From ancient times to modern-day, some places manage water and excreta in a smart way. Recently, I visited one — the Biocycle Farm in Eugene, Oregon.

Flush the toilet in this town, and here’s a surprise: your contribution may be transformed into an eco-friendly building material — poplar trees. This climate-friendly practice recycles nutrients, keeps local rivers clean and could one day spark a new economy.

At first glance, the bathrooms in Eugene and Springfield, Oregon, appear the same as in any other American town. The difference comes after the flush. Sewer pipes connect toilets to the wastewater treatment plant. It’s run by the Metropolitan Wastewater Management Commission (MWMC), a partnership between these neighboring cities and Lane county.

At the plant, the solids (mainly poop and toilet paper) separate from the liquids (dirty water) and both are cleaned. These solids enter a giant tank, like a mechanical stomach, where they’re digested by bacteria. At night, powerful pumps swoosh the processed slurry a few miles down the road to another facility for further treatment.

Over the next few years, this facility converts the partially processed poop into biosolids — human-derived compost.

From the toilets to the trees

Elegant poplar trees line the biosolids facility property, like tall sentinels, separating it from train tracks and an RV lot.

Each day, 200,000 gallons of nutrient-packed slurry flows into the plant. The sludge comes in runny, like a melted charcoal milkshake, but it ends up as moist and crumbly compost.

The first stage of treatment happens in lagoons. The six-acre lakes waft an anaerobic, creek-bottom smell into the air. Here, millions of gallons of slurry decompose for several years. Once the process is complete, a dredge crawls across the lagoon, sucking up the bottom layer.

The dredged goop is thickened with a polymer then squeezed-dry in a machine. The resulting biosolids are piled in long rows, waiting for the summer to be sun-dried.

Much of the biosolids will fertilizer fields of grass-seeds. And about a third of the material grows poplar trees, at the Biocycle Farm.

Biosolids: Trash or treasure?

Back when people dumped used car oil on the ground after an oil change, wastewater treatment plants dumped semi-treated poop anywhere convenient. Now, this sludgy material is regulated to prevent it from polluting. Still, many view it as a waste product.

Millions of tons of biosolids are dumped into landfills across the US, where they release methane, a potent greenhouse gas. Other places burn biosolids, which uses lots of fossil fuels to power the process.

Todd Miller and MWMC have a better idea.

“They’re really valuable nutrients [in biosolids] and we shouldn’t be throwing these things away,” he says. Miller is the Environmental Services Supervisor at the wastewater agency.

Poplars are unique and well-suited for a biosolids farm. “They absorb tremendous amounts of nutrients,” says Miller, “and they’ll take as much water as you throw at them.” These trees are irrigated with recycled water from the treatment plant.

This variety of poplar grows like a racehorse — up to 15 feet per year. Not strong enough for structural timber, it can replace other wood products, such as pulp, wood chips, plywood, or decorative boards like window frames.

Miller dreams of creating a local economy built around these trees. It's a work-in-progress, as he looks for stable relationships with local mills and woodworkers. For the next harvest, he’d like to partner with an affordable housing developer. Then, the wood could benefit housing needs of the community.

Heart of the community at City Hall

In the dappled light, under the canopy of poplars, you're surrounded by tiny bits of everyone in town. The nutrients that passed through each person are here, growing something new. A bit of magic. If someone sought the heart of the community, could this be it? A living, respiring reminder of how we are all connected.

Across town from the poplar farm, the finished product is on public display. The wood decorates the City Council Chambers at Springfield City Hall. Thin, horizontal boards cover the back wall. The wood is pale yellow, specked with rusty-colored knots. It shines a natural beauty among the room’s routine decor.

Here, the local government supports turning waste into something useful. This wood has come full circle.

 

Notes:

• Barry Mays and Cory Boswell. Crop Manual for Hybrid Poplar at the Metropolitan Wastewater Management Commission Biocycle Farm. Jan. 16, 2008.
• Website. About the Biocycle Poplar Farm
• T. Miller. Personal communication. May, 2024.

On a chilly day in February, Pat Lando gave me a tour of an amazing building — the PAE Living Building in Portland. Lando is the executive director of Recode and the co-founder of Nutrient Recovery Services where he works on building-scale nutrient and water recycling systems. In the PAE building, different systems recycle water and nutrients, produce all the energy used in the building and catch water from the sky.

From the outside, the PAE Living Building in Portland, Oregon, is nondescript. Its gray colors and rectangular shape blend into the historic district. But this five story, office building gets the gold for recycling. Rainwater, greywater and even urine, are all reused. And it’s the first building in the world to create carbon-neutral fertilizers from our body’s waste.

Toilets, compost chamber and tanks

The nutrient recycling system begins in the bathrooms. There, ultra low flow vacuum-style toilets quietly whisk excreta down the drain and into compost chambers. In the mechanical room, 20 different composting toilet chambers decompose all the pee, poop and toilet paper from the building.

Urinals are piped separately into a 1,500 gallon tank that’s buried near the composters.

Here’s where the water’s cleaned

All the recycling action happens in the mechanical room. Inside, it’s warm and jam packed with pipes, valves, tanks, switches and controllers. Carefully organized chaos.

