Sewage sludge
disposal is an emerging issue due to the presence of PFAS compounds being found
in dried sewage sludge biosolids that have been applied as fertilizer. The
presence of PFAS and other concentrated contaminants is dependent on the
availability of sources of the chemicals. This has led to more restrictions on
the disposal of biosolids. The EPA’s draft risk assessment of PFAS in
biosolids, published in January 2025, echoes those concerns. The assessment
found that concentrations of PFOA and PFOS, two PFAS chemicals, as low as one
part per billion in biosolids used as fertilizer could be harmful to human
health. Several states are considering laws against applying biosolids as
fertilizer. Maine enacted a ban earlier this year, but increased volumes to be
disposed of at landfills have triggered landfill capacity concerns among
operators. This has led to higher biosolids disposal costs for sewage treatment
plants. Costs as much as $200 per wet ton have been reported.
Jacob Wallace of Waste Dive
reports:
“More than half of all sewage sludge, known to utilities
as biosolids, is applied to agricultural land in the U.S. today as a
fertilizer. The rest is landfilled, incinerated or used in composting
processes, according to the U.S. EPA.”
One company, Orbital
Biocarbon, thinks it has a solution. President and co-founder, John Day, notes:
“Utilities right now in the U.S. are already outdated,
and you have significant capital expenditure budgets to replace existing
facilities. With regulation coming down the pipe and capacity for disposal
shrinking, our business model provides a huge alleviation to that problem.”
Orbital utilizes a technology
provided by the German company PYREG. The result of the treatment process via
pyrolysis, heating without oxygen, eliminates PFAS chemicals in the resulting
biochar, which is the output of the process. Biochar is a form of concentrated
and bioavailable carbon that can assist plant growth and soil health. The
resulting gas is combusted via thermal oxidation. I wrote previously about
thermal oxidation here. They are currently developing a pilot
project near Pittsburgh that can process up to 14,400 wet tons of sludge and
produce 1,700 tons of biochar annually. They hope to build facilities several
times that size due to the modular nature of the technology. They also hope to
develop it as a standard biosolids solution for large regional sewage
authorities. The resulting biochar is expected to be sold for land remediation.
“The company expects to generate nearly three-quarters
of its revenue from sludge tipping fees, another quarter from biochar sales and
a small percentage from carbon credits created through the generation of the
biochar,” noted Wallace.
“We think we have a good win-win for our business as
well as for utilities,” Day said. “And by destroying those contaminants too,
producing biocarbon and renewable energy, we benefit the environment as well.”
Some facts and info from PYREG's website are shown below.
Orbital Biocarbon recently announced a funding round led by veteran investor and oil
& gas CEO Toby Rice, CEO of EQT, one of the largest natural gas producers
in the U.S. Rice previously bought the landfill gas company Archaea Energy,
which was later sold to BP and is developing some large renewable natural gas
(RNG) projects, processing raw landfill biogas to RNG.
“I back operators who take on hard problems and deliver
lower costs with better environmental results,” Rice said in a statement.
“Orbital is turning one of the toughest waste problems in the utility space
into critical infrastructure and essential services.”
The pilot project near
Pittsburgh is expected to be up and running by mid-2027.
Steps in Orbital Biocarbon’s
process are shown below. These include drying, carbonization, biocarbon,
syngas, and thermal energy. The link below shows how the process works:
https://www.orbitalbiocarbon.com/how-it-works/
Drying
We start with wet, dewatered sludge and remove most of the
moisture in a low-temperature dryer. Drier solids = less energy later and a
consistent feed to the next step.
Carbonization
In an oxygen-free PYREG reactor, we apply indirect heat.
That sustained temperature and residence time thermally break down pathogens,
microplastics, PFAS and other contaminants. There’s no flame and no
combustion—just controlled thermal decomposition that creates two outputs:
biocarbon and syngas.
Biocarbon
A durable, porous carbon that locks away CO₂ and goes to
work. Its high-surface-area and porosity hold water and nutrients, grab
metals/organics and improve soil structure—or get packed into engineered media
for filtration and remediation. Produced pathogen-free under high-temperature
conditions.
Syngas
The hydrogen-rich syngas is cleaned and fully oxidized in a
high-temperature flameless oxidizer. Inside, the 3 T’s—time, temperature, and
turbulence—drive complete destruction of PFAS and related fluorinated compounds
in the off-gas, so no detectable PFAS is emitted. The result: clean, reliable
thermal energy.
Thermal Energy
That thermal energy is recycled back to the PYREG reactor
and the dryer, drastically reducing the need for auxiliary fuel after startup
and keeping operating costs and emissions low.
The PYREG pyrolysis reactors
are deployed in 60+ projects globally, with a few in the U.S. The process is
cleaner than incineration and produces a valuable byproduct.
References:
Orbital
Biocarbon secures key investment to grow biosolids solution. Jacob Wallace.
Waste Dive. December 10, 2025. Orbital Biocarbon secures key
investment to grow biosolids solution | Waste Dive
Premium
Carbonization Technology for a Valuable Business Proposition. Pyreg.
Our Technology - PYREG GmbH
Orbital
Biocarbon. Website. Home - Orbital
Biocarbon
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