Innovative - Low energy consumption - Safe

Thermal Drying


INNODRY® 2E Specific Technology

INNODRY® 2E uses two stages for drying, taking the first from indirect drying (thin film evaporator) and the second from direct drying technology (belt dryer).

Moulding of sludge into granules is achieved after the first stage, with the extruder, with the sludge in the plastic phase, thus avoiding any dust creation.


With the integrated heat recovery system, vapor heat is recovered in the first stage and reused in the second stage decreasing the energy consumption.

The end product is dried sludge in granular form, with a dryness level of 65% to 90% depending on customers’ requirements.

INNODRY® 2E produces a granulate with a bulk density as high as 600 kg/m3 , which is hygienic, biologically stable, dust-free and can be stored indefinitely. The size of the granules can be adapted to suit the final use.

Stage 1: Thin Film Evaporator

The Thin Film Evaporator (TFE) consists of a cylinder, against whose inner wall sludge is spread, forming a thin layer under the effect of the central rotor‘s peripheral speed.

The blades, located on the central rotor, spread out and push the sludge from the inlet to the outlet of the TFE. The TFE‘s walls are heated either by thermal oil or steam. Sludge dryness after the TFE is around 45%.

The vapour extracted from the TFE is used to heat the air of the belt dryer, within the Integrated Heat Recovery System.

Sludge Extrusion

At the TFE exit, the sludge, in a plastic phase and malleable, falls directly into the extruder.

It is pressed through a perforated grid, enabling the formation of sludge strings, whose length fluctuates according to the sludge‘s fiber content. The extruder is regularly cleaned by a scrapping system and is also equipped with a fully-automatic screen exchange system, which ensures very low maintenance.

Stage 2 : Belt Dryer

The granules formed in the extruder are deposited in the belt dryer via a swivelling conveyor that distributes the granules evenly across the whole belt width. The belt’s progress is regulated to ensure that the granules are not exposed to any movement that could cause them to rub against each other, preventing dust creation.

The belt speed can be adjusted in order to match the requested dryness. The sludge is maintained at a temperature around 80°C in the belt dryer, before being cooled down to a final temperature of 35°C.

The belt dryer is dimensioned to suit the dry solids level required at its outlet (65 to 90%).

Odour emissions are avoided by operating the belt dryer at a slightly negative pressure.


Integrated Heat Recovery System

The two stage patented INNODRY® 2E design is unique as it allows the vapour extracted from the thin film evaporator to be used to heat the hot air of the second stage. This feature helps reduce the heat required to dry the sludge.

Thanks to the patented integrated heat recovery system, INNODRY® 2E needs less than 700 kWh/t (1’080 BTU/lb) water evaporated to dry sludge, which is recognized as the lowest energy requirement for a drying system. This represents an energy saving of 30 to 40%.


Sludge is transformed into granules in the extruder, while the sludge is in a plastic phase. Then, the granules are deposited onto the belt dryer without any friction.

Containing risks works, avoiding risks works better

By avoiding the production of dust and the use of high temperatures, especially with the dry granulate, the INNODRY® 2E also avoids explosion risks and reduces the risks of combustion to such a level that it is fully compliant with the European Explosive Atmosphere (ATEX) directives without any oxygen monitoring or control. This is unique to the INNODRY® 2E.



Combined Dryer
with Integrated Heat Recovery System



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