Organisms are killed by lime (pH increase) (with CaO in addition to temp. increase).
When added to dehydrated sludge the lime/sedimentation sludge mixture heats up with sufficient heat insulation to 55-70°C – the sludge is epidemiologically acceptable after 24 h.
Slaked lime (approx. 0.2 kg/kg DS) is added to liquid sludge – it is also used for decontamination and for conditioning before dehydration. In order to decontaminate sufficiently, the starting pH must be 12-13 and the storage time at least 3 months.
After sludge treatment, sedimentation sludge can be used in agriculture, composting and biogas production (digestion) or it is disposed of by incineration. Disposal in landfill is possible only to a very limited extent owing to the too high fuel value and the content of organic matter according to the Landfill Ordinance of 2004.