2. Main treatment routes

These two objectives, qualitative and quantitative, will be achieved through a series of unit operations involving volume reduction, dry matter degradation or stabilization.

• Volume reduction is typically achieved through liquid/solid phase separation operations by decantation, filtration or evaporation, as encountered in thickening, dehydration and thermal drying techniques.

• Degradation of the sludge's organic matter by biological processes (digestion, composting) or thermal processes (incineration at 850°C, wet oxidation of liquid sludge thickened under 45 bar at 250°C) will also lead to a smaller final volume.

• In practical terms, stabilization is achieved by slowing down or even eliminating the putrid biodegradation of the sludge's organic matter, by various biological,...