xavier be

And hey Diltek, i definitely suggest checking out the compost toilet handbook from joe jenkins. In there he talks about toilet systems for a number of emergency situations, including composting for a few thousand people at standing rock USA.

https://slateroofwarehouse.com/Books/Joseph_Jenkins_Books/Compost_Toilet_Handbook

Sorry for the late results everyone, but here it is:



So, it didn't get to the required temps. I think this is because no water was added after the 4 day event, so once it dried out it cooled down.

We had some meetings with the municipality, and we will go with a different method. We will simply use unmodified IBC containers to collect the toilet material, with 30-40% pre filled with sawdust. They will sit for one year, then be emptied into an outdoor compost pile the week before the next event.

Heres an update:

We had a small event last weekend, around 50 people for 4 days. We built a prototype compost inside an IBC tank to see how it would go.

First the top of the IBC was cut off


These air pipes were connected to a plastic pallet, which also holds some textile to keep the straw onto the side of the tank


This construction was placed inside the IBC, and the sides and bottom were filled with straw


Finished construction


I estimate only 50-60% of the capacity remains after the insulation straw and drainage pallet is added


Here is the full tank after the event, we also added food scraps


Both an analogue and digital thermometer are used to record the temperature


We had one indoor toilet and one in the barn


We filled it with around 100L poop/pee/sawdust, 75L food scraps, drained and re-added around 80L leachate. There was definitely still room left.
After the event, the compost thermometer read 21C, outside temp was around 7-13C. The next day it went up to 30C - so its working already! We will get the digital thermometer results in a month or two.

I actually emailed Joe, he responded after we had already built it and said the air pipes are probably not necessary:
"The oxygen issue is way overblown. As long as the organic material is not under water, there will be oxygen in the mass. There is no need to add it. That's why compost can be made on concrete, in brick bins, plastic bins, etc., without needing to add any additional oxygen, pipes, air holes, or anything else. Unless the pile is too big. Then it can smother itself. Just don't make it too big. It's that simple. Too big means too high. A maximum height of a meter and a half seems to work well."

Morfydd St. Clair wrote:I have nothing to add regarding technical details, but suggest that perhaps you could reach out to Natural Event ( products webpage ) for ideas.  I know that before the pandemic they provided composting toilet services to at least two festivals I attended with good results.

Thanks, yeah I have a friend that just went to Waking Life in portugal that uses their toilets. Got some info about their toilet design but not their composting process, most companies want to sell their services or consulting, not really share information. Boom festival also doesn't want to share info about their system unfortunately.

You could try Jeff Lawton's wheelie bin design.  I'm a little nervous about sending the leachate straight out though.  Maybe if you added worms so it could act a little more like a vermifilter.  Joe Jenkins suggests using wheelie bins might work great for municipal emergencies in his Compost Toilet Handbook, but more for the sake of transport.  You might find the book interesting as it covers many applications of his system around the world.

We wouldn't actually send the leachate out, but simply add it back to the bins so it can be absorbed again by the compost, and evaporate, as they do here: https://www.youtube.com/watch?v=8lkBAiakmno&t=1569s
As we'll be composting in IBC tanks, adding worms seems like a good idea as they cannot enter naturally from the ground—I guess after the main thermophilic phase is the time to add them.

Im going to need to read up more about vermifilters, and get onto the compost toilet handbook!

Watching that o2 video, it seems like the air should be pushed into the compost, not drawn out of it as in my previous drawing. I could definitely see that working with an insulated IBC.

Just an observation.

You are concerned about leachate, which in understandable.

My experience has been that this is highly dependent on exactly what type of sawdust you are using. There is a vast difference in ability of different sawdusts to absorb liquid, and hence their tendency to go anaerobic and leach liquids. There are also differences in use that can affect this. For example, using "too much" sawdust is never a problem. At worst the compost is a bit slow to get going. But using too little sawdust can result in wet anaerobic sludge. Err on the side of going overboard with the sawdust and you should avoid leachate altogther.

Our best has been sweet chestnut sawdust from a local fencing yard. They can give us cubic meter bags for free. Their dust is very fine and dusty. A bucket of this after a few days of normal use is odourless, and the moisture from urine is evenly spread through the dust. There are no wet an sloppy portions to splash when you transfer to a heap.

Next has been our own dust from running the chainsaw. Tends to be bigger pieces.  A bit less absorbent, but adequate.

The worst was bought in pine shavings. We urgently needed an extra loo when the indoor toilet was not working for a week. Bought a few bags. It was basically waterproof. A wet sludge was at the bottom of each bucket. It was a pain to use, nasty to clean up, and slower to compost afterwards.

