Sludge Treatment
- Stabilisation - Aerobic stabilisation of primary and secondary sludges can be carried out in an aeration tank. Because of the high oxygen requirement, this process is energy intensive and costs are high.
- Composting - Composting is an aerobic bacterial decomposition process to stabilise organic wastes and produce humus (compost).
- Anaerobic digestion - Anaerobic digestion is a bacterial decomposition process that stabilises organic wastes and produces a mixture of methane and carbon dioxide gas (biogas). Anaerobic digestion is usually carried out in a specially built digester, where the content is mixed and the digester maintained at 35 oC by combusting the biogas produced. After digestion the sludge is passed to a sedimentation tank where the sludge is thickened. Biogas is collected from the digester. The thickened sludge requires further treatment prior to reuse or disposal .
