A typical urine-diverting toilet collects solid and liquid waste, which could be processed into fertilizer, removing nitrogen from the waste stream

Considering that we all flush at least three times a day, it’s surprising how little we know about where our waste goes. Into a white bowl and then down a pipe— never to be seen, smelled, or thought of again.

But as many Cape Codders are beginning to realize, that’s not really the case. The by-products of our waste are seeping out of underground septic systems and into the groundwater, flowing finally into coastal ponds. The nutrients are harmless by themselves, but in concentrated form, throw off the ecological balance of sensitive estuarine systems.

Though there are many nutrients and “contaminants of concern” to be worried about, nitrogen is known as the culprit for changing pristine harbors into algae-filled swamps, devoid of marine life. Or so we fear.

Last night, Falmouth selectmen approved a town-wide comprehensive wastewater management plan (CWMP), developed over the course of several months last year by a panel of community members. It calls for over $300 million to install a sewer system in the neighborhoods south of Route 28 from Little Pond to Seapit Peninsula. Millions more are expected to sewer the next phases north of Route 28.

The CWMP committee and selectmen also set aside funding for the study of alternatives to sewering, which could lower the overall cost of the plan.

Several of these options were covered in a forum held earlier this month at the Waquoit Bay National Estuarine Research Reserve (WBNERR), in which four experts in various areas of wastewater treatment delivered “The Scoop on the Poop” from the perspective of traditional sewer systems, alternative systems, shellfish aquaculture, and coastal engineering.

It’s not as complicated as it sounds. In fact, it should be taught in grade schools.

The big pipe method

Falmouth's wastewater treatment plant on Blacksmith Shop Road is one of just five such facilities on Cape Cod

Michael Giggey, the senior vice president of Wright-Pierce, an engineering and consulting firm, started off the evening with an overview of the municipal treatment options, from individual “on-site” systems to cluster and satellite systems to centralized wastewater treatment facilities.

As an advisor to the Town of Orleans on its comprehensive wastewater management plan and an islandwide wastewater plan on Martha’s Vineyard, Mr. Giggey noted that each watershed has different needs, which can be met through a combination of technologies.

The simplest option, he pointed out, is to simply eliminate the main controllable source of nitrogen pollution by removing enough septic tanks to meet the TMDL and connecting those homes to a sewer system, discharging the treated effluent outside the watershed.

However, across the Cape, that strategy has proven to not be so simple, and certainly is not cheap.

In Falmouth alone, the cost of sewering homes south of Route 28 from Little Pond to Seapit Peninsula is expected to cost $310 million for the first two phases, to be paid for by a combination of taxes and homeowner betterments. Across the Cape and Islands, these figures add up to billions.

In a report compiled last April by the Barnstable County Wastewater Cost Task Force, the study found the most important factor when choosing a wastewater treatment strategy is the amount of nitrogen that each system can remove per dollar spent. Centralized wastewater treatment facilities can reduce nitrogen down to 3 milligrams per liter, whereas effluent from on-site denitrifying systems ranges from 10 to 19 mg/L, Mr. Giggey said.

Though sewer mains and wastewater treatment facilities require a large amount of capital up front, the task force found that operation and maintenance costs for a centralized sewer system were far lower than on-site denitrifying systems, cluster, or satellite systems.

“It’s not just about cost, but cost-effectiveness,” said Mr. Giggey, who served on the task force. “It would seem the most cost-effective option is with the larger systems.”

David Dow, president of the Cape and Islands chapter of the Sierra Club, asked Mr. Giggey whether wastewater managers on Cape Cod have had any experience with removing “contaminants of concern” from effluent. These chemicals are the byproducts of pharmaceuticals, personal care products, and detergents that most wastewater systems do not treat, or even monitor.

“Unfortunately, there’s not a lot of local experience. We’re just now getting our arms around what nitrogen does. Contaminants of concern are not just one compound, it’s thousands,” Mr. Giggey said.

