This week we are featuring an exceedingly informative post by Gingerhill’s newest contributor, Sarah Montano! The composting toilet is a valuable tool for any one looking to learn more about how to go green. Our composting toilet is helping us move beyond sustainable agriculture toward regenerative agriculture.

Using a flush toilet inevitably creates unnecessary waste. Conventional toilets use clean water to carry away human waste, creating pollution every time we flush. In using a compost toilet, we are creating a valuable resource, transforming human biological waste, or ‘humanure,’ into compost. Doing so allows us to generate fertility by delivering nutrients to the trees on the land. If you are looking to learn more about how to go green in a cost-effective manner, this post is a must-read!

A Composting Toilet Is:

-A system in which the continuous composting of humanure takes place. In time, the system creates humus: a nutrient dense, harmonious community of living microorganisms.

-A successful composting toilet is entirely self-contained. Thus, there is no risk of pathogens passing from the toilet into the ground or surrounding area, even in the event of heavy rain and storms. A composting toilet is therefore a valuable tool in regenerative agriculture because it produces yield by converting solid waste, toilet paper, and sawdust into compost.

The Benefits of a Compost Toilet

  • Saves clean water: A conventional toilet generates an average of 6 liters of clean water in a single flush. About 50 liters (13 gallons) of clean water per person are flushed away each day. 
  • Creates no waste: Organic refuse becomes nutrient dense compost that supports the growth and resilience of plants. What better advice on how to go green is there than to implement waste-free waste management?
  • Reduces reliance on non-renewable energy: Waste-disposal plants and systems rely on fossil fuels and toxic chemicals to transport, process, and dispose of sewage. A composting toilet does not require transporting waste off site. Sawdust or another organic source of carbon is the only additional input necessary for decomposition to take place. Furthermore, the final product is non-toxic.
  • Saves money: Using a composting toilet reduces water usage, thereby lowering water bills and waste-disposal costs. Once the structure for the composting toilet is built and paid for, it requires very little upkeep. In fact, it can last decades if well-cared for. At Gingerhill Farm, the composting toilet successfully serves a community of eight with daily use and requires zero water to operate. About every 12 months we are able to harvest a batch of compost to amend soil and support the fertility of the land. Doing so brings value to the farm by promoting abundance in fruit trees and hardwoods.
  • Prevents pollution: A compost toilet reduces or eliminates sewage in septic tanks, cesspools, and municipal processing plants, thereby preventing pollution. Thermophilic composting masses, such as the composting toilet, can destroy human, plant and animal pathogens during the natural biological process of decomposition.

The Four Phases of the Composting Toilet Process

A composting toilet is a continuous system where input is added, a little at a time, until the tank is full. There are four phases in the composting toilet process.

Phase One

The first phase of the composting process is the Mesophilic Phase. During this initial phase, a composting mass reaches temperatures ranging from 68℉-113℉. Organic refuse such as feces or food scraps combined with carbon such as sawdust or dry leaves in a contained area create an environment in which biological decomposition can take place. Naturally occurring compost bacteria consume carbon and oxygen to produce carbon dioxide and energy. Bacteria then use this energy to grow and reproduce. Finally, excess energy escapes as heat. Under these conditions, the mesophilic bacteria begin to flourish, raising the temperature of the composting mass to a maximum of 111℉.

Phase Two

The Thermophilic Phase begins when a composting mass reaches temperatures of 113℉ or higher. The metabolic processes of the beneficial microbes release energy, thereby creating a thermophilic environment. In this environment, high temperatures destroy any dangerous bacteria as beneficial, heat-loving bacteria take over. Thermophilic bacteria thrive in temperatures above 113℉. They are some of the oldest organisms on the planet at 3.6 billion years old. When thermophilic bacteria such as those from the genus Bacillus take over, they inhibit the growth of mesophilic bacteria such as E.Coli.

The thermophilic phase takes place rather quickly and may last a few days to a few months. Some composting systems have a stacking function design wherein a secondary system compliments the composting system. This design captures resources like heat and methane that the composting process generates. For example, a composting manure pile built around copper plumbing can also serves as a radiant heater.

Phase Three

The third stage in the composting process is the Cooling Phase. During the cooling phase, the humanure may have been converted to compost. However, beneficial insects like black soldier fly larvae, fungi, and mesophilic bacteria will need to digest the larger, coarser material like toilet paper and wood chips. These microbes will return to the chamber as it cools.

Once the toilet chamber is full, we close it, allowing it to cool and complete the decomposition process. Then we typically leave it for about 365 days. Eventually the closed toilet chamber enters the final phase.

Phase Four

The fourth and final step in the humanure composting process is the Curing Phase. The curing phase should be allowed at least 365 days to complete. Human pathogens and phytotoxins expire during this time as other beneficial microbes take over. Compost in its final stage is free of pathogens and plant seeds, and it’s neutral in smell. While the first toilet chamber is completing the curing phase, we utilize the second toilet chamber. After compost has completed the curing phase, we can mix it with dirt and apply it to fruit trees and hardwood trees.

