Are we flushing money down the toilet?

As someone who goes to a fair share of wastewater-related meetings, I wasn’t expecting to be blown away at last weekend’s Eco-Toilet Summit.

On a conceptual level, I felt I already understood the basics of composting human waste— hey, I do it every day with food scraps.

Adding one step through my digestive system to my garden seemed to make sense… from a theoretical point of view.

But after hearing about the range of eco-toilet options available, and a variety of perspectives from regular residents, the theoretical became possible.

What stopped making sense is the way we use—and view—the bathroom.

Saturday’s Eco-Toilet Summit was a one-stop shop for those interested in reducing household water use and recovering nutrients from our excretia to make fertilizer to grow food.

A mid-size Phoenix composting toilet

Curious residents flocked to the shrines of ecological design—a large blue Phoenix composting toilet, the Ecovita’s familiar white bowl with a tiny hole for urine diversion, and the diminutive, portable Pacto toilet—and took advantage of the friendly sales representatives to ask questions:

How do they work? Does it smell? How much would it cost to install?

Sponsored by a coalition of grassroots environmental groups, the afternoon was dedicated to learning more about modern ecological approaches to dealing with an age-old problem: how and where to dispose of our waste?

That is the $600 million question, as Falmouth considers ways to clean up decades of nitrogen loading to sensitive coastal embayments, and one which the summit’s sponsors hope can be answered with alternatives to centralized sewering.

I know. Maybe not everyone’s cup of tea. But for anyone who poops and pees, it might be worth it to hold your nose and pay attention.

Eco-logical justice

The go-to solution for the past several decades has been centralized sewering, which collects sewage, storm water, and graywater (laundry, shower, and dish water) in a network of underground pipes for treatment and eventual release back into the groundwater.

I won’t get into all the pro’s and con’s of sewering here, suffice to say that there are two factions of environmentalists doing battle in town: biologists who favor sewers as a proven way to keep nutrients out of the groundwater; and ecologists who view the cycle of nutrients as a “closed-loop” system and favor composting to pump n’ treat.

It’s a fascinating chapter in environmental history, as we discover how we are all responsible for the decline of eel grass and shellfish in our beloved harbors.

The debate also takes on an environmental justice perspective, as one considers the economic cost-benefits of sewering vs. composting or diverting our waste.

Eco-toilet panelists Abe Noe (Phoenix), Carol Steinfeld (Ecovita), Hilde Maingay (the Green Center) and former state rep Matt Patrick

For eco-toilet advocates, the solution to nutrient management lies in closing the loop between waste and resources.

With urine-diverting and composting toilets, the waste products are collected and pumped out roughly every six months, depending on the size of the household. With a compacting toilet, waste is packaged neatly into a plastic or biodegradable bag, which can be collected for compost or thrown out weekly with the garbage, just like regular diapers.

Storage from six months (for urine) to two years (for solids) removes pathogens from the waste, a process that may also break down pharmaceuticals and contaminants of concern.

A composting toilet or urine-diverting system takes advantage of biological processes to break down the nutrients in urine and feces to create potent fertilizer and carbon-rich humus, said Don Mills, a sales manager for the Lawrence-based compost toilet vendor Clivus Multrum.

A conventional wastewater treatment system uses the same process, but combines household waste with stormwater, requiring enormous amounts of energy to pump and adding heavy metals and pollutants to the mix.

Earle Barnhart, whose Green Center organization was the primary sponsor of the summit, noted that treating human waste as a resource could lead to the development of new industries. Whether collected and processed on-site or elsewhere, the compost and fertilizer could be sold and used to grow organic produce, he said.

Dollars and sense

For former state representative Matt  Patrick, the eco-toilet alternative would save residents millions in betterments and taxes to finance the sewer system. Going the sewer route, he warned, could force middle- and low-income residents to leave town.

I don’t think any of us want to live in a community that’s all wealthy, where middle class and low-income families can’t afford to live. But that might be one of the outcomes if we press forward with a conventional sewer system.

-Matt Patrick

According to Mr. Patrick, installing two urine diverting toilets in every home in the south coast watershed would amount to just 10% of the cost of sewering those neighborhoods.

(2 UD toilets + 2 UD urinals @ $1,500-$3,000/home)                    x 8,000 homes = $12-24 million

+ $175/year pump-out  x 8,000 homes = $1.4 million

x 10 years= $14 million

Grand total cost for 10 years installation & maintenance:

$26-38 million.

Not only would about 80 percent of the nitrogen currently leaching from septics be stopped in its tracks, but local plumbers and waste service industries would be employed by this system, Mr. Patrick said.

