The Clivus Multrum composting toilet is one of the most important systems in Canada’s Greenest Home, and company representative Don Mills came up to Peterborough recently to help us with the fine points of the installation.
As mentioned in a previous post, treating human “waste” as a valuable and important resource instead of allowing it to become a sewage problem is an important step in the move toward more sustainable housing.
Now that our composting toilets are ready to be commissioned, it’s a good time to look at how this particular system works, and why we chose this type of toilet system over others.
There are three basic categories of indoor composting toilets. The first – and by far most simple and affordable – is the bucket toilet. We at Endeavour love the bucket toilet, and recommend it highly for its low cost and effectiveness, but it was not a choice for a spec home! A step up from the bucket toilet (in price and acceptability, if not performance) is the self-contained composter. These toilets feature toilet and compost tray together in one unit. These can be effective in situations where usage is light, but do not have the capacity to handle the daily use of a whole household. In order to try to “speed up” the composting process in these systems, heat is often used to evaporate urine and accelerate the decomposition of the solids. But by getting rid of the urine and making the solids dry and warm, a great deal of the valuable nutrients are wasted.
The final type of composter is the remote chamber style. These toilets have a large storage bin able to accept input from multiple toilets. The Clivus Multrum system is designed to make sure that composting takes place in the best possible environment, resulting in the recycling of the maximum amount of nutrient value.
The main tank for the Clivus Multrum system features a sloped base, with fresh deposits entering at the rear end of the tank and pushing older material forward. Once the system is established, there is a large bed of material in the tank. It is a mixture of solids, toilet paper and wood shavings. In this way, the Clivus system is like many others.
Two aspects really set the Clivus Multrum apart. First, the system captures all of the liquid and makes it accessible as a fertilizer. The urine that is collected has percolated through the composting bed, providing benefits to the solid compost as it passes through and changing in chemistry (to nitrites and nitrates) to become an excellent fertilizer with none of the potentially damaging effects of straight urine. This liquid is collected at the front of the tank and pumped into a separate holding tank. From here, it can be applied directly to gardens and lawns.
The vast majority of valuable nutrients that can be retrieved from human waste are found here, according to Don Mills. Simply diverting and/or evaporating urine is to waste a valuable resource.
The second unique feature of the Clivus toilet is the moistening system. The tank includes a sprayer and controls that mist the compost pile regularly with a small amount of water. This provides the ideal conditions for effective composting: not wet, not dry, but consistently moist. Having provided sufficient nutrients, aeration and moisture, the rich colonies of bacteria, protozoa, rotifers, actinomycetes, fungi, mold, yeast and earthworms can best go to work converting solid waste to useful compost. Dry compost material needs to be removed from the tank about once a year.
When fully functional, the toilet will require monthly attention, to mix in wood shavings. The liquid fertilizer can be pumped directly to gardens or transferred to containers to take it elsewhere.
In an upcoming post, we’ll look at the unique foam flush toilets that are the other unique feature of this system.