How A Composting Toilet Works

At Gingerhill Farm, the composting toilet is part of a stand-alone bathroom design that includes the composting toilet room, a separate wash-room with two sinks, a changing room, and an open-air shower. The toilet room has a two-chamber composting system. There are two toilets, but only one is in use at a time. The toilet room is built atop a large concrete chamber of three solid walls and a concrete floor. The back wall of the chamber has wooden planks that can be removed come time to harvest the cured compost.

First we prepare the chamber for the active toilet by creating a thick base layer of organic, carbon-rich material. We typically use wood chips, which act as a sponge for moisture that travels to the base of the toilet. Then we use the active toilet by depositing only solid waste and toilet paper. Finally, we cover the waste with a layer of dry sawdust. It is essential that only solid waste goes into the toilet.

The Role of Microorganisms

Microorganism that live in the compost pile, which include bacteria, fungi, and actinomycetes, need carbon. These organisms utilize this vital element as a source of energy and as a building block for living and reproducing. They also require nitrogen, but only in small amounts, to create cell structure, genetic material, and proteins.

Beneficial microorganisms thrive in a compost pile with a carbon to nitrogen ratio of 30:1. Human urine is about 15% nitrogen, with a carbon to nitrogen ratio of 0.8. Excessive urination in a composting toilet will result in the creation of smelly ammonia gas. Thus, at Gingerhill Farm, people are encouraged to urinate outside under trees to deliver valuable nitrogen to the plants.  Although urine is sterile when it leaves the body, it is important to keep it away from vegetables; the high levels of nitrogen will damage the plant.

Objections to the Composting Toilet

In western culture, waste management has long been the task of municipalities and private industries. Thus, people may naturally have some concerns about the safety of the composting toilet. After all, most of us have not had to learn how to deal with our waste.

Here are some common objections to the use of the composting toilet:

Is human fecal waste dangerous? 

In it’s raw form, feces has the potential to carry pathogens. However, in a composting toilet, human feces is an input, not the final product. During the Four Phases in the Composting Toilet Process, a complex scientific reaction occurs wherein beneficial microbes digest feces, breeding more beneficial, naturally occurring microbes. These microbes out-compete the short-lived pathogens. The process creates a hot environment in which only thermophilic bacteria & fungi can live. Most pathogens do not survive the mesophilic phase. after 365 days in the curing phase, all feces has been converted to humus.

Isn’t a composting toilet foul-smelling? 

A composting toilet should be neutral in smell if you use it correctly. A composting toilet is not a magic box that converts our waste into compost. It is a tool that requires proper methodology and science to work efficiently. Urinating excessively into the compost toilet will result in off-gassing of nitrogen and, by extension, an unpleasant ammonia smell.

A sufficient ratio of carbon to nitrogen is necessary for composting to occur. 30 parts carbon to 1 part nitrogen is a good rule to follow. You must therefore always be sure to use enough sawdust after each deposit. This allows for the composting process to occur. It also aerates the composting mass so that beneficial microorganisms in the pile have access to the oxygen they require. Proper aeration allows these microorganisms to aerobically convert carbon to carbon dioxide. Foul-smelling methane is produced in an anaerobic environment, so be sure to create proper layering in the composting chamber.

How To Go Green: Composting, The Life Cycle, and Conscientious Living

Now, consider a farm that captures solar energy and stores the energy by growing vegetables. The vegetables leave the farm. Humans eat and digest the vegetables. Eventually, they defecate into a flush-toilet. In this story, where are the energy from the sun and the nutrients from the soil going? Some of the solar energy and nutrients become the human. The rest are passed as feces, flushed away as toxic waste for a waste-isolation plant to deal with. These plants use incredible amounts of energy, water, and chemicals.

The composting toilet is a symbol of humble yet conscientious living. By caring for the land, growing fruits and vegetables, sharing nourishing meals, making a deposit into the composting toilet, and tending to the composting toilet processes, we are participating in a practice that sustains the fertility of the land and the health of its inhabitants.

By encouraging others to consider moving away from wasteful methods and systems, we are making strides in becoming a regenerative community. We invite you to visit Gingerhill Farm for a farm tour. There you can see (and use) the composting toilet design, and enjoy the vegetable gardens and the orchards. We also have two lovely cabins available if you are visiting the island and would like to enjoy a relaxing and vibrant place to stay where you have the option to use either a flush toilet or donate some material to the composting toilet.


The Humanure Handbook, Joseph Jenkins

I recommend this book if you want to learn more about composting toilet systems. Jenkins details the scientific processes of the composting toilet and extensively covers methods and resources for composting humanure. He also covers concerns such as, what happens to antibiotics and prescription medications that humans pass in their waste?

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