Composting Toilets, Why to Compost

I say why “to” compost because that is where we need to move towards as a society. Safe composting of human waste is on its way. We in the wastewater industry are, in general, not familiar with composting. It is generally considered to be liquid waste management. That soon will change, presuming that the Ministry of Health’s and ASTTBC’s initiative behind the draft Composting Toilet and Greywater Practice Manual is realized and standards and guidelines are established in B.C. With effective standards and practices, high end compost that is pathogen free and fertile will become common place.

Why compost?  There are many reasons that a person would choose to have a composting toilet, such as:

  1. Cost savings under some conditions.
  2. Site and soil constraints for sewerage system can make it impossible to shoe horn in a conventional system. Having a composting toilet can reduce the soil area required for a field.
  3. Water conservation

Some areas of Cedar in the Nanaimo Regional District, located just south of Nanaimo, have a bylaw that stipulates the use of rainwater for outdoor water use because of concerns of overuse of the groundwater. A compost toilet can help to offset water consumption in areas like this with compromised aquafers.

Cedar used to have a much higher water table but over time, development with its consequent increase in water consumption has lowered the water table to the point where restrictions on water use was required. Considering that east Vancouver Island is the retirement capital of Canada, increasing population will inevitably effect water supply in a diminishing way, for humans as well as for the rest of the ecosystem, such as fish needing water in the creeks in order to return to spawn.

Local urban areas with piped municipal water are also actively promoting water conservation, often imposing water use restrictions. This is a theme that we have watched develop over the last few years. Composting toilets mostly are thought to be a country thing but could be of increasing value in water starved municipal areas. With standards, guidelines, trained practitioners, a growing level of effectiveness and acceptability will develop along with centralized, locally based composting facilities to receive and finish the stabilized compost residuals from individual toilets.

As municipalities grow so does their wastewater plant requirements.  By encouraging and fostering the use of compost toilets, the organic loading to the sewer system can be decreased and extend the life of the system. The other benefit of lowering the organic loading is that with the increased use of greywater for landscape irrigation there is a chance over time that there will not be enough water in the sewer system to flush the solids down; compost toilets will mitigate this potential problem.

  1. Water scarcity, very limited water supply

Some rural properties have seasonal drought, low yielding wells, or no wells and rely on rainwater harvesting. Having a dry toilet goes a long way to make meager supplies last.

  1. No water supply available (common at parks, rest stops)
  2. Reduction of volume and mass of waste, for removal off site

At some remote park locations there is no road access. At the more popular sites there are toilets, the wastes from which, need removing. Helicopter is the only option in many places. Obviously the cost is exorbitant. With composting, the mass can be reduced considerably and thereby reduce the many costs of helicopters.

  1. Marine craft, reducing space for holding tank and increasing the options for discharge as well as water savings
  2. Nutrient reclamation and organic matter recycling,

Commercial agriculture, as practiced for the past many decades, is not sustainable because it depends so heavily on diminishing supplies of fossil fuel and mined fertilizer.  Fertilizer stocks are a finite resource.  For some nutrients it is only a matter of decades before they are no longer available in our part of the world. Some countries are already feeling the pinch as the few companies that control fertilizer production and distribution continue to raise prices as stocks become more depleted. This combined with soil depletion caused by irresponsible farming methods and other forms of development is exposing the world’s food supply to big risks and in some countries is already catastrophic.

In order to offset the threat to our food supply, it is and will over time become more critical to once again recycle our human bodily waste for food production, both in regard to nutrient value and as a soil amendment to rebuild depleted soil. This is happening in some areas already but in Canada not too much attention is paid to this. By establishing strong standards and guidelines now we can start developing protocols and practices that will over time turn the tide on allowing us to become self-sufficient in our food production practices.

Urine too is high in nutrients and can be used in liquid form as a fertilizer or also can be composted. The solids component of urine per capita per day is actually higher than that in feces. This seems counter intuitive but the dissolved solids in urine released in a day contains more solid matter than a person’s feces in a day. It is true that some of this is salt. The phytotoxic effects of salt can be mitigated by combining and mixing with other compost stocks or using the urine with salt tolerant plants.

  1. Remediation potential for failing septic systems

To us in the onsite industry, being able to install a composting toilet in situations with failing septic systems could be a deal breaker where it is not possible to rejuvenate the existing system or there is no available area or suitable soils in which to rebuild. Using a composting toilet would remove most of the organic loading to the failing system, leaving just the greywater to be treated and absorbed. Over the course of a summer this may allow the failing field to rest and become revitalized enough for continuing to receive greywater and leachate from the composter.

If the existing field was irremediable then the new replacement field could be reduced in size because of the composting toilet.

  1. Circumvent new loading and consequent overloading to an existing septic system when adding bedrooms or a guest cabin to an existing house
  2. Reducing soil and water pollution from pharmaceuticals

Research has shown the effectiveness of composting to reduce that fraction of pharmaceuticals found in feces to be substantially reduced by the composting process. Composting of urine would further reduce the likely-hood of these chemicals persisting in the environment.

This may be the most important reason to compost human waste. Many pharmaceutical medications have been shown to persist in the environment. These residuals form cocktails, which, act as hormone mimickers or endocrine disruptors. Fish sampled near the outfall of the city of Vancouver’s sewer system have exhibited the toxic effects of this with some of them showing signs of chemically induced sex change.

These chemical compounds are relatively new in human history. If we persist in using them without regard for the environment then we will surely be complicit in the process of mutation of the natural world.  As an industry it is important that we address this, as we may be the last line of defense.

There are many reasons to use a composting toilet. Currently it is a marginalized practice. With standards and guidelines in place it can start to become more accepted and more effective. Over time the general public as well as the wastewater industry will view it as a viable option and over the longer time we will realize its necessity for a sustainable future.

Ed Hoeppner
ROWP
Planner/Installer

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