The Composting container must be kept as dry as possible internally, no urine deposits. It's the fluids, urine in particular that cause it to go 'Off'(!!) .
Best recommendations for 'drying/composting additives i've found are sawdust and popcorn, anything of that nature, even some wood ash.
Venting: Researching some of the literature available there's a lot going for small battery powered fans, actually 12V fans from a PC will work(see Maplins) a with a small gel battery charged from a Small 5-10 Watt Solar panel (see Maplins!) .
I've opted for a 150mmm Drain pipe, right angled to the outside, reaching to above head/hut height with an extraction 'Fan' cowl fitted. Any wind at all and, the cowl turns and sucks the fumes out. A wee bit expensive but nil maintenance..
The internal 'composting box' can be fitted with a lid for removal/replacement with few problems. Best to have two boxes and keep them interchangeable.
Early days of "the Hut" a few of us were still attached to the Military and as such had easy access (with a bit of stealth!) to supplies of Elsan fluid, 5gal drums, as used in chemical toilets. We duly installed a suitable container in a clearing in the rhododendrons to provide some privacy, fitted with a toilet seat.. and an ashtray(!)
As with any 'outside loo' there was always the question of "Who empties it"!! ,. Anyway, on one particular occasion , when there were enough of us around the emptying had to take place. It took about 4 adults to do so, both from the weight of the (full) container and the difficulties in manoeuvering it down the access track to the old mineshaft workings identified as the disposal point.
The inevitable happened, one of the carrying party tripped and the contents (fortunately, only partially !) spilled out over the pathway.
We were left standing, almost consumed within the stench, surrounded by the vile 'preserved' contents from several days spent living in the hut....... It was almost unbearable, overpowering !!!
It happens that one of the lads, when 'obtaining' the Elsan fluid, had inadvertently picked up the wrong container. It wasn't Elsan, it was Formaldehyde... unbeknownst to him... (He had just been the delivery service).
It took some considerable work, with shovels, and water, digging, moving soil, covering with greenery and branches etc. to dispose of and cover the spillage. Even diverting the pathway.
When it comes to 'Outside loos' .. you need to be careful what you put in them... all of the time.... !!!!.
A good design is the 'vent improved pit' (VIP) latrine, which is a composting toilet that can be adapted to varying ground conditions, i.e. water table level, soil permeability. The idea is you have a vent pipe extending down into the pit and up far enough that it clears the top of the superstructure by a metre or so. Paint the pipe black so it heats up in any sun, and the convection pulls air down through the seat and up the pipe, keeping smells inside or discharged above nose height. If there's a breeze it acts like a chimney flu and draws air in through the seat due to the negative pressure caused by air passing over the top of the pipe. Also if you put a fine mesh grille over the top of the pipe flies are drawn into the pit by the odour but are drawn up the pipe by the light - if you keep the inside of the loo quite dim they only want to fly up the pipe. They then can't fly out the grille and get stuck in the pit. If you want to build a community loo then you can build a superstructure over two pits; use one pit until it's getting full, then cover it and use the other pit. By the time the second pit is full the contents of the first will have degraded into some pretty high class fertiliser, and all the pathogens should have died. A relatively small dig can serve a surprising number of people if it's not being used intensively. If anyone's interested I've got some designs of various types from Unicef, Water Aid and others I'd be happy to pass on.
http://www.sswm.info/content/single-ven ... ed-pit-vip
http://www.wikiwater.fr/a8-dry-self-ven ... roved.html
http://wedc.lboro.ac.uk/resources/bookl ... n-line.pdf
http://www.csir.co.za/Built_environment ... _sheet.pdf
http://www.pseau.org/outils/ouvrages/wo ... s_1984.pdf
http://www.h2oforlifeschools.org/index. ... p-latrines,
there's also "vip toilet design drawings" on Google. Might be worth a look for some.
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