The first area of the room treats rainwater. Piped from the roof, it’s filtered into drinking water and supplies the whole building.

Next, is the greywater area. Here, dirty water from showers and sinks is cleaned for reuse. This system uses a giant filter, bigger than an elephant, called an Advantex trickle media filter, made by Orenco. After cleaning, the water is reused to flush toilets and urinals, and for irrigation.

Mining for liquid gold

The urine system is sandwiched between the giant greywater filter and the even bigger composting toilet chambers. Here, Lando and his colleague Pete Muñoz extract nutrients to make fertilizer.

Human urine is rich in nitrogen and phosphorus, the main ingredients in fertilizers. This system extracts these nutrients through distillation. In this process, heat evaporates nitrogen compounds in urine, and separates them from the rest of the liquid.

Here’s how that works: Urine from the below-ground tank is pumped to the top of a tall, 8-inch wide metal tube. It’s called a packed distillation column. The tube is filled with an assortment of small metal pieces that resemble nuts and bolts. This packing material creates lots of surfaces for urine to contact the steam.

Liquid urine flows down the tube, while steam rises from the bottom. When the steam hits the urine, nitrogen, in the form of ammonia evaporates. The vapor is swept out of the tube.

Next, the vapor is condensed back into a liquid. This nitrogen-rich solution flows into a storage tank. The liquid is perfectly clear, purified by the heat and will last for years. It's now fertilizer.

The leftover liquid that reaches the bottom of the distillation chamber is treated again to remove another nutrient —phosphorus. In a machine called a crystallizer, magnesium is added to the liquid. The magnesium reacts with the phosphorus and speeds up a natural process — crystallization. The crystals precipitate, or sink out, of the liquid, making a slurry.

A few times a year, Lando and Muñoz collect the slurry and dry it in an oven. The end product is a white powder called struvite — a slow-release, phosphorus-rich fertilizer.

Products from pee

Plants thrive with pee-powered fertilizers. And these products are good for the planet, too. They take nutrients out of water that otherwise would be a waste product and return them to the land. This offsets the need for fossil-fuel derived fertilizers.   

These liquid gold products are available at a handful of local garden stores. (And stores that don't carry these products yet can ask their distributor to have them delivered.) Find out where at Nutrient Recovery Services's website.

Or, you can make your own fertilizer. Simply collect your urine, dilute it with water (1 part urine, 3 parts water), and fertilize away!

(Your own urine is safe to reuse in your yard without treatment, but if used on veggies eaten raw, wait a few weeks to harvest after fertilizing with urine.)

To learn more about home-scale urine reuse check out the Rich Earth Institute’s resources.

 

“Half the world needs a toilet while the other half needs a better one.”

That’s according to the Bill and Melinda Gate’s Foundation. It’s critical the 3.5 billion people who currently lack safe sanitation options get them. But what’s wrong with the rest of our toilets?  A few things, it turns out:

• Flush toilets hog precious water and flush nutrients down the drain.
• They often pollute the environment and can spread disease. 
• Wastewater treatment plants and the infrastructure needed to maintain them are expensive.
• And there are better options.

Last month, I visited the exhibit, “A Better Way to Go: Toilets and the Future of Sanitation.”  It’s at the Discovery Center in Seattle, curated by the Bill and Melinda Gate’s Foundation. Here’s a peak at what’s inside.

Would you dare drink from a toilet?

This is a drinking fountain, made with a real, but unused toilet. Being so close to a toilet while sipping perfectly clean water may bring up irrational feelings of yuck or eww. I like how this toilet-drinking fountain exposes a gut-level reaction we may not even know is there.

What’s on tap?

I hoped to sample recycled water, called potable reuse — wastewater cleaned to drinking water quality — but there wasn’t any. Tasting options were Seattle city water, carbon-filtered water and bottled water.

But isn’t all this water recycled? 

Earth’s water has been here from the beginning. It’s the same water the dinosaurs drank (and peed out). In the past, public resistance called the “yuck factor” has impeded recycled water projects. But with more droughts and more science showing how safe this water is, attitudes are shifting.

• A recent study surveyed over 2,000 Americans and found nearly half would try it, with another third uncertain.
• Another study showed the potable reuse water was cleaner than both tap water or ground water.
• And it’s a winner in the blind taste tests, too — people preferred it to the tap water.

From poo to plants

These lovely planters thrive with composted poo — called biosolids. It’s compost from a wastewater treatment plant where poop was transformed into nutrient-rich soil. In the past, biosolids were contamination from heavy metals and other harmful chemicals. But now, in places like Washington state, regulations require industries to pre-treat their wastewater, so biosolids are much cleaner. 

This display, created by artist Vaughn Bell, reminds us to put our poo to good use and keep it out of the landfill. In the US, nearly half of biosolids are either dumped into a landfill where they spew methane, or they’re incinerated.

Toilets from other lands

In the real bathroom at the exhibit, you’ll find picture of toilets from around the world; a pit latrine in Durban, South Africa, a latrine inside a hut in Mozambique and one in India, with a door made of hanging fabric. The picture on each stall door is so realistic that the flush toilet inside feels out of place.

