Frequently Asked Questions

The HTC process operates continuously with ammonia recovery at ~12–15 bar and 180–220°C, sterilizes the slurry and makes it easily dewaterable.

Downstream, solid/liquid separation is performed (centrifuge or filter press).

Output:
• Liquid: high COD, recirculatable to the digester to increase biogas;
• Solid (hydrochar): hydrophobic and stable.

Data indicates a +10–20% increase in dry matter compared to standards, thanks to improved post-HTC dewaterability.

Results up to ~60% dry matter (vs. ~20% typical) can be achieved when the process is optimized: the order of magnitude is scenario-dependent (sludge type, settings, downstream chain).

The actual sludge reduction consists of the conversion of dry matter into organic acids readily available to be converted into biogas by anaerobic digester bacteria.

No: one of the operational advantages is to proceed immediately with HTC without initial centrifugation; separation occurs after the reactor, on sterilized and more easily dewaterable material, with better yields.

Because transport, treatment, and disposal are paid proportionally to volume. The higher the dry matter content by weight of the sludge and the wetter it is, the more it costs.

HTC reduces the kg of sludge dry matter to be disposed of and increases the hydrophobicity and dewaterability of the sludge.

Furthermore, HTC makes the solid hydrophobic and highly dewaterable, reducing volume and trips.

Yes. HTC can be an alternative to bio-drying/dryers when efficiency is needed, or complementary (initial consultation is performed to model the TCO vs. kWh/€/m³ of water removed). The goal is to win on costs and energy, case by case.

For the end-of-waste status, there are several outlets:
• Packaging/Cardboard: mixtures with recycled fibers, substitution up to 30% of the fibrous material according to technical-regulatory suitability tests; sheets with mechanical properties comparable to testliner 3–4.
• Solid fuel
• Sound-absorbing materials (construction)
• Agronomic use

The output slurry is sterilized (pathogen-free) immediately after leaving the reactor, simplifying management.

The technology acts as a “shield,” reducing PFAS and pathogens. For every project, sampling and laboratory tests are planned to certify performance on your specific sludge.

With HTC, there is no water evaporation but an effective reduction in dry volume due to the transfer of part of the dry matter into the liquid phase in the form of organic acids and the hydrophobic nature of the post-reactor solid. Therefore, for the same “initial % dry matter,” the volume to be managed after HTC can be much lower compared to classic bio-drying.

The standard path:

1. Laboratory & testing on client biomass → technical-economic feasibility study;

2. Sizing

3. Downstream integration: if necessary, option to manage the output solid up to incineration (with attention to phosphorus in the ashes, a critical raw material).

The objective, where possible, is always to avoid landfill/incineration through end-of-waste outlets and material/energy recovery.