Innovative & Alternative systems

The British-designed "Loowatt" toilet was originally built with the waste disposal needs of developing countries in mind.

Also serving on the task force was panelist George Heufelder, director of the Barnstable County Department of Health and the Environment, who established the Massachusetts Alternative Septic System Test Center at the Massachusetts Military Reservation in 1999.

Mr. Heufelder noted that every wastewater treatment option works on basically the same principle: to “manipulate the nitrogen cycle inside a black box.” Though some methods are more efficient than others, the basic idea is to break down nitrates into nitrogen gas, a major component of the air we breathe.

In over a decade of testing, Mr. Heufelder found that innovative and alternative (I/A) systems “remove about 50 percent of the nitrogen 70 percent of the time.”

Emerging membrane technologies, such as the Nitrex, is capable of removing 90 percent of nitrogen from groundwater. The Nitrex, which Mr. Heufelder referred to as “a box of proprietary cellulose material, otherwise known as wood chips,” and other membrane systems are also becoming cheaper and easier to maintain.

A composting toilet: the only difference is the pipe

Another affordable and effective option for individual homeowners is the composting toilet, which Mr. Heufelder noted has an added benefit of separating toilet waste from graywater—the shower, sink, and dishwasher water that usually goes down the drain.

In an earlier comment from North Falmouth resident Alison Robb about the need to keep drinking water from becoming wastewater, Mr. Heufeulder agreed that the tradition of defecating into potable water “is lunacy, but we do it.”

However, he said it would probably require “mass hypnosis” to get every resident to install a composting toilet and never put kitchen scraps or chemicals down the drain. Even if Town Meeting members bought into composting toilets as a nitrogen management strategy, the Department of Environmental Protection would need a way to ensure its regulations were being met, he said.

“It’s trust and verify. Not everyone’s composting nicely in the back yard. There will be some nitrogen [in the system], and we need to know what it is,” said Mr. Heufelder.

The Eco-flush urine diverting toilet can remove 90% of the nitrogen from human waste, using 80% less water than a traditional toilet

Another innovative home nitrogen removal method on the market is the urine-diverting toilet, which was on display at WBNERR, thanks to Conrad Geyser, president of Cotuit Solar.

Though Mr. Heufelder admitted that he and other men might have a problem sitting down to use the toilet, he said one day the market for phosphorus and nitrogen would put a premium on mankind’s most abundant waste product.

Because urine contains up to 90 percent of the nitrogen and 50 percent of the phosphorus in domestic wastewater, separating and collecting it is also a simple way to prevent nutrients from reaching the groundwater.

“I envision a day when someone comes to your door to write you a check for good-quality urine,” Mr. Heufelder said, estimating that there is a total of 150 more years of phosphorus left in traditional mines.

Mr. Heufelder noted that membrane systems can be “a little power hungry,” using five to eight kilowatt hours per day in a typical home. However, the Nitrex makes use of a trickling system with lower energy use, he said.

There are other costs associated with on-site systems that should be factored into their overall costs, said Mr. Heufelder, estimating that one full-time employee would be required for every 1,500 on-site systems to ensure they meet environmental standards.

Furthermore, homeowners are required by regulations to have a maintenance contract for their on-site system, and any residual waste would have to be disposed or converted into fertilizer by a private company, he said.

“I cannot imagine DEP allowing composting or urine-diverting toilets unless the residuals leave the watershed completely,” he said.

The shellfish solution

The Sippewissett oyster, a product of local aquaculture efforts

While town officials and residents tend to focus on technical solutions for wastewater treatment, local scientists are turning to Mother Nature to help reduce the nitrogen load.

Diane Murphy, an aquaculture and fisheries specialist for the WHOI Sea Grant and Cape Cod Cooperative Extension, gave an overview of the potential for shellfish aquaculture to remove nitrogen from sensitive coastal embayments.

While shellfish are becoming more accepted as a method for meeting total maximum nitrogen loads (TMDLs), Ms. Murphy emphasized that aquaculture should not be considered the only solution for reducing nitrogen loads.

