Within the next few years, coastal municipalities will be compelled to redesign their wastewater systems in order to meet state-mandated limits on nitrogen loading to sensitive marine environments. The options vary, but many towns are considering laying miles of sewer pipe to replace septic tanks, and upgrading their wastewater treatment facilities, a costly, yet effective way to meet the targets.
While it is understood that the town’s efforts will improve water quality and biological habitat, these benefits may not be realized in our lifetimes, due to the estimated 25-50 years it could take for all the contaminated groundwater to flush through the estuaries. Many residents balk at the $250-600 million price tag, which will likely be financed through betterment fees for homeowners and tax levies for all residents.
A message from Karen Schwalbe of Hatchville sums up the problem and offers a potential solution:
There is an old adage: if you take a barrel of sewage and add a teaspoon of wine, you get a barrel of sewage; if you take a barrel of wine and add a teaspoon of sewage, you get a barrel of sewage… Adding clean (and drinkable) water to human waste, then having to clean up a larger volume seems the wrong way to go. Why aren’t composting toilets or dry toilets being considered as part of the solution to our wastewater problems?
What if there was an option that residents could undertake right now that would remove their household’s contribution to the waste stream? In this blog, we’ll explore some of the innovative ways that people are turning their waste into a resource. It’s not as tricky (or stinky) as one might think…
Amy Larkin shows off her vegetable compost pile
Alchemy Farm in Hatchville, the former home of the New Alchemy Institute, is a place where the traditional meets the modern. A wind turbine from nearby Coonamessett Farm beats under a steady southwest breeze. Houses tucked into the pine trees are adorned with solar panels. Roosters crow and goats bleat.
So it shouldn’t come as a surprise that many of the residents in the neighborhood have something unusual in their bathrooms: composting toilets, a method of collecting human waste and turning it into harmless, useful fertilizer.
Actually, there is nothing unusual about the bathrooms. The Larkin family’s, in particular, smelled faintly of pine shavings. The only noticeable difference in their composting toilet-enhanced bathrooms is the white pipe, which makes a faint whirring sound. And the subtle absence of a flush handle on the toilet.
Compost my… what?
A composting toilet: the only difference is the pipe
As Amy Larkin kindly explained, when someone uses the composting toilet, the waste drops down a tube to a Clivus Multrum storage tank in the basement. The white “stinkpipe,” seen at left, continually pulls air out of the toilet and the storage tank, removing any odors.
The fan in the pipe runs 24/7, but is powered by solar panels, which operate even if there is a power outage. Amy often cleans the fan and has replaced it twice in the toilet’s 11 years of operation. “If that fan goes, the whole house smells,” she said.
Occasionally, a user will throw some sawdust or wood shavings (in the bucket to the right) into the toilet, which helps promote the texture, aeration, and moisture of the compost.
At a cost of $6,000 to install two toilets (including labor for two men and one plumber), the composting toilets are not nearly as expensive as a sewer connection, and probably rival the cost of regular home plumbing systems. After jumping through a few hoops with the Board of Health and building department, they installed one of the first composting systems in Falmouth. Their neighbors soon followed suit.
The Larkins had enough foresight to install their composting system when they built their house 11 years ago. It would be more difficult, but not impossible, to remodel a typical Cape-style house to include one. As Amy’s husband, Jonathan, pointed out, “the limiting factor is gravity”: their house is designed around their 1st and 2nd floor bathrooms, which must be located directly over each other and the storage tank.
“That’s what we got, a two-story outhouse,” Amy said.
Muckraking can be fun
Fresh compost, straight from the chute
A composting system requires some maintenance, Amy said, but it has become part of her regular household chores to ensure the pipe is clear and aerate the compost with a rake. She estimates that she removes about 20 gallons from the tank every few months.
“I actually like it. It bothers me more to put sewage into clean water,” she said. “But it’s not for everyone. You have to be a little earthy.”
In the initial “mineralizing” phase, the waste is doused with fresh water. The liquid is then pumped out into a separate storage tank. Aerobic bacteria and fungi break down the nitrogen in urea (the primary component of urine) into ammonia and carbon dioxide. As it passes through the compost mass, nearly all of the ammonia is converted, first to nitrites, and then to nitrates by nitrifying bacteria.
Good vs. bad bacteria
The holding tank of a Clivus composting toilet
Human pathogens are killed not by the heat within this “mouldering” composter, but by predatory organisms and the retention time they spend in the system. Phosphorous and potassium, along with a wide range of micro-nutrients, are also captured by the composting process.
According to the manufacturer, the compost liquid results is a stable, high-strength fertilizer. Fecal matter in the compost system is reduced in volume by more than 90%. When fully composted, this material looks and smells like topsoil, and is an organically rich soil amendment.
The Larkin’s system does not include red worms, but those may be added to the holding tank to transport oxygen and moisture throughout the compost mass, thus assisting the physical and chemical breakdown. Thermophllic composting systems rely on temperatures of 25-40 °C (77-104°F) to fully break down the pathogens, assisted by beneficial bacteria.
Ecological fertilizer
The remaining compost mass is supposed to be hauled away by a septage hauler, but if that step does not take into account the beneficial properties of adding the composted material to a vegetable-scrap compost pile to use as fertilizer. It also does nothing to remove nitrogen from our community’s wastewater stream. By letting soil and plants around your house absorb the nitrogen, phosphorus, and micro-nutrients, the “solution to pollution is dilution” adage is put to work.
Toilet compost may not be something you would put on your vegetable garden, but as the Larkin’s neighbors, Earl and Hilde Maingay said, “bury it 8 inches under a tree and see how well it grows.” In fact, the manufacturer advertises its composter as a way to produce a home-grown, organic fertilizer, instead of buying the energy- and chemical-intensive commercial brands, which are often made from the very same substances we flush down the toilet.
Tags: Alchemy Farm, composting toilets, fertilizer, nitrogen, Woods Hole Oceanographic Institution
The views and opinions in the Enterprise blogs are those of the author and are not neccessarily shared by Falmouth Publishing.
I like the idea of using what there already is to fertilizer and add nutrients back to the earth, but I admit I’m still a little unenthusiastic about doing the same thing myself, though I compost kitchen scraps on a regular basis. Plant and Garden Blog
I’ve often felt odd trucking dirt in from elsewhere. For folks that have municipal wastewater treatment, I wonder if when they buy topsoil, they’re buying back some of the waste that originated from their own homes. It seems like many households here on the cape could make their own “good” soil and cut out the middle stuff. Your blood, sweat and tears are already in those fabulous heirloom tomatoes. Why stop there?
Make that heirloom ROSES. No food!
The waste is not doused with fresh water.
Nice article Elise!
[...] Turning Waste Into Compost Categories [...]
[...] eco-toilet advocates, the solution to nutrient management lies in closing the loop between waste and [...]