bags will hold up, if out at sea several days I would hate to think want might happen if the used bags start breaking down in your boat before you can get them to a compost pile.

 

The simplest and least expensive marine sanitation is the holding tank. Both liquids and solids are managed.
Most human waste is liquid. So a composting toilet, for the solids, really eliminates only a small part of the problem.
But, I like thinking, and this is a good brain teaser. AND, maybe something good will come out of it.

 

Yobi,

Google: airhead compost toilet

Cheers!

 

Found this design

http://www.seapearlboats.org/html/composting_head.html

 

$1090AUD and capacity 60 uses.
My concern is the urine bottle is small, about a gallon.
I drink lots of liquids and pee frequently.
So does my wife.
Is the intent to dispose of urine overboard? It doesn't say in any of the several airhead articles I read.

 

Pat and Mike were drifting in an open boat with no land in sight when they saw a bottle floating nearby. They retrieved it and pulled the cork. Of course the genie came out and offered them just one wish. Mike said," I wish this whole ocean was Guiness" and just that quickly it was and the genie vanished. Pat said, " Mike! Now look what you've done! Now we gotta pee in the boat."

 

I edited out some of the article as not relevant to marine heads, ie: dry toilets for deserts.
Whenever I post excerpts, the intention is to capture your interest enough to read the entire article. hence the url. My defense for any accusations of cherry picking, is here is the url.

http://greywateraction.org/content/about-composting-toilets

About composting toilets

Potential pathogens are killed by a variety of processes, including die-off and predation by other microorganisms. To have a well functioning composting toilet the following should be kept in mind.

isolation: The material should be left to compost in isolation, without potential contact from people, until it is fully composted and safe to handle.
ventilation: The toilet needs a flow of fresh air, to add oxygen and remove odors. All vents should exit the living space.
moisture: A composting toilet should not be too wet, urine diversion helps with excess moisture problems. If the toilet does not divert the urine, or if a small amount of water is added, the material will need more dry material added or extra heating and mechanical mixing.
temperature and time: The rate of decomposition is a combination of temperature and time: the hotter the compost pile, the more quickly the process happens, or if the pile is not hot, the longer it takes. If a humanure compost pile is not monitored for high temperatures it should be isolated for a long time to ensure full decomposition. In a mild climate this takes a year, while in areas with cold winters it may be 2 years.
bulking agent: In a composting toilet sawdust covers the material creating air gaps for aerobic bacteria to break down the material.

Historical Roots
Collecting urine, that magical yellow liquid we excrete from our bodies several times a day, is a key step in recycling human nutrients. Urine contains most of the nitrogen, phosphorus and potassium we release. These nutrients are the major components of chemical fertilizers, and urine is an amazing plant fertilizer! It is typically sterile, and, if separated from feces, can be easily and safely reused. Urine collection can be as simple as peeing in a jar or installing a urinal or urine-diverting dry or composting toilet.



The urine your own household produces is safe to use without treatment. To collect urine in your house all you need is a two-to-five gallon jug or bucket. It must be fitted with a tight cover to prevent oxygen from turning the urine's nitrogen into ammonia, which smells bad and causes some nitrogen loss.

 

As has already been mentioned, the three main commercial composting heads that are used on boats are:

Nature's Head http://www.natureshead.net/ ~$1000
Air Head http://www.airheadtoilet.com/ ~$1000
C-Head http://c-head.com/ ~$500

If you want to make your own you can buy just the diverter seat from Ecovita for ~$100 http://www.ecovita.net/products.html

There have been numerous discussions on CruisersForum.com

A recent thread about someone making his own composting head and using the Ecovita seat is here: Self Designed Large Capacity Compost Head

The longest thread may be this one: http://www.cruisersforum.com/forums/f115/composting-toilets-33029.html

There was a thread on the Junkrig Association Forum here: The 'Haybox' & other composting toilets

The Humanure Handbook may be the most extensive discussion on composing human excrement. The handbook is downloadable for free.

Brent Swain has instructions for making a composting toilet in his book "Origami Metal Boatbuilding"

http://www.nauticalmind.com/Origami-Metal-Boatbuilding-A-Heretics-Guide-pr-66137.html

I think you can purchase the book cheaper directly from him. Contact Swain on this forum:
http://groups.yahoo.com/neo/groups/origamiboats/conversations/messages

 

These composting things with 1 or 2 gallon jugs or bags of whizz you have to store in the cupboard until you get somewhere are only passed in disgustingness by regular marine heads.

How about this idea. All collectibles go in a bag. When 'flushed', the bag automatically inflates with helium, is released and floats away out of sight. If the authorities belabor the point, demand to see the regulations covering the dumping of sewage into the atmosphere and threaten prosecution for false arrest while inferring that you know important people in high places. It's almost guaranteed they will drop any charges and will probably apologize.

It's just that simple and leaves your boat smelling fresh and clean except for the usual mystery odors of inaccessible areas.