“Oysters can serve a crucial role in the uptake of nitrogen. Aquaculture should not be the sole source, but should be integrated into a nitrogen management plan,” she said.

Acting as grazers on the sea floor, oysters and other shellfish consume the phytoplankton that tend to grow in the presence of elevated nitrogen levels. The more food there is, the more the oysters grow.

Though there are conflicting reports on how much water oysters are capable of filtering each day, the accepted number is about 20 gallons per day, Ms. Murphy said. Studies have found that a market-size oyster can sequester an average of 0.52 grams of nitrogen and 0.16 grams of phosphorus over its lifetime.

When harvested, all that nitrogen is removed from the ecosystem “free of charge,” she said.

Based on a study of the 2006 oyster harvest in Wellfleet, Ms. Murphy said that 20,000 bushels of oysters can assimilate 282 kilograms of nitrogen. The oyster feces become buried in the sediment, stimulating denitrifying bacteria, a process that results in nitrogen gas being released to the atmosphere. In Wellfleet that year the total nitrogen removed was 2.3 tons.

Even though oysters are good to eat, Ms. Murphy does not advocate turning every coastal pond into an aquaculture site, noting the impact on recreational users’ access to and enjoyment of the water.

A large-scale oyster aquaculture project could clean up Falmouth's coastal ponds, create jobs and increase local food production

About 2.5 million oysters would be needed to filter all the water in Waquoit Bay, Ms. Murphy said, requiring about 10,000 square meters, or about 2.5 acres, for all of the gear.

According to an estimate by Woods Hole resident and aquaculture consultant Ron Zweig, many more oysters may be necessary to adequately filter the water, covering up to 30 acres of the 825-acre bay.

The ecosystem also has a certain “carrying capacity” for aquaculture production, and even oysters have their limits before disease, predation, and lack of food inhibit their growth, she said. Because each estuary is different, she recommended a feasibility study to determine how extensive an aquaculture operation the ecosystem is capable of supporting.

Mashpee Shellfish Constable Rick York. said that conditions in the estuary also determine the type of shellfish most suitable for aquaculture. In the low salinity of the Mashpee River, he had great success in growing half a million oysters without fear of predation or disease. Since 2005, the oysters have removed over a ton of nitrogen, he said, which increased the dissolved oxygen content to the point of being safe again for fish.

However, he said the Mashpee River is unique, and in other areas he would recommend seeding quahogs instead of oysters.

“I take issue with oysters having the most potential,” he said. “Quahogs don’t filter as much water, but they consume as much nutrient.”

Flushing the bays

Another strategy to decrease the impacts of nitrogen in sensitive embayments is to increase the amount of “flushing,” or exchange, between the ocean and the estuary.

Nitrogen concentration is higher at the head of coastal ponds, but becomes diluted in areas of greater flushing

The adage, “the solution to pollution is dilution” rings true in this case, said John Ramsey, a senior coastal engineer at Applied Coastal Research and Engineering, a Mashpee firm.

If the tidal conditions are right, nitrogen concentrations can be decreased to acceptable levels, even if the load remains high, he said. Since people tend to live near the water, the nitrogen load at the head of the bay tends to be higher than that near the tidewater.

Due to coastal geology, estuary inlets tend to become filled with sand, or even become blocked by the formation of barrier beaches, he said, showing slides of such events. Unless the inlets are dredged, flushing will decrease over time, Mr. Ramsey said.

Even if the inlets are maintained, all tides are not created equal. While Cape Cod Bay has a 13-foot tide, Vineyard Sound only has a 1.5-foot fluctuation, and Buzzards Bay tides are about 4.5 feet.

“The size of the pump matters,” Mr. Ramsey said. Some towns, he said, “are at a huge disadvantage for tidal flushing.”

