Organic waste

OurCarbon

OurCarbon, a material produced by San Francisco based company: Bioforcetech.

The material is made of sewage sludge, known as biosolids, that has been transformed into a valuable carbon-based pigment and material additive. This process starts by diverting organic material destined for landfill like food waste and biosolids from their unsustainable end-of-life. Had they gone to landfill, these organics would break down and form methane, a powerful greenhouse gas contributing to climate change.

Once diverted, the organics are directed to Bioforcetech’s technology where they are dried with help from thermophilic bacteria and put through a process where they are heated in the absence of oxygen, called pyrolysis. Working together, these two technologies generate the energy required to run them, making the whole process energy neutral. Now transformed into OurCarbon, the carbon molecules in the organics are bonded together, preventing them from breaking down and emitting for thousands of years.

The locked carbon material is utilised as a pigment to colour paints, 3D print filament, wood stains, and even as a screen printing ink. Recently, OurCarbon has been added to a new 80% bio-based screen printing ink by Virus Inks that are already commercially available. Another new fashion application for OurCarbon is a beautiful grey textile dye, and when added to glass in a kiln the material leaves behind a coral-coloured iron oxide pigment. As a material additive, OurCarbon is featured in bio-based resins, concrete and even porcelain.

Each of these applications are not just beautiful, they replace carbon-intensive equivalents like carbon black pigment, mined and shipped concrete aggregates, harmful azo dyes used by the fashion industry or synthetic fertilisers. For every ton of OurCarbon produced from biosolids that have been diverted from landfill, they prevent 10 tons of CO2e from entering our atmosphere (that's about the same as taking two cars off the road for an entire year). With each of Bioforcetech's installations producing over a ton of OurCarbon a day, this new supply chain has the potential to make a big impact.

Making process

OurCarbon is transformed from biosolids into biochar in two steps, both of which leverage the energy within the biosolids themselves. Because biosolids are a wet material, they must first be dried which can take a lot of energy. Normally this is done in a belt, drum, or paddle dryer that burns external fuel to create heat that dries the biosolids as small amounts of the material move through the machine continuously. Water is not easy to evaporate, making this a really big energy load on waste treatment plants.

Bioforcetech's BioDryer takes a much more sustainable approach. Rather than using external energy like fossil fuels, we leverage bacteria to create heat. The BioDryer passes warm air through a batch of biosolids to cultivate thermophilic bacteria, bacteria that thrive in hot environments. As these bacteria grow and multiply, they release heat energy that evaporates the water around them, drying the biosolids. This works for almost the entire drying process. In the end, when there is not enough water for the bacteria to continue to flourish, we introduce heat energy from the second step of our process to finish the job. The process receives biosolids at only around 20% solids content, known to the biosolids industry as 'cake' for its cake batter or mud consistency. Despite being 80% water, the BioDryer can dry 8 tons of this biosolids 'cake' using little to no external energy per batch.

Now that the biosolids are dry, they can be transformed into OurCarbon. This is where the P-Series Pyrolysis process comes into play. Pyrolysis, the process that transforms organics into biochar, is the heating of an organic material in the complete absence of oxygen. Organics like biosolids are carbon-based, which is why they normally break down and bond to oxygen, creating carbon dioxide which in turn warms the planet. When you heat these organics without oxygen, something completely different happens. Almost all of the carbon cannot bond to anything in the reactor of the P-Series Pyrolysis, causing it to bond to itself in strong carbon bonds. These bonds are what form the black carbon colour in OurCarbon, and they cannot be broken for thousands of years. The other small amount of carbon molecules are left to bond to the hydrogen present in the reactor chamber, forming a burnable gas called 'syngas' that is utilised to power the system. By combusting the syngas right away and sending the heat to circulate around the chamber where biosolids are moving, the machine keeps the process going without having the flame ever actually hit the biosolids. This gives Bioforcetech a lot of control over the quality of the process and the OurCarbon that comes out of the machine.

The specific temperature and residence time that the process uses also destroys 'forever chemicals' like PFAS and PFOA, pharmaceuticals, microplastics, and more, turning a notoriously 'dirty waste' into a valuable asset. The whole system can run on the energy it creates indefinitely, and any excess heat that the P-Series unit produces is sent back to the BioDryers to make them even more efficient. The only output is clean, carbon-fixed OurCarbon.

Text submitted by the maker and edited by the Future Materials Bank. For information about reproducing (a part of) this text, please contact the maker.