Thanks for this info, very valuable. Unfortunately I have just found out that there is a massive shortage of sawdust in Sweden—yes its crazy. This is because many people use pellet heaters in their homes, and the pellets are made from sawdust, combined with the general wood shortage. We have contacted a few sawmills but they only want to sell to municipalities or big companies.

We can buy wood shavings, but it sounds like thats not the way to go—they are probably pine. I have read online somewhere, about someone putting straw into a big bin, and using a weedwacker to cut it up into dust. We can get straw bales from the farmer on our land so going to give this a try.

The toilet system we had this year used biochar, not really as a cover material but just to absorb smells. Has anyone tried using it as the main cover material?

Burton Sparks wrote:Xavier, I think the IBC tote is an interesting idea.  I've managed composting toilets for a 3-day event with over 75 people.  We opted to use 55 gallon drums using the Omick Barrel Design but without urine diversion to reduce maintenance all around.  We received lots of positive comments and no negatives.  The barrels were hard to move though.  In my experience people prefer the depth of a 55gallon drum over the 5gallon bucket.  IBC totes would allow you to move them with a tractor, provide a comfortable space between user and the growing pile, and control leachate.

In the Jenkins method (which I currently use) the deep cover layer on the bottom and sides, along with digging a depression in the middle for fresh deposits helps keep the pile sufficiently aerobic.  Early on I wasn't doing a good job digging the center depression and noticed actinobacteria building up, indicating it was starting to go anaerobic in the middle, but it never went fully anaerobic.  On the flip side, I've learned to put cardboard around the sides of the piles because I've seen winter winds kill a pile in a matter of hours without it.  Based on my experience I'd worry that an IBC tote would not give you the air you want to stay aerobic, but having said that, high enough temperature over time will still kill pathogens even if it goes anaerobic and stinks.

If the pallet doesn't crack the raised edges of the base ridges and sides of an IBC tote under load, you could consider crossing the your proposed design with a Johnson-Su type passive aeration system (all compost is within a foot of an air tube).  You'd want to cap the air tubes during use/fill, and align them so they don't sit directly under the toilet seat.  You could also surround each IBC tote with something like a Tree Bog, with a front gate to allow removal by tractor.  In the storage location you could insulatie the outsides with strawbales.

For this method to effectively hot compost, you'd want to fill each bin rather fast (1, maybe 2 days) because it'll start to heat quickly.  You may also want to have a way of having the maintenance crew spread the contents within the bin being filled, perhaps using access hatches like ceiling tile boards for the "bathroom" floor.  As an alternative, if you have access to electricity you could consider setting up an active aeration system inside the IBC totes similar to the O2Compost Micro-Bin, which would allow you to fill the bin over the full week.

Super info, thanks.
- Do you need to have a leachate tap on your Omick system, as you're not diverting urine, or is the sawdust sufficient to hold all the moisture?
- It seems the vent pipes in that system do not extend down to the bottom of the barrel, do you need to manually aerate them? or do you empty them into a "Jenkins pile" immediately when they are full?
- If filling within 1-2 days is necessary, then I guess IBC's might be too big - it would take the whole week for us to fill each one. Then perhaps wheelie bins are the way to go, like this https://www.youtube.com/watch?v=rlml3Lmdv2o - basically like the Omick but easier to move.

We do have electricity, I wonder if an IBC system like this could work with powered ventilation - couldn't see the specifics of how the o2 system works:

Hi Xavier:

I'm Jeinny and we manufacture WCEco compost toilets, we rent them for masive events, we have a collection service in 5 major cities in Mexico, and process everything.
The largest event we have handle was an Ecobazar with ~6000 visitors during 2 days, but it's not the onlu one. Before that we serviced a Bycicle race with 2400 participants. And we are just getting ready for an event of 45,000 next month.

We never use diverting systems in public events, as they always lead to problems because people do not know what to do with the sawdust and tend to screw it. We use 20L buckets and have personnel there to change them and to be sure everything is going right. It's important and conveniento to use enough sawdust. Not only helps to have a 30:1 carbon:nitrogen ratio, but also, not diverting adds adequate humidity to the compost process.

After the event we process everything in composters 2x2 m composters. But recently we worked with a major university here in México to test the pathogen charge of the final product after a year in the composter and after processing it as bokashi and found that not all pathogens are gone, so know we are being extra cautious and we are working in making some changes to the compost process. So, I'm pretty sure the volume in a bucket is not enough to reach adequate temperatures to kill pathgens. I would recomend to process externally in composters larger dthan 1 m3.

You can see some images of our cabins for events here:
https://www.facebook.com/media/set/?set=a.1571973673228019

And some images of our composters here
https://www.facebook.com/media/set/?set=a.1571991936559526

Hey Jeinny, awesome you're doing this on such a large scale! Thats exactly the conclusions we had this year after trying separators. Im a bit unclear as to what you meant with the lab results—was it both your compost piles and a separate bokashi method (in buckets?) that were not successful in removing pathogens? Did you monitor the temps in the compost? We will definitely have at least 1m3 compost containers. I guess your climate is quite warm there?