Green Pond, Bournes Pond, and Eel Pond in East Falmouth

In Falmouth, Bournes Pond has been cited as one area that does get a generous amount of flushing activity. Mr. Ramsey said if the inlet could be widened from 50 to 100 feet, the coastal pond’s nitrogen concentration would be reduced from 0.6 milligrams per liter to 0.46 mg/L. That reduction would mean that half as many homes in the Bournes Pond watershed would have to be connected to a sewer, he said.

Although on paper widening the inlet seems like a win-win solution, wetland protection regulations place restrictions on projects of this kind because of the impacts on barrier beaches, which protect coastal zones from storms and flooding and provide habitat for endangered species, said Mr. Ramsey.

“Widening the Bournes Pond inlet will create a bigger footprint of impact on the barrier beach system. It’s something regulators will struggle with,” he said.

Earle Barnhart and Hilde Maingay, whose nonprofit organization, The Green Center, is the successor to the New Alchemy Institute, is concerned that the “big pipe” solutions being discussed by a town committee are inefficient and expensive ways to reduce nitrogen loading to Falmouth’s coastal ponds.

The husband and wife team have compiled nine options that residents can undertake to eliminate nutrients from wastewater. They suggest that a feasibility study be conducted to see how much nitrogen would be eliminated, and at what cost, under each scenario.
“With a great variety of options available right now, home-based systems can be designed to respond to the specific needs of each individual residence or area of concern, require very little design time or costs, can be installed immediately, and have a great degree of inherent flexibility,” wrote the couple in a five-page handout they e-mailed yesterday to Town Meeting members.

• Residents can reduce their nitrogen contribution by using low-nitrogen and phosphorus-free soaps, cleaners, and detergents.
• Eliminating the use of chemical fertilizers and garbage disposals would also reduce the amount of nitrogen in the waste stream.
• Noting that car exhaust and road runoff is a significant source of nitrogen deposition to estuaries, residents can reduce their mileage or switch to a hybrid vehicle.
• On a townwide level,  Falmouth could collect food waste separately from garbage to make compost, thereby using the nitrogen and other nutrients in food as fertilizer.

For those who think it is too hard to incorporate these tips into their lives, Hilde and Earle are living examples. They own a composting toilet, which they say is inexpensive and easy to maintain. As professional landscapers, they use compost and organic fertilizers, and at home they feed food scraps to their chickens and use plant-based cleaning products.

The Bigger Picture

A large-scale oyster aquaculture project could clean up Falmouth's coastal ponds, create jobs and increase local food production

Drawing from the expertise of farmer and aquaculture researcher Ronald J. Smolowitz and Woods Hole resident Ronald D. Zweig, an aquaculture specialist for the World Bank, Hilde and Earle recommend using oysters as  natural filters for nitrogen, and widening the inlets of coastal ponds to increase tidal exchange.

A centralized sewer system, while effective at removing nitrogen, comes with a high cost and long lead time to design, construct, and operate, the authors wrote. In terms of water and energy consumption, it is also inefficient.

Purifying water for drinking, then polluting it with human waste, and cleaning it again is inefficient. Transporting large volumes of water from a supply source to a pumping station, to homes, to a sewage treatment plant, and finally to a discharge area is inefficient.

A variety of sources contribute nitrogen to groundwater, but a majority leaches from underground septic tanks

If wastewater treatment was viewed as a “closed-loop” system, the nutrients it contains could be recovered, treated, and used as organic fertilizer, say Hilde and Earle.

Composting toilets

A composting toilet: the only difference is the pipe

The waterless composting toilet is one of the options Hilde and Earle propose for further study.

It looks like a regular toilet, without a pipe. A fan ensures that odors are released through a pipe in the roof, requiring as much energy as a 60-watt bulb.

“The lower the technology, the less likely it is to fail,” said Hilde.

“That’s right,” said Earle. “Gravity never breaks down.”

The holding tank of a Clivus composting toilet

Collection requires a basement storage tank for solid waste, which is typically removed four times a year.