The cost for each alternative system varies depending on household needs, but the vendors estimated about $1,000 for a micro-flush urine-diverting toilet; about $1,100 for a compacting toilet, plus $200 a year for disposable bags; and up to $6,000 for a large composting toilet, not including installation and maintenance.

A three- to 12-watt fan is required to remove odors from the composting system, but Mr. Patrick noted that the electricity cost for such a system is less than one energy-saving light bulb.

The Falmouth precedent

One of the recurring questions from the audience was whether this innovative method of handling waste had been done elsewhere.

Mr. Patrick said that UD toilets are popular in Sweden. Don Mills of Clivus Multrum pointed out that Europeans, Americans, and Asians only stopped using “night soil” as fertilizer in the last century.

I might add that Africans are also composting their waste, providing low-cost sanitation as well as bananas, a source of food and income.

Hilde Maingay, of The Green Center, makes the case for eco-toilets as a means of achieving social justice

Faced with an almost overwhelming dilemma, Falmouth has a unique opportunity to set a precedent among coastal communities. Yes, it is scary to be the guinea pig—but how appropriate, given our world-renowned science community and ecological pioneer residents.

Money is relative to social justice and long-term stability. [Eco-toilets] could add more stability to communities and make them more socially just.

-Hilde Maingay, the Green Center

The Eco-Toilet Summit organizers are not expecting anyone to just take their word for it, however.

They are hoping for a study of these alternative systems, including an energy-use cost-comparison with a conventional system and the regulatory mechanism by which residents could install (and maybe even get loans for) an eco-toilet system of their choice.

The cost-benefit

Mr. Patrick is in favor of urine-diverting toilets, which sequester the high nitrogen content in urine while using small amounts of water to flush feces into a septic system.

He’s a fan because of the relatively low cost and high nutrient recovery. Given that the system only needs to be pumped periodically, the maintenance requirements are also pretty low.

Composting toilets are already approved by the Department of Environmental Protection and are widely used in Massachusetts, but urine-diverting toilets have yet to go through the permitting process.

While the jury is still out as to whether composting waste will remove the pharmaceuticals and other harmful chemicals, eco-toilet proponents make a good point that it is better to remove those “contaminants of concern” from the waste stream altogether, rather than combine them for centralized treatment.

Currently, most wastewater treatment plants lack the technology to remove the aspirin, caffeine, hormones, and pesticides from effluent anyway.

Even with an eco-toilet, septic systems would still be required to handle the household laundry, bathing, and dishwater, also known as graywater. The pollutants associated with those systems would not be addressed by an alternative toilet system either.

I’ve written at length about UD toilets, composting and compacting systems elsewhere on Under the Lens, so please click here if you are interested in the details.

Footnote: it’s in the report

For further reading, it’s interesting to note that Stearns & Wheler, the engineering design firm that developed a draft of Falmouth’s comprehensive wastewater management system, devoted a few pages to “waterless toilets” and UD systems in its 454-page report.

a. Wastewater flows and loads are reduced if properly designed and installed.

b. Water consumption is significantly reduced.

c. Minimal environmental concerns occur when properly sited and designed.

d. Composting toilets require minimal energy use.

e. Size of standard septic system can be reduced to treat only gray wastewater.

f. Routine maintenance is minimal and requires no special training.

As for urine diverting toilets, Stearns & Wheler lists the advantages:

a. Water consumption is reduced.
b. Minimal environmental concerns occur when properly sited and designed.
c. The nutrients in the urine could be positively recirculated in the environment by use as fertilizers.
d. The technology could decrease the nutrient removal costs associated with wastewater (less the urine component) at the WWTF.

Urine source separation toilets have the following disadvantages, according to Stearns & Wheler.

a. Existing biological and chemical technologies at WWTFs are not sufficient to treat concentrated urine. Additional facilities would need to be designed and constructed.
b. Homeowner renovation costs would include new toilets, plumbing, and urine storage facilities. Urine separating toilets are likely to be costly and lack decorative design options which may decrease homeowner acceptance.
c. Increased homeowner disposal hauling costs associated with two separate collection systems.
d. Septage hauling trucks may need retrofitted equipment to properly handle concentrated urine.
e. Technology works correctly with proper use. Proper use is limited to sitting on the toilet, meaning behavior modification for males.
f. Technology works correctly with proper maintenance, which includes removing urine scale that can block pipes over time and using certain cleaning agents which would not contaminate the collection tank.
g. Human urine use as an agricultural fertilizer may not be socially acceptable.
h. Not well suited to high seasonal community and tourist population.