Talking About Toilets…Composting Toilets

donate-2Yes, you read that correctly.  Today’s post is all about the composting toilets at ThorpeWood.  Many of you already know that ThorpeWood is a green design building, and that protecting and preserving our natural resources was the driving thought behind the construction of the Lodge.  One of the ways that we help to do that is by utilizing composting toilets, and let’s face it, that has been an area of interest pretty much since the beginning.  What many of you might not know is how these composting toilets work and why we feel they are such a benefit – not only to ThorpeWood – but to the environment as a whole.

Let’s begin with an environmental impact factoid: 12.5% of nitrogen pollution in the Chesapeake Bay is from septic systems.  According to the Chesapeake Bay Foundation, both nitrogen and phosphorus feed algal blooms that block sunlight to underwater grasses and suck up life supporting oxygen when they die and decompose. These resulting “dead zones” of low or no oxygen can stress and even kill fish and shellfish. Algal blooms can also trigger spikes in pH levels, stressing fish, and create conditions that spur the growth of parasites.

Instead of a conventional septic system, ThorpeWood uses a nutrient recycling system that returns nutrients to the earth. Our composting toilets are manufactured by Clivus.  The Multrum system we use converts human waste (solid and liquid) and food scraps into odor-free and safe-to-handle solid compost and liquid fertilizer.

Whereas the typical toilet uses between 1.6 and 8 gallons per flush, the Clivus uses no water for flushing and a negligible amount of water in the collection chamber. Pine mulch and red worms help the composting process. Air flowing into the toilet initiates sanitation of fecal matter and sanitizes fixture surfaces without the use of chemicals, while fans pull air down the toilet chutes and  vents from one of the cupolas. roof windows, keeping restrooms odor-free at all times.

After slowly migrating through a bulking agent of pine shavings several feet thick, the nutrient rich liquid is temporarily stored in a large tank in the basement of the the Lodge, awaiting to be transferred to a mobile tank and  taken to an open field to be sprayed onto the grasses.  This process happens about four times a year and approximately 3000 gallons of this Clivus liquid is land applied. Solids from the Clivus are removed one to two times a year.  The material removed has broken down to such an extent that nothing is identifiable and it resembles coffee grounds. The amount removed is approximately the volume equivalent of three to four 30 gallon trash bags.  The complete decomposition cycle of the solids is four to five years.  Solids go into our horse manure composting piles and eventually go back onto our horse pastures as fertilizer.

All human waste, solids and liquids are handled as described above.  The composing toilets effectively reduce water consumption at ThorpeWood by 75-90%. The plumbing separation of human waste from all other wastewater, called gray-water, allows us to handle the gray-water differently, ie. not as septic or sewage.   In conjunction with the Clivus Multrun composting toilets, we have gray-water nutrient recycling system, which land applies the gray-water (soapy water with no human waste) to a series of shallow (6 inches deep) troughs.   From these troughs the water is slowly percolated into the very active microbial layer of topsoil and is stripped of much of the nutrient value of this water before the water goes back into the ground water.

There is nothing high tech or sophisticated about this system.  The basic principles are to replicate as near as possible the natural process of nutrient uptake and water purification …amazingly simple really.

Yes, you have just finished reading a blog post about toilets!  The next time you come up to ThorpeWood, make sure to check them out.




Posted in Nature Preserve
3 comments on “Talking About Toilets…Composting Toilets
  1. I’m wondering if you had any code issues? I would love to build a house on land without an existing septic system, and use a black and gray water system similar to yours. Did you have any problems getting the county to approve your waste treatment plan without a septic system? Thanks!

    • joann says:

      Trouble? Well …….perhaps you can call it trouble. Our approval was handled nearly 17 years ago and our county was and still is very conservative. So although even then, Frederick County had a category called “new and innovative” under which our composting toilets and gray water system were approved, we still had to install redundant traditional system of plumbing both supply and waste, if or when (is what I think the county folks were thinking) our “new and innovative” system failed. So this added to our expense but allowed us to be approved. I think in the nearly two decades that have lapsed since that time, there is more tolerance of “greening up” of systems. The phrases “reducing our impact” and “reducing our carbon footprint” are commonplace today and frankly on everyone’s mind. Therefore these systems have moved closer toward the mainstream current of things. It is a new day …a different time.

      Not sure where you live but the approval process is likely to go more smoothly if your proposal includes using a reputable maker of the composting toilets and designer of the gray water system, such as Clivus Multrum. Doing it this way gives the permit reviewer more confidence that you know what you are doing and in the end the project will be a success and work and save tons of gallons of water.

      Hope this helps.

  2. I live in Frederick County now, and plan to stay, so yes, this was very helpful, thank you! I did find that part of COMAR and will definitely check out Clivus. Thanks again!

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