Though current health codes require off-site disposal, the sterilized waste could be used as commercial fertilizer or at home for non-food crops.

Urine-diverting & packaging toilets

Another option is a urine-diverting toilet with an optional waterless urinal.

With this technology, naturally sterile urine is collected in a basement storage unit, where it can be collected for fertilizer, or be processed in a septic or sewer system.

Hilde and Earle also propose a few options for using waterless packaging toilets and urinals. These options would require a commercial contractor to collect waste “packets,” which can be sterilized and composted to create fertilizer.

The British-designed "Loowatt" toilet was originally built with the waste disposal needs of developing countries in mind.

Alternatively, the packets may be incinerated, either at home or off-site—not unlike throwing out diapers, Hilde noted.

The waste packets can be used in a bio-gas digester, which produces methane gas while killing off pathogens.

The result is a potent fertilizer suitable for edible crops.

Alternative Cost-Benefits

Based on each of these options, traditional toilets do not necessarily have to be replaced. With each of these options, a home would have to keep its septic tank in order to process the “gray water” from the kitchen and laundry.

They suggest studying the costs and benefits of maintaining the current septic treatment at most homes, with the addition of aquaculture and the widening of coastal inlets.

Jobs, food, and fertilizers could be created from this endeavor, whereby not only the oysters, but also the wastes and the macro-algae that grows around them could be harvested as fertilizer.

“Why don’t we try it  and see how much [nitrogen] is removed by reducing our inputs, then we can go to the next step?” asked Earle.

An Ecological Treatment System

This schematic by Ron Zweig proposes a centralized treatment system based on John Todd's ecological design principles

Another option is to install a centralized treatment plant with ecological principles in mind.

In this design, wastewater is treated with a biogas digester that releases methane, which can be used as energy to run the system– or cook food or heat a home.

The primary-treated water is then filtered through aquatic plants and wetlands, where the nitrates decompose and are consumed by beneficial bacteria. These aquatic plants may be composted, and the treated water can be reused to irrigate trees and non-edible plants.

Recognizing that not all residents would be comfortable installing an alternative toilet in their homes, Hilde noted that it will take serious study, modeling, and public outreach for people to understand that the systems are safe and just as effective as traditional toilets.

“We assume that we’re incapable of handling our own waste. That’s a really bad assumption,” she said.

While we have to take the issue of nitrogen (and other nutrient) pollution seriously, we also need to examine the unintended consequences of sewering the entire coast. What impact will pumping and discharging millions of gallons of water have on the aquifer, not to mention, on CO2 levels in the atmosphere? What are some ways we as residents can reduce our nitrogen output on an individual scale?

Last week, I went to an interesting talk by USGS hydrologist Denis LeBlanc, who described the role of the Sagamore Lens in supplying the Upper Cape’s fresh water.

I’d been skeptical that pumping wastewater all over town to a centralized location for treatment, and possibly discharging it through an outfall pipe off of Nobska Point, would not impact our groundwater levels. But according to Mr. LeBlanc, even at a rate of 3-5 million gallons a day, that kind of discharge is peanuts, compared to the volume of the resource.

Whether or not an outfall pipe is a good idea is still up for debate. Experts, including Mark Rasmussen of the Coalition for Buzzards Bay, say that the strong currents at Nobska would create enough “flushing” to dilute the wastewater (treated to tertiary standards) so that it would not impact marine life or public health. But still– in a world where water is considered to be “blue gold,” is it responsible to discharge it into the ocean? Even if we can’t drink it, couldn’t we reuse it?

Eco-logical design

At a conference at WBNERR last spring, environmental designers presented some very intriguing ideas on how to turn wastewater into a resource.

These weren’t pie-in-the-sky dreamers, or con artists trying to sell you back your own pee as drinking water. These were businessmen who had built their reputation on some common-sense notions: why should you flush your toilet or water your lawn with drinking water? Why should we still be using the 2,000 year-old Roman aquaduct system to sewer our communities?

