bucket system in cities - any practical experience?

Hi all, I'm looking for a cheap, clean and efficient way to use a dry toilet in an apartment in a city, without access to a larger compost pile where you would dump it once full.

I was wondering if using a 15-20 liters bucket, just adding sawdust, and then closing it and letting it decompose somewhere below a table, would work. The bucket number used would be about 15-18 per year.

Only small amounts of pee would go in this bucket. Pee would go in another bucket filled with sawdust.

Only one/two people would use it.

Worms could be added to speed the composting process.

After one year or so, the compost would be put in a nearby park to fertilize the trees.

What do you think?

greg

Hi Greg - I like your line of thought. However, coming from a watershed health perspective and having worked with regulators I do not recommend taking your composted humanure off of your own property. Other potential issues you will face with such a system is 1) amassing a substantial number of buckets, 2) maintaining an aerobic composting process in a closed bucket, and 3) over-saturation of the sawdust bucket quickly by the urine and then being gassed out by the resulting ammonia.

If you do not have space for composting in a larger "batch" system I would recommend looking at a commercial-based composting toilet system that can evaporate the urine and speed up the composting process.

Hi Greg,

If you have the space for 15+ 5 gallon buckets (15-20 liter), I think you might be better off with a 55 gallon batch system, like the one Watershed Management Group promotes. If only 1 or 2 people are using it, you can probably manage with just 2 units. The urine diversion will be the real problem with this, since you can't direct this outside, so I agree with Catlow that a commercial system that evaporates the urine will be better for urine management.

In regards to finding a good place to use the compost, are there any urban farms nearby that would want it for their trees? You would definitely want to find a location that wants to accept your humanure.

I'm wondering if you can't divert the pee into a container with some water in it and just take it out once a day to water some nearby trees (if there are some close by).

If you didn't want to save the pee - you could divert it down the tub/shower...?

Greg, I don't know what city you are in, but you might have luck finding someone that is already composting humanure. Most of us wouldn't mind additional deposits being made to our piles. You could check the much smaller, but more focused, Humnaure Forum, or maybe someone here on permies will host you.

Hi Catlow, Lisa, Jennifer and Fred,

thanks for your comments!

@ catlow: will an anaerobic process still occur if the bucket is not airtight? I am interested in exhausting all low-tech options before considering a commercial model.
@ Lisa: I LOVE the system you guys promote! Just a question: how do you lift the batch once full?
@ Jennifer: that's a very nice way to solve the pee issue.
@ Fred: I was considering any city. I personally live on the land, so I have no problems to process humanure, but there is a 8 million people city (Bogota) not so far away, which means a LOT of potential clients for such a system

Hi Greg - I am not familiar with composting humanure in a small 5gal bucket and how to best manage it. I think the bigger issue is to ensure there is a meso to thermaphilic composting process that happens without the significant mass as a 55gal container or a larger humanure composting pile has.

With regards to lifting and moving a larger (55gal) batch system - we have experimented with some success on either sliding or putting the barrel on a coaster wheel base to switch it out of position and insert a new barrel.

- Catlow

Catlow are you familiar with people using garbage wheelie bins as a large container?

Wyatt - Yes, I have seen designs for using a wheeled bin as a direct receptical. Typically the toilet is in an elevated room. A vertical chute under the toilet goes to the wheeled garbage style bin underneath with easy access to switch out the bins as needed.

Here is one link to such a system. There are dozens of variations: http://www.milkwood.net/2011/04/18/compost-toilet-specifics-the-bins/

Thanks for the link Catlow, I had seen the milkwood system on line but I don't think it is suitable for my area without some fairly major changes. Wheelie bins yes but no to the blackwater drain. My main aim is nutrient recovery and in most places in Canada that means holding material during the cold time of the year. Compost is ok since it can go dormant (freeze) without nutrient loss but any kind of draining system means loss for about 6 months of the year. The Jenkins system is fine for me at the moment but I would like to get a handle on a bigger less physical system for the future.

Wyatt - Have you considered a double chamber system? Modifications would need to happen for your cold climate. I have attached some schematics we have developed for Arizona. This is probably the least intensive for management once setup.
- Catlow

Thanks for the document Catlow, I have been researching double chamber systems and expect I will either end up with a double chamber or possibly a double bin system incorporating vermiculture as well. One of the main things I hope to do is remain adaptable and not lock myself in to a system that can't be converted.

I think a double chamber would be workable with a basement or with extra insulation on a southern exposure.

We use a double chamber system and I'm happy with it.

It's two chambers with the cheapest readymade doors, so that's 2'6" wide, the chambers are about 7 or 8 feet high, and I think they're 8 feet long. They're this large because we've got dozens of people living here. We have seven pairs of the unit I describe here, and our population at this school ranges from 40 to 150.

Early spring is when we normally empty the chambers that have been standing a year. We then fill a couple of feet some carbonaceous material in the bottom, open the holes over it for use (we've got two holes over each long skinny chamber to distribute the manure in the chamber), and cover the chamber that has been used for the past year. Since we're actually producing more compost than our gardens can absorb, with all the people and 3 cows, we usually empty the chamber and pile it right outside for another year, or till the compost is needed.

We happen to be on a gently slope so the user walks in from the uphill side, and when you empty it, the manure chamber doors are downhill.

No need to shift buckets out to a pile when they are fresh. By the time you empty a chamber that has been standing for a year, it's all decomposed.

Ours is an outhouse. If you attach it to the house you'd need to prevent the moist manure from soaking through the wall. Though actually there's a bathing block attached to one set of our toilets, and it hasn't soaked through the wall in 15 years. I forget what treatment we gave the wall. It might be stone with a cement plaster, with some waterproofing goo mixed in the plaster.

We didn't insulate the chambers. I'm sure the outer parts freeze solid in winter, but since we never go in there in winter, why does it matter? Just leave it long enough and it will decompose.

With a large chamber it's not as easy to completely cover each deposit as it is in a bucket, so we do get flies. We have a bottle trap on the outside of the manure chamber doors -- the flies go towards the light and get into the bottle, where most of them can't figure out how to go back. It does reduce the number of flies but doesn't eliminate them completely.

Most of the people here don't pee outside in public places, so sometimes in a long cold winter, especially at the girls' toilets, there can be some unattractive icicles at the bottom of the manure chamber doors -- leaving some of last year's manure piled up against the bottom of the door helps with the aesthetics. Also, I added some perforated pipes on the bottom of several of the chambers, because very occaisonally one chamber goes anaerobic and smells when we empty it. I don't know, maybe the pipes have helped aerobic decomposition as well as reducing seepage.

One of the changes I would make to a double chamber is a drain at the bottom into a removable container. This would allow excess liquid to be returned to the chamber at a drier time or be mixed with cover material and put back. I am not a fan of blackwater drains in alternative systems.