What happens to the sludge produced after wastewater passes through the sewage treatment plant?

Sludge that is produced after the wastewater passes through the sewage treatment plant consists of organic matter and huge quantities of water. At this stage, the sludge is thickened so as to ease the sludge disposal and this is in done by three methods:

1. Incinerating: Sludge is burnt to ashes and used as a construction material
2. Dewatering: Sludge is dewatered and used in the production of fertilizers in combination with other wastes.
3. Solid composting: Sludge is composted to produce gases which can then be used as fuel.