Redrock Sewage sludge & biosolids
Rising volumes, tightening land-spreading rules and mounting PFAS concern. Destruction-grade treatment with energy and mineral recovery, not dilution to land.
Supercritical fluid gasification
Treating the waste digestion leaves behind.
Anaerobic digestion and recycling can only take so much. A large share of society’s most problematic waste, from sewage sludge to hazardous by-products and contaminated mixed residues, has nowhere good to go. Supercritical processing changes that.
- Sewage sludge
- Category 1, 2 & 3 ABP
- Refuse-derived fuel
- Plastic-rich rejects
- PFAS-affected streams
The problem
The wastes conventional routes can’t solve.
Digestion needs clean, biodegradable feedstock. It cannot process the persistent, hazardous or non-biological fraction of what society throws away. Recycling, in turn, rejects a growing stream of contaminated, mixed and degraded material.
The old fallbacks are closing. Spreading sludge to land is being restricted, landfill is constrained and taxed, and incineration faces rising cost, carbon and permitting pressure. Meanwhile the volumes keep climbing, and contaminants like PFAS demand destruction, not dilution.
The approach
Water, pushed beyond its limits.
Above its critical point, water is neither liquid nor gas. In that state it becomes a powerful reaction medium that breaks organic matter down to its simplest molecules.
The result is destruction-grade treatment with recovery: pathogens, persistent organics and problem compounds are broken apart, while the energy and mineral content of the waste is captured rather than lost. It is a closed, contained process rather than combustion, which is what lets it handle streams that defeat digestion and recycling alike.
For the technical detail, including where supercritical water gasification does and does not beat incineration, see our reference page on supercritical water gasification of wet waste.
What it treats
The streams we can finally treat.
Category 1, 2 & 3 Animal By-products (ABP)
Animal by-products across all three categories, including the Category 1 material that must be destroyed rather than recycled. A contained destruction route that still recovers value.
Refuse-derived fuel & rejects
The mixed, plastic-rich material that recycling and digestion cannot use, diverted from landfill and incineration.
PFAS-affected streams
Forever chemicals that demand genuine molecular breakdown rather than transfer from one medium to another.
How we deliver
Developed with partners, delivered as systems.
Redrock advances supercritical processing through specialist technology partners and our own in-house development team, so we develop and deliver rather than only advising.
We take a waste stream from characterisation and feasibility through engineering, environmental consenting and commercial structuring to a delivered, operating system, designed for modular deployment alongside water companies, utilities and the waste sector.
What sets our approach apart
Not just another supercritical vendor.
Supercritical treatment is no longer a single-company idea, and we do not pretend otherwise. What separates our approach is where we point it and what we do with the output.
The hardest streams, by design
Others aim supercritical treatment at clean, wet sludge. We build around the streams nobody wants: Category 1, 2 & 3 Animal By-products, PFAS-affected material, refuse-derived fuel and plastic-rich rejects, where destruction is the point.
Recovery that feeds a fuels platform
The gas, the recovered CO₂ and the heat do not stop at the fence. They connect into our wider biomethane and sustainable aviation fuel work, so a problem waste becomes part of an integrated energy output.
Deployed at the source
We design for modular deployment next to the waste, alongside water companies, utilities and the waste sector, rather than concentrating everything in a single distant plant.
Independent and technology-led
We develop our own systems with specialist partners rather than reselling one fixed licence, so the solution is shaped around the waste stream instead of the other way around.
Why now
The old doors are closing.
Land-spreading is closing
Restrictions on spreading sludge and biosolids to land are tightening across our markets, stranding a waste that keeps growing.
PFAS regulation is arriving
Persistent “forever chemicals” increasingly require destruction rather than relocation, a bar conventional treatment struggles to meet.
Landfill and incineration under pressure
Rising gate fees, carbon exposure and permitting difficulty are squeezing the traditional disposal routes.
Resource recovery is expected
Circular-economy policy increasingly asks that energy and nutrients be recovered from waste, not lost.
Have a difficult waste stream?
If digestion, recycling and landfill have run out of answers, let’s talk about what supercritical processing could do with it.
Start a conversation