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Researchers see an extreme circular economy: No pooh-poohing!

Imagine that you are eating dinner on a ceramic plate while drinking water from a cup from a plastic bottle, all the while sitting in a brick home. This is a very ordinary situation except that your cup, plate, and even your home were made from recycled feces.

Imagine using your poop as a propellant to launch a spaceship from Mars to protect you from cosmic radiation.

My upcoming book “Flush” will explain how this misunderstood byproduct is an undervalued natural resource.

Poop is a powerful resource: it can be used as medicine, fertilizer and biomethane gas, and even reclaimed water. This is just a small portion of the excremental potential. Its biological, chemical, and physical attributes have inspired more forward-looking brainstorming about other things we can make from our waste.

A hidden asset for space exploration

Particularly, the extreme limitations of space have prompted scientific innovation towards a more circular economy in which nothing is wasted. This invention has been based on a universal truth: everyone has to go at some point, even astronauts. One NASA crowdsourcing challenge focused on the poop was the Waste to Base Materials Challenge: Sustainable Reprocessing in Space. Another asked for new ideas for lunar toilets.

It’s all about self-sufficiency: Steve Sepka (project manager for the Trash Compaction and Processing System at NASA’s Ames Research Center, California) stated that one of their goals is to make polymers out of organic waste for spaceflight propulsion systems.

Sepka explained in an email that the space agency initially considered producing fuel from Mars resources for a return flight. NASA is looking into whether astronauts could benefit from repurposing crew waste.

Scientists have suggested that wastewater density could be a way to protect crew members from

radiation exposure during extended space missions. NASA’s Water Walls Architecture is a multipurpose proposal. It envisions a space capsule with multiple compartments filled with water and sterilized waste that can be used as radiation shielding. Water is the primary ingredient in urine and feces. The tightly packed atoms and molecules of hydrogen and oxygen within the water provide a greater density of cosmic radiation-blocking nuclei than metals. It is a good deflector.

According to Peter Guida (the liaison biologist at NASA’s National Space Radiation Laboratory) and Brookhaven National Laboratory scientist in New York, a water-based shield could be effective in blocking radiation particles.

Every ounce of cargo in space is precious, even water. He said, “If it’s not there anyway, can it be used for something?” It should theoretically work.

A plastic proposal

Try to imagine wastewater treatment plants on Earth being multipurpose resource recovery facilities. Researchers are working to create biodegradable plastics from existing waste streams as an alternative to plastics made of fossil fuels.

It is still difficult to create eco-friendly containers and bottles from the waste we leave behind, according to Zeynep Cetecioglu, associate professor of industrial biotechnology at KTH Royal Institute of Technology, Stockholm. However, the cost of wastewater treatment plants that meet pollution limits could be offset by developing a more efficient and economical method to recover new products from wastewater. She said, “I believe it’s a win-win.”

Anaerobic digestion, which is a microbe-dependent process, is used by many wastewater treatment plants to produce biomethane gas from sewage. This sustainable fuel alternative can be made from wastewater. Cetecioglu Gurol, along with other researchers, discovered that organic compounds produced during the biogas production process are a good source of carbon to create bioplastics. Now, the goal is to increase production efficiency. She said, “We are still in baby steps.”

Some bacteria species can naturally produce a type of bioplastic called polyhydroxybutyrate (or PHB) by eating organic material. PHB, unlike many petroleum-based plastics, biodegrades quickly under normal environmental conditions.

Researchers like Kung-Hui Chu (a professor of environmental and water resources engineering at Texas A&M University) have been drawn to a bacterial strain called Zobellella dinitrificans ZD1. Chu and his colleagues discovered that the strain can thrive on both glycerol (an industrial byproduct), wastewater, and sewer sludge. Because it can accumulate PHB in a wide range of conditions, it is a promising candidate to transform waste into bioplastics and other useful products such as fish food.

Bricks!

The majority of treated sewage solids in the world are still burned or buried. Although the ash produced by incinerating waste is reduced to a fraction, it is still commonly dumped into landfills. Researchers are also looking into how to make the solids and ash useful products.

These recycling methods could produce a lot of bricks. The Royal Melbourne Institute of Technology in Australia has been working to solve the problem of clay soil being excavated for brick production. They have also explored how biosolids can be incorporated into fired bricks. Making poop bricks may seem unusual, but animal dung has been used for centuries to make pottery and homes.

Clay bricks made with clay from Melbourne residents were not as strong when fired at almost 2,000 degrees Fahrenheit for 10 hours. They were nevertheless lighter and more insulating than traditional bricks. Abbas Mohajerani, a civil engineer, and his colleagues at the institute proposed that bricks made from at least 15% biosolids could still be used to meet engineering requirements. They also have the potential to recycle the millions of tons worth of poop leftovers.

Another group of researchers from the Melbourne institute conducted a follow-up study and found that raw biosolids (charcoal made out of biosolids), biochar (charcoal made out of biosolids), and incinerated waste sewage ash could all be used to replace cement. Others in the UK have also suggested that sewage waste ash could be used in tiles and glass ceramics, which has the potential to be used in a wide range of applications in the building sector.

The Museo Della Merda, Italy, has already produced terra cotta tiles and flowerpots from a cow-pie-and-clay mixture. It is called Merdacotta.

The yuck factor may prove to be a greater barrier to repurposed-poop consumer products like ceramic plates and bioplastic cups. Researchers can tap into a wealth of raw materials, which could be used to aid in exploration and increase sanitation infrastructure investments by converting waste streams from revenue. Even better? Even better?

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