The methods can be divided into two main categories:
1.Energy recycling:
Energy recycling includes fermentation (biogas production) and incineration. Remaining sewage sludge can be burned in special plants, with the resulting heat being used to generate energy. This method significantly reduces the volume of the sludge and minimizes landfilling.
2. Material recycling:
This includes use as fertilizer to improve the soil. Because sewage sludge accumulates pollutants from the wastewater its quality largely depends on the quality of the wastewater. Therefore, in our opinion, material recycling may be difficult.