Composting Toilets ‐ Design 1, The Weekender, Heating the Compost
If the compost can be heated, the microbes will be more active and composting more efficient. Certain types of microbe will die out above certain temperatures, but others will take over. As discussed in previous pages, pathogens will be killed too. Having said that, the need to supply heat to my composting heap is not essential, however, when building my system I chose to install a heater in case it would be needed. In reality, I have never used it. Perhaps in periods of constant use or if I stayed on the property in the middle of winter when outside temperatures drop to about 25 ° F (-4 ° C) and midday temperatures hover around 50 ° F (10 ° C) it would be needed. It is obviously much easier to install a heater when you are making the system in case you need it, rather than add one later! Tropical aquarium heaters with built-in adjustable thermostat are ideal. They're built to be submerged, and a relatively low wattage model will suffice. Depending on the model, temperature can be set using the thermostat from around 68 ° F (20 ° C) to 95 ° F (35 ° C). The only drawback is the need for mains power. This can be overcome if you investigate the use of solar panels to charge batteries and use an inverter to convert 12v DC battery power to AC. I'll create a page about solar power at some time in the future and discuss this in detail. The other problem with the use of a fish tank heater in our compost bin, is the fact that you can't just leave it sitting on the plastic tray as obviously this will melt the plastic, drop through to the bottom liner and m ake its merry way melting through the bottom of the composting bin! To overcome this I created a special platform for the heater to diffuse the heat. I used a ceramic tile, the type used in bathroom decorating or floor tiling. I made the platform as "safe" as possible so the heater would not roll or slip off the platform. This can be achieved by using RTV silicone sealer (fish tank sealer) to glue short strips of ceramic tile to the main platform, creating "sides" and "corners" and some strips across the top. A couple of things to consider - make sure the heater won't touch any of the sealer and think about drainage to ensure liquids won't gather or pool. If you need to cut the ceramic tiles you can get a ceramic tile cutter cheaply from your building supply depot. Scribe a line across the surface of the tile so it's a little larger than the heater. Place the tile on a flat surface with a matchstick under the scribed line at each end. Hold one side of the tile down firmly against the floor. Using a block of wood, apply downward pressure to the end that's raised in the air. The tile should snap along the scribed line.