To the speakers, the saying, “the solution to pollution is dilution” is simply not the case. Instead, they suggested a closed-loop system, in which gray water is continually re-used within a building, with minimal loss.

Patrick Lucey, president of Aqua-Tex, a water management consultancy firm in British Columbia, showed slides of a LEED-certified complex he designed on a working waterfront section of Victoria.

The system is designed to reuse the gray water from sinks and showers and collect rainwater from the roof. The “wastewater” is then treated in a centralized sewage treatment that one might mistake for a luscious garden.

Wastewater from toilets is treated to a standard that could be safely used for doing laundry or watering non-edible plants, Mr. Lucey said.

The system could go several steps further by including a bio-refinery to utilize solid waste and garbage as bio-fuels for heating; co-generation technology to create electricity; and removing nitrogen and phosphorus from effluent for use as fertilizer.

Engineered ecology

Closer to home, projects at the Wrentham Mall and Gilette Stadium in Foxboro (home of the Patriots) have achieved 75-95 % water reuse by employing ecological design principles. If every large public building could do that, we’d go a long way in reducing the 1,200 gallons that Americans consume on average per day (through showers, toilets, laundry, dishwashers, and food production).

Even closer to home, a Woods Hole-based firm, Todd Ecological Design, has set the standard for using nature’s principles to deal with wastewater. In municipalities, golf courses, factories, and campuses worldwide, the EcoMachines designed by Dr. John Todd, one the founders of New Alchemy Institute, use micr0-bacteria, plants, and invertebrates to effectively digest the harmful components of wastewater. Designs often include tropical greenhouse gardens that help make this process possible, even in cold climates.

However, as Falmouth’s wastewater superintendent pointed out after meeting with Jon Todd (Dr. Todd’s son), the EcoMachine cannot get the nitrogen content low enough to meet the limits set by DEP.  In order to prevent further estuarine degradation, some parts of Falmouth need to reduce nitrogen to 3 milligrams per liter– the equivalent of 1.5 drops in a bathtub– which will likely require the services of a modern wastewater treatment plant.

You are what you eat

But there are still possibilities for concerned residents to reduce their nitrogen output. Eating less meat is one idea proposed by Dr. Eric Davidson of the Woods Hole Research Center. While this might be a startling idea to some, consider the fact that the amino acids in animal protein are made up of nitrogen, and to a large extent, are passed out of the body.

If we’re eating meat three times a day, we have a bigger nitrogen footprint. For those who don’t want to be vegetarian, thinking about portion sizes, or whether they’re eating beef, or less nitrogen-demanding pork, chicken, or fish, makes a difference.

-Eric Davidson, sr. scientist, Woods Hole Research Center

Another reason to cut down meat consumption takes a global view: in places like Brazil, rainforest is being cleared at alarming rates in order to create cattle pasture. Cutting forests reduces the earth’s ability to process CO2, and also releases extra greenhouse gases (like NO2) into the atmosphere. So, if not just for the local environment, eating meat (or chosing not to) from these places can make a big difference in terms of climate change.

What else can you do?

Finally, debate over sewering sometimes leaves out small, yet significant components of our community’s total nitrogen output: stormwater and fertilizers. If we could eliminate chemical-based fertilizers from our lawns and gardens, Falmouth could reduce nitrogen in estuaries by at least 10 %. (For info on how to reduce your lawn’s N-footprint, see the Falmouth Friendly Lawns brochure.)

And if the town could install more catch basins to deal with stormwater, less nitrogen (and other pollutants) would flow directly from the roads to sensitive ecosystems. One fun fact to remember as you’re driving in a rainstorm: that first flush of rainwater from the road brings NOx emissions from your tailpipe directly to the nearest water source.

So, a few nuances to consider as we head down the road to figuring out how to create a wastewater design to meet demands of the next century. And we didn’t even get into I/A systems, such as Nitrex or RUCK.

Special thanks to David Dow for putting his two cents in on these issues. As always, we welcome comments, questions, and perspectives.