Finally, we got to talk about a topic that concerns us all: human pee! Or if you prefer a more medical term – urine. Aside from urine being an important part of our business, there’s more to why we initiate this conversation over and over again. So, how do we recycle urine?

Although urine is, medically speaking, a liquid waste product of the human body, we’re not really fans of labeling it as waste in any sense.

So, why are we taking this topic seriously?

Social and Environmental Benefits of Urine Recycling 

What is urine?

One man’s trash is another man’s treasure. The same could be applied to urine since it’s our body’s waste liquid product, but thanks to its chemical composition, it can be a real treasure (if you’re a plant).

Are you staying hydrated? You might drink that glass of water now since a healthy person’s urine will contain around 95% of water – the rest being a mix of salts (sodium, potassium, chloride, urea, uric acid). All of us well-hydrated bunch know that the more you drink, the more you need to go. Your urine’s chemical structure is affected by the lifestyle you’re leading. While a healthy person’s pH is around 6.2, drinking alcohol and consuming junk food will cause a minor disbalance. Don’t worry, a range of 5.5 – 7.0. is optimal.

If you’re getting flashbacks from high school chemistry classes, it’s okay. There are plenty of reasons why urine is so interesting, which may also explain why we find it useful.

The main organic component of urine is urea, which is very high in nitrogen, a key ingredient to healthy leafy growth in plants. Your pee contains dissolved phosphorus which plants can absorb immediately, making urine a quick-acting fertilizer.

The city of Amsterdam campaigned in 2014 to raise awareness of the phosphorus shortage. This was done by setting up public urinals and educating the public on repurposing urine as a plant fertilizer. In parts of the world where chemical fertilizers are cost-prohibitive,  recycling nutrients and creating a closed-loop system using this free resource converts waste into treasure.

Urine as fertilizer

We as humans are not very proficient in dealing with the waste our bodies produce. All around the globe, the wastewater is left to enter the earth’s waterways, creating health and environmental problems.

By utilizing urine-diverting systems in composting toilets, we can use urine as a fertilizer and turn it to our advantage. Using diluted urine as a fertilizer in the garden can help us cut water use (say bye to flushing!) while cleaning up the environment downstream (no water-polluting fertilizer runoff).

Recent scientific studies have shed light on the effectiveness and safety of urine.
Stored urine is unlikely to pass the bacterial DNA to other microbes, and its ratio of NPK makes it a safe and effective fertilizer for the crops.

With the invention of sewage systems, western civilization has abandoned all practice of using urine (and feces) as a fertilizer. However, a recent study suggested that “an estimated 330 tonnes of nitrogen and 20 tonnes of phosphorus a day could be retrieved should 10% of the US population collect their urine.” This could have a huge impact on the agricultural industry by providing much-needed natural nutrition for the crops. But why a wider use of urine remains out of sight and out of mind is a topic for another blog post.

Is it safe, though? Absolutely. Otherwise, we wouldn’t be able to pee anywhere outside our homes in fear of a health hazard. However, if you’re reluctant, note that studies conducted suggest that stored and aged urine is as safe as they come. 

Water Filter Systems and the Pee-Pee

The idea behind composting toilets is rationalizing the use of drinking water – which is why they don’t use the flush system. Bearing in mind that your urine has to be diluted (1:10) with water, greywater comes in handy as it’s perfectly suited to be a diluent. 

Urine recycling makes sense only if we truly want to make the best out of it. As previously mentioned, the first step is ensuring that urine is diluted with water. Ever notice those “pee spots” in the park, yellow patches of grass? By diluting urine, we make sure the soil absorbs the best of nutrients from the urine. 

In addition, we suggest you get familiar with the types of wastewater in order to know what is reusable and what’s not. 

Greywaters – the relatively clean wastewater from bathtubs, sinks, washing machines, and other kitchen appliances – may contain traces of dirt, food, grease, hair, and certain household eco-cleaning products. Its degree of cleanliness depends a lot on which type of detergent you use, too.

Greywater with the addition of urine is a perfect example of a waste that can be converted into a resource. The molecules that come from soaps are mainly carbon molecules with phosphate and nitrogen compounds. Nitrogen (N) and phosphorus (P) found in greywater are two elements required by plants, certain bacteria, and fungi to develop.

In order to clean greywater, the solution is to slow it down sufficiently to allow organisms to incorporate N and P before they scatter into the ecosystem. This practice also makes it possible to extract nitrogen and phosphate molecules, often called pollutants, from water to purify water. It’s called Phyto-purification. Integrated into a fast-recycling nutrient cycle, greywater can increase ecosystem productivity. 