Hi Xavier
I could not find a definitive article on Mitigation of pathogens through anaerobic digestion just many articles suggesting this is the case.    The ideal temperature for digestion occurs about 90-95 F.    Digestion also occurs at temperatures  120-150ish with a different type of microbes and this range i understand is more effective in reducing pathogens.    You need about a 30/1 carbon to Nitrogen ratio for optimum results so sawdust would be beneficial.     Also i did not mention that this process works better as a slurry (probably about 1/1) so more handling is required to add water.     I agree with Michael that your bucket system and even more so your tote system will quickly go anaerobic unless transferred to some other containment.    The batch system i described above is very similar to what I built years ago except I used a tractor tire inner tube to capture the gas.  
I think the promise of fast aerobic decomposition is rarely realized due to not being able to achieve aerobic conditions throughout.    Compost piles must be turned.  
Another issue I see with this festival waste stream even after successful remediation, it will contain trash and cups and more than a few cell phones so where do you put it to not pollute the environment?    You may still be faced with having it processed through a municipality.
I would like to know more about the system used at the festival Michael mentioned.    
This is great problem begging for a great solution.  

90-95F should be possible if as you propose, the methane could be used to heat the building. We have also considered using a heating jacket like this: https://www.drum-heater.eu/product/heating-jacket-200lt-90-h800 which should be able to get the material up to 65C/150F to sterilise everything. If the result is a slurry, I think we will need to get that approved with the municipality first, their guidelines only allow composting so far.

I'm curious about your statement that the piles must be turned—there is a whole chapter in the Humanure Handbook called "compost myths" outlining why this is not true and actually bad for the process, he has been making working piles since the 80s without turning. There's also plenty of videos of people using his system and not turning their piles: https://youtu.be/_4oHdfFufOM?list=PLdpeKk29EPYTrw2ZvWxdPNVroH8XCPIUl&t=252

We're lucky that our event has a big focus on leave no trace, so there is generally not much trash in the toilets, people carry their own cups etc. We will use the final resulting compost ourselves, so I imagine it's easier to pick out any trash at the end of the process when it is less like poop and more like soil. I could see how this would be trickier if we are using anaerobic slurry though.

Thanks Michael,

I've used composting toilet for multi-day camps of up to 50 in the woods. Probably about 250 person-poop-days, total. Based on the Humanure Handbook system of sawdust, buckets, and keeping urine and poop together. People inexperienced with sawdust definitely do make a mess, and are hesitant about using it at first. From a user perspective, it it is important that each user does a "flush" with a scoop of sawdust to leave it clean and welcoming for the next person. Loose sawdust spills on the floor and looks messy.

For something like a festival I would go for a floor with wooden slats so loose sawdust drops through and doesn't build up.

If using buckets you need someone dedicated to swapping them out and keeping the area clean.

When you are done you don't really want things composting anaerobically in sealed buckets. Ideally you want a really hot aerobic compost heap. This is very situation dependent, but you could haul buckets off site and have a heap elsewhere. For the scale you are looking at I would probably construct a long "wall of haybales, so you can empty buckets over the wall without risking any splashback etc...

Getting it out of containers as soon as possible and into a compost heap does seem to make the whole process less stinky and unpleasant. And if being used correctly, with plenty of sawdust, no stage of the process should be stinky anyway. Nasty stink only happens with insufficient sawdust, not using it to cover between each user, or if it get sealed airtight and has time to go anaerobic. Sawdust is amazing at absorbing odour, and getting a really hot and sterile heap up to temperature fast.

This is exactly the system I would have liked to use; a big haybale fort, theres a video on Joe's channel about a big festival using it here: https://youtu.be/a_DQyO2CPV0?t=335 Were not too worried about cleaning up sawdust, it was cleaning poop out of the urine separators that was the problem.

However our municipality requires composting have a sealed bottom so leachate doesn't get into the environment. This complicates things, we could either build a concrete containment system like this: https://www.youtube.com/watch?v=8lkBAiakmno&t=1569s or, a similar setup using IBC's to do the final composting in which will be a bit cheaper:

If we could skip the step of taking the 20L buckets to the final composting, and figure out a way to have the toilets directly on the IBCs that would be great. I guess as Doug says it will be tricky to ensure enough oxygen is getting im. I have been thinking something like this could work, its basically the same structure in the end as one of Joe's piles:


Its insulated on the sides and top, all liquid are drained, and it should be filled within one week. Air will be able to enter through vents cut into the IBC. Im really hopeful about this system and will test one at a 300 person event in October, will definitely report back here with the temperature results.