Our top of the range eco toilets, are composting toilets that use a natural aerobic process called thermophilic composting.
Aerobic microorganisms (AKA microbes), including actinomycetes bacteria and fungi, break down the waste which produces heat and removes pathogens from the material. This process transforms waste into an odourless compost that is safe to handle. The length of time to compost depends on climate, chamber size, and composting conditions.
The four main factors affecting compost
Moisture
Too dry and the dehydrated microbes will hibernate and eventually perish. But too wet and the conditions in the chamber become anaerobic killing the microbes. The perfect balance is 60% of moisture content by weight.
Oxygen
The incorporated ventilation is a simple fan that draws air through the composting chamber and disperses it externally. This encourages airflow for the oxygen-breathing microbes.
Carbon & Nitrogen
Microbes utilise both carbon and nitrogen to maintain a healthy lifestyle and to grow and reproduce, forming a strong culture. An ideal C:N ratio is 25:1 for a composting toilet, hence the use of a carbon-rich bulking agent to balance the naturally nitrogen-rich human waste.
Temperature
The key composting microbes are thermophilic, meaning that they create heat and they prefer warmer conditions. This is why the composting process slows down and eventually halts when the chamber is cooler than 12 degrees Celsius (53.6 degrees Fahrenheit). Thankfully, the cold won’t kill off the microbes but just cause a state of hibernation from which they can be woken up.
The four stages of composting
1. Mesophilic
Mesophilic organisms, which thrive between 20 – 30 degrees Celsius (68 – 86 degrees Fahrenheit), are breaking down easily decomposable materials like toilet paper. The temperature increases as they proliferate.
2. Thermophilic
Thermophilic organisms grow and thrive between 45 – 70 degrees Celcius (104 – 158 degrees Fahrenheit). This is the rapid decomposition of complex organic materials, generating higher temperatures and killing off pathogens.
3. Cooling
When there’s nothing left for the thermophilic organisms, the pile starts to cool and the mesophilic organisms return as the majority. Actinobacteria (and maybe some fungi or mould) will finish decomposing any remaining materials at a slower pace.
4. Curing
Naturally, when the pathogens are killed off and all the material is broken down, the culture of microbes starts to enter a stage of hibernation. The composting pile has matured into a humus, with an appearance and consistency similar to that of fresh potting mix.