• Under the effect of solar radiation and the action of an automated windrow turner (Soliamix), water evaporates from the sludge for subsequent removal from the greenhouse by a powerful air draft.
• The fermentation step is promoted by regular turning of the sludge windrows ; the energy released by the oxidation of organic matter in the sludge accelerates the evaporation process.

A unique windrow turning system

Once unloaded in the greenhouse, the dewatered sludge is piled in the form of windrows with the automated Soliamix system. In order to renew the exchange surface and for aeration, the windrows are turned at regular intervals.

The Soliamix range of windrow turners is available in 3 sizes and their operation may be automated.

• Triangular windrow shaping offers a larger exchange surface area than sludge drying beds for the same amount of greenhouse space, resulting in a faster drying process.
• Furthermore, a higher quantity of sludge can be stored.

Perfectly sanitised end-product

The exothermal reactions occurring during the fermentation process generate a high temperature increase (50 to 60°C), thereby promoting sludge sanitisation in parallel with drying.

The dried sludge quality will fully comply with the requirements of the future European Directive on agricultural land application of sewerage sludge.

• Greenhouse drying: a cost-efficient and environmentally friendly option.
• Improve sludge appearance, facilitate handling and storage operations ;
• Reduce the amount of sludge, limit transportation and treatment costs ;
• Open the way to multi-outlet disposal options, such as agricultural land application or energy recovery and hence adopt a sustainable development approach.

1. Solar radiation
2. Radiation reflected into the atmosphere
3. Radiation transmitted within the greenhouse
4. Infrared radiation transmitted within the greenhouse
5. Infrared radiation transmitted into the atmosphere
6. Heat loss
7. Dry air inlet
8. Moist air outlet
9. Evaporation