Meet the poo doctor

Your poop has a message about your health. These wooden turds are carved into shapes matching what’s called the Bristol Stool Scale. Do you need more fiber in your diet? More water? To find out, match up the shape of your poop to this scale.

Flush with innovation

Over the past decade, the Bill and Melinda Gates Foundation funded a challenge — to reinvent the toilet. Winning toilets must work without hooks-ups to outside power, water or sewer.  They have to kill pathogens, recycling nutrients, look good and be affordable.

Some of the winning toilets were solar-powered, made electricity, charcoal, fuel gas or clean water.

This all sounds amazing, but the complexity of these toilets gives me pause. (And they aren't yet affordable.) Who will maintain such a complex piece of equipment in the places around the world where people need toilets? These spots are often rural or have high rates of poverty.

Doing your business

These companies really have their sh*t together.

Sanergy in Kenya is like an eco porta-potty service. They deliver toilets to those in need, then pick up the full containers.

Poop is composted with black-soldier fly larva. These voracious grubs transform poop into fertilizer and animal feed for local farmers.

In India, Loo Cafes offer free high-tech public toilets. An attached cafe funds the upkeep costs.

Visit the exhibit in Seattle

This exhibit is free and open Wednesday to Saturday from 10 a.m. to 5 p.m. Confirm hours and details here.

The ancient Egyptians were technology superstars. Their towering pyramids, mummified dead, and exquisite art still impress. Another earthly treasure they left behind is more practical — it’s their toilets. These urban, waterless toilets kept poop out of the nearby river. Did they also protect people from diseases that plagued other cities?  

The earliest Egyptian toilets were discovered in ancient tombs, from nearly 5,000 years ago. These portable toilets were similar to ones used today for hunting or camping trips. But that’s not the only place toilets were found.

The pharaoh’s other throne

Archeologists have unearthed toilets from houses and palaces alike. About 3,000 years ago, the Pharaoh Akhenatan and his wife Nefertiti lived in a city now called Amarna. Their palace boasted an indoor bathroom — a shower stall and nearby toilet.

There was no running water, though: not even for the pharaoh. Shower water was hand-poured over the bather. It drained into a basin, also emptied by hand and perhaps taken to a tree growing in the courtyard.

 

The toilet was built into a small bathroom, often next to the shower area. A wealthy person, like the pharaoh, could have used a deluxe limestone toilet seat. The budget version was wooden. The toilet seat sat above a container, partially filled with sand. Pee and poo would drop into it and be covered up with a scoop of sand. This soaked up liquids and prevented odors. When the container filled, someone would empty it — maybe into a trash pit or buried in the sandy landscape away from the house.

Toilets for the people

But not all excavated houses turned up toilets. Why? Some think toilets were only for the elite, that average people went outside to do their business. But not everyone agrees with this idea.

Heidi Köpp-Junk is an Egyptologist at the University of Göttingen in Germany. Some houses were small, she says, so it would make sense for them to put their toilet outside in the courtyard. She imagines it enclosed with fabric, like a tent. Whether this existed or not, none have been found, and it's unlikely they would have lasted: wood and fabric decompose outdoors.

Egyptologist Barry Kemp also thinks personal toilets were commonplace. He excavated what’s called the Workmans’ Village in Amarna. This is where workers, who built the tombs for the city’s elite, lived. Kemp says that the walled village was dense, with narrow streets. Villagers probably used indoor toilets and later emptied their containers.

 

What parasites can tell us

Sand was plentiful and convenient for the ancient Egyptians. Their simple system created no wastewater, which helped keep the nearby Nile river clean, where people fished and harvested plants.

Did this keep the people healthier, too?

Piers Mitchell is a scientist who studies ancient parasites. When he analyzed parasites from ancient Egyptian mummies, the types he found were not connected to poor sanitation. For example, he didn't find whipworm or roundworm, common in adjacent cities in the Near East and Europe, he writes.

Piers thinks the absence of fecal-transmitted parasites was because the ancient Egyptians didn't need to use fertilizer. Each year, the Nile river flooded, leaving rich silt on the banks where people farmed. Other cultures used fertilizers, often from feces, which can spread parasites if not properly composted.

I think their dry toilets helped. Keeping poop out of the water and away from human contact is one way to prevent fecal-transmitted diseases.

If I could time travel, I’d head to ancient Egypt. I’d marvel at their art and architecture, eat bread and listen to the musical lute. Most of all, I’d investigate how they managed their poop: Did each household do it themselves? Or was there an organized system, with a cart pulled by donkey that came for pickup? What ever happened is another secret in the sand, waiting to be discovered.

Notes:

• Kemp, Barry. 2012. The City of Akhenaten and Nefertiti: Amarna and its People. London. Thames and Hudson.
• Mitchell, Piers. 2024. Parasites in ancient Egypt and Nubia: Malaria, schistosomiasis and the pharaohs. Advances in Parasitology. Volume 123. Pages 23-49.
• H. Köpp-Junk, Personal communication. Nov. 2022.
• B. Kemp. Personal communication. Nov. 2022.