It happens to us, so why can’t it happen to bacteria? The grey dreariness that often makes us want to go into hibernation mode (if only work, life, etc. would let us) also slows down the metabolic rate of aerobic bacteria.
The air temperature around the compost in a self-contained composting toilet remains at room temperature since the compost chamber sits inside the pedestal within a bathroom. However, a split-system toilet with a pedestal in the bathroom and compost chamber outside is exposed to the elements and can experience slow composting during colder periods.
The optimal temperature for composting is between late spring, summer and early Autumn where daily temperatures never fall below 13 degrees. Below this temperature, the composting process will slow or even stop completely. That said, while the outer layers of your pile are at the mercy of the daily highs and lows, the centre of the pile can still be warm and actively composting because of heat generated by bacteria. As air temperatures warm up in the spring, microbial activity will resume throughout the pile.
If you want to speed things along during winter simply follow these tips to get those microbes munching along happily in your split system:
Moisture and Oxygen
A compost pile needs the right amount of air and water (in addition to carbon and nitrogen) to be successful. So when temperatures drop the pile may retain its moisture for longer than drier summer months. So while water in the summer may be a necessary amendment, the addition of too much moisture in winter months (i.e. urine) will force air out of pore spaces in your compost pile, suffocating our dear aerobic bacteria friends.
The use of a urine diverting pedestal in colder climates provides control over the moisture content of the pile. To use such a pedestal does not mean you have to sacrifice the look of your bathroom. Manufacturers have now streamlined the design and attractive looking urine diverting pedestals are readily available.
Increasing the amount of carbon in the pile by adding bulking agent such as wood shavings during winter is particularly important. Ensure the bulking agent you are using is between 1 to 3cm in length. The finer bulking agent is great for increasing surface area for the microbes to work on but too fine and you reduce the ability of the pile to be aerated.
Ensure your ventilation fan is running 24 hrs a day as well since this will help dry out the pile via the internal aeration pipes or laminar flow (depending on the model).
As the composting process will slow down during winter time, the chamber will be filled up quicker. If this is the case, you may need to heat or insulate the chamber. Less technical ways of doing this over winter are by (a) creating a box with hay bales and lid with an upcycled window arrangement, (b) wrapping the chamber in insulating material like a yoga mat or bubble wrap or (c) placing the chamber in a pop-up greenhouse.
In particular cold locations, some customers have syphoned air from their roof space and using the existing ventilation system pulled the hot air through the chamber.
Some models are often placed directly under the house and stay static connected to the waste chute. The additional sealing off of the area around the unit with the use of glass, perspex or another transparent material, on the sun-facing side, will drastically increase the temperature of the compost pile.
Ecoflo Wastewater Management has been experimenting and we have now finalised our research and development on the heater pads, for Nature Loo Classic 850 - check out heater pad; and Clivus Multrum (CM8-CM40) models, see 240V 250W heater pad for more info. In the meantime, if you have any of your own tips we'd be happy to hear them!