1. Greywater shouldn’t be stored (more than 24 hours). Once stored, the nutrients in it will start to break down, creating bad odors.
2. Avoid contact with greywater. Greywater could contain pathogens, so your system shouldn’t be designed to be available for drinking.
3. Find a way to infiltrate greywater into the ground, don’t allow it to pool up or run off. Knowing how well water drains into your soil – the soil percolation rate – will help with proper design.
4. Your system should be as simple as possible. This means avoiding pumps and filters that need upkeep. Simple systems are durable, require less maintenance, less energy, and cost less money.
5. The irrigation needs of your plants should be matched with the amount of greywater they receive

The easiest way to use greywater is the reed bed. Once filtered this way, greywater can also be used to irrigate vegetable plants. For any greywater system, using “plant-friendly” products is essential. This includes those without lots of salt, boron, or chlorine bleach. The build-up of these substances in the soil can damage plants. At the same time, take care of your own health: “natural” body products often contain substances toxic to humans.

Reed Bed

What is a Reed Bed?

A reed bed’s purpose is to mimic a wetland, which simulates a natural filtration system for Grey wastewater treatment, including the urine. 

• A reed bed consists of a watertight area from 1m2 to many hectares with pebbles, small rocks, reeds and other aquatic plants.
• It is an efficient and sustainable source of treatment for contaminated wastewaters.
• Rhizofiltration includes using the plant roots to absorb, concentrate and precipitate heavy metals from water. Some studies suggested that rhizofiltration can remove target metals for mixed contaminants. 

In the reed bed, a food web is created in the root zone of the reeds and plants. The food web hosts microorganisms that degrade any nutrients and organic material present in the water. The reed bed provides important backup capacity should the bioreactor be organically overloaded. Interestingly, some plants do not treat the water directly but rather create the optimal conditions for microorganisms to perform treatment work. Similarly, plants you chose for the reed bed should reflect diversity with some offering shade whilst others attracting insects and birds.

Keep in mind that a reed bed is by no means a “wild” pond which will be used as a mosquito breeding ground, neither will it produce any unpleasant odors. Unlike the pond, the water in a reed bed is not static.  It is a natural-mimicking system including plants, pebbles and rocks, which utilizes power of microorganisms and plant roots in order to deal with the waste in the water.  After going through the filters, it is safe to find its way into the soil, pond, lake, or any other water.

Banana Circle

What is a Banana Circle?

One of the most potent designs of tropical permaculture is the banana circle, also known as a pit garden. This is just a term, though. Note that it doesn’t necessarily need to include bananas if the climate conditions aren’t favorable (although, there are some banana plants that can withstand low temperatures).

• There’s a compost pit where kitchen waste can be thrown.
• The compost then acts as a carbon filter, through which Greywater from the kitchen and shower can flow as it sinks down to the ground beneath.
• Around the compost pit are grasses and leafy plants that love water. The roots keep the walls of the pit in place and provide another layer of filtration.
• When the compost pit is dug, the soil is piled around the rim creating a raised ring. This is where you want banana plants grown. They are voracious feeders (they need a lot of nutrients and water to thrive). The compost pit with its steady supply of kitchen & garden scraps, and greywater filtering down, supplies both in abundance.

Several “Banana Circles” should be arranged sequentially and connected to ensure the organic matter in the pile never comes in contact with the greywater. At the end of the series of «Banana Circles», we find purified water.

Fast Solution 

Since urine is low in pH and ash has a higher pH level, the mix of the two creates a pH-neutral substance. Using just the handful of sifted wood ashes (the chunks can be saved for the compost bin) will boost the potassium level in a bucket of liquid gold very nicely.  Also, wood ashes have an N-P-K ratio of about 0:1:3, plus a lot of calcium. 

Be sure NOT to use wood ashes from treated wood and avoid burning large amounts of glossy paper. Never, ever use coal ashes. Note that hardwoods’ ashes have the most potassium.

If all this is too complicated for you, there’s a simpler, more elegant solution. A system where diluted urine flows through the bottomless bucket with ash, sand, and pebbles should do the trick. It’s not as perfect as a reed bed or banana cycle, but it still helps the proper disposal of urine that won’t be used as a fertilizer.

Urine Recycling: Why Do We Do It?

Rethinking what our bodies naturally produce is crucial for us moving forward with sustainability and eco-conscious living. So the next time you pee in one of our separators, think of all the plants that will enjoy all the NPK you don’t need anymore!