Circular sludge treatment
Your most difficult residual stream, solved for good.
MID MIX® converts almost any sludge stream into Neutral: a certified raw material with a negative CO₂ footprint. On your own site or fully taken off your hands, away from the rising costs and regulation around incineration and landfill.
The reality of any industrial process
Sludge treatment is not your core business, until it puts pressure on your operation.
Four developments determine how long that stays true.
Operational continuity
Your sludge has to leave the site, because you have no buffer or treatment capacity of your own. Rates, quotas and certainty of outlet are all under pressure. How do you stay in control?
Costs
Incineration rates and CO₂-fees on waste incineration continuously drive costs up. National waste taxes are steadily closing the exemptions and loopholes that used to keep sludge disposal affordable. Today’s cost level is not a given.
Capacity
Demand for treatment capacity keeps growing, while existing incineration capacity is already scarce and under pressure, and export routes keep narrowing.
Regulation
PFAS, microplastics and other pollutants are under ever increasing scrutiny. At the same time, frameworks such as the EU Waste Framework Directive and National Waste/Circular Economy Programmes push reuse ahead of incineration and landfill.
Not every point here applies to every situation.
Together, though, they’re the signal that the current route isn’t built for the years ahead.
From sludge to product
Sludge cake → MID MIX®-reactor → Neutral
1 · Input
Sludge or similar waste (18–70% d.s.). For example industrial sludge, sewage sludge, digestate, screened sand and more.
2 · MID MIX®-reactor
Quicklime (CaO) reacts with the moisture in the sludge at ~90°C, pH ≥12.5.
3 · Output
Neutral: a white, dry, certified end product. If there is ammonia present, it is converted into ammonium sulphate.
Watch the video to see how that works in our pilot plant:
Pilot plant
Our pilot plant has processed 30+ different waste streams to date, from sludge cake to screening sand. The first full-scale line is in development. Released ammonia is captured at more than 98% and converted into ammonium sulphate.
Validating the proces and end product
The evidence behind it all
1 · LCA-result (Tauw, 2023)
Environmental price of €–30,43/ton for MID MIX, against €+27,92/ton for mono incineration
2 · Certification
SGS Intron has positively assessed Neutral as an active filler in concrete (NEN-EN 12.620) and as a substitute for primary hydrated lime in asphalt (NEN-EN 13.043).
3 · Capacity
8 tonnes/hour per line, scalable to 60,000 tonnes/year at 24/7 operation, and expandable with additional lines. Fast start-up, so shift-based operation is workable too.
4 · Patented worldwide
VSGM holds the exclusive worldwide rights to the MID MIX® technology.
Environmental cost: MID MIX vs. mono incineration of sewage sludge
A negative environmental price means a net environmental benefit.
Tauw (2023). LCA of primary Neutral production under the MID MIX process.
Environmental price in euros per tonne.
How it works
MID MIX uses the natural lime cycle.
MID MIX uses the natural lime cycle. Water from the sludge reacts with quicklime to form calcium hydroxide; organic material and CO₂ from the air react to form calcium carbonate. The reaction generates the heat for the that is controlled at around 90°C, with no external heating. The pH rises to at least 12.5. What remains is Neutral: a white, dry powder of calcium hydroxide and calcium carbonate, with valuable applications. There are no residual waste streams from the process.
Heavy metals are structurally encapsulated, which sharply reduces leaching. Organic contaminants such as PAHs and PFAS typically end up 5–10× lower in Neutral than in the incoming sludge, measured per kilo of dry solids.
Our approach
A step-by-step route
Our process follows logical steps. A project still carries a lot of uncertainty, especially at the start. We take that on one step at a time, building towards a comprehensive final solution.
Phase 1
Feasibility scan
We test your sludge stream and figures against the feasibility of MID MIX. Optionally including a trial on your stream.
Phase 2
FEED-engineering
A full quotation based on FEED-engineering, including all data required for a permit application.
Phase 3
Preparation and construction
Detailed engineering followed by construction and install at your site.
Phase 4
Commissioning and start-up
We fully commission the plant and make sure everything works as agreed.
Phase 5
Operation + support
An operational model that fits what you need, with ongoing support.
typical payback period
Does this fit your sludge stream?
The first step is small. We look at your stream: composition, dry solids, volume, and which outlet route the Neutral would get. If it’s feasible, we work out the details together from there.
And if MID MIX doesn’t fit, we’ll think along on what does.
A circular solution for sludge treatment with a strong business case.
Contact
Certification
SGS Intron
NEN-EN 12.620
NEN-EN 13.043
© 2026 VSGM B.V. · MID MIX® · Neutral