Bottles containing urine and urine-derived fertilizers

This building gets the gold: Here’s how it converts human urine into an eco-fertilizer

The PAE Living Building

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.

Man standing in front of metal equipment with plastic bottles in the foreground.
Pat Lando shows the urine system. Here, nutrients are extracted from human urine to make fertilizers.

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

View into a room with blue composting toilet chambers
This row of composting chambers is where excreta from the building's toilets is transformed into compost.

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.

Large greywater tank with controller in gray box.
This Orenco greywater filter cleans shower and sink water for reuse to flush toilets and urinals.

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.

Metal chamber
Nitrogen is removed from urine in this distillation chamber.

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.

Plastic bottles of clear liquid.
These are bottles of nitrogen fertilizer from the distillation process.

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.

Plastic bottles of urine fertilizers
These products are made from urine and rainwater.

2 thoughts on “This building gets the gold: Here’s how it converts human urine into an eco-fertilizer

  1. Reply
    Tom Liptan - June 10, 2024

    You mention the treated grey water is used to flush toilets and for irrigation. Is there any issue with water temperature on the plants?

  2. Reply
    Laura - June 10, 2024

    Hi Tom,
    By the time the greywater gets sent to any plants, it is not hot. So, no issue with water temp and plants.

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