Generally speaking you get very high emissions of NH3 when you turn a large windrow. As the other have said, you can limit total emissions by carefully considering the C:N ratio (but even that is fairly imprecise - the type of carbon represented by the kind of C-rich material you are using is also important) and the moisture levels of the co-composting windrow.

I would think that you want a pre-treatment de-watering stage to remove the majority of the liquid otherwise the material will be very difficult to handle.

I agree with Wolfgang that you need to be careful using the residue from chemical toilets as this may interfere with the beneficial microbes that you are wanting to compost the material.

Dear friend,
One of your concerns is the avoidance of NH3 volatilisation. Usually high C content materials are efficient means to avoid loss of N. Another strategy is the lowering of pH (use of citrus fruits waste for example). Start on a small scale, and your noise will be your cheapest olfactory measuring tool to indicate how efficient you are in sequestrating or inhibiting NH3 formation.
Once you have been successful, the compost obtained will be rich in efficient micro-organisms. Keep a good quantity of it to serve for inoculation.

Guillaume

Dear Geoffrey,
Another supplement to your post: According to your description, the mobile toilets are chemical toilets. Sanitary fluids for chemical toilets must be biodegradable. This refers to the discharge in a sewage treatment plant connected to at least 10,000 residents (Germany). If the degree of delution is lower, a single chemical toilet can already influence or spoil the biology of a sewage treatment plant. The contents of chemical toilets should in no case be put into a compost, even at 100 m³ volume.

I recommend to check the sanitary fluid that is used, before going on.
Greetings
Wolfgang

Dear,
the mobile toilet is only a biodegradable product, water, feces and urine (quite easily available here in Belgium). We would co-compost it in a heap of about 100m³ to get high temperature during composting (to get a product sanitised and of good quality). We don't have yet the analysis of the mobile toilet product, and are wainting for it.
This test would be the basis to get idea of co-composting low flush toilet (not widely used here).
What we would want to know is how much we can put in once to avoid liquids to go out of the heap (undesirable), how to avoid high volatilisation of NH3 (odor and loss), and good process to be sure to sanitise.

Does someone have practiced such trial? Or has references?

thanks in advance,

Geoffroy

Dear Geoffroy,

To understand your concern, please inform me about the kind of matter from the mobile toilets. Mostly, mobile toilets are used as facilities on board (e.g. caravans or buses) as well as units for events or building sites. All of them use some deodorant to break biological degradation. This would be of great influence for the success of the composting process.

Best regards

Wolfgang

I am working on a similar project, my target is to heat the fecal matter to 70C for 1 hour, then it can be used as the basis for composting or gas-biodigester without fear of contamination. Unfortunately, this is energy intensive. It may be made less energy intensive if a biodigester with organic material input is used to produce gas for heating.

forum.susana.org/forum/categories?func=v...6897&limit=1000#6960

Hello everyone,
We are a non-profit organisation aiming to integrate better re-use of by-products of off-grid sanitation in Belgium.
In order to base our actions in existing infrastructure, we would perform tests of co-composting of sewage materials (septic tanks, mobile toilets) in a composting facility.

We would mix by-products of mobile toilets (globally in a liquid form) with organics in a windrow of about 100m³. The idea would be to let allow the pile to warm and then to incorporate the mobile-toilets by-products repeatedly by a swather.

Does anyone have reference or experience of such trial? We are looking for a protocole to avoid high volatilisation of NH3.

We would obviously need the final compost to be free of pathogen, either it would need to be incinerated or put in a dump wich would be a pitty....

Thanks in advance for your suggestions,

With my best regards,

Geoffroy