Turning waste water to energy
A new digester at the wastewater treatment plant in Sofia, increased the biogas production capacity by 25%.
The 7,000 cubic metre tank cost EUR 3.1 million and has been added to the wastewater treatment plant near Kubratovo in the Bulgarian capital.
How it works:
The sludge is stabilized in the digester, it is dewatered and given to farms to fertilize certain crops, the company says, adding that the material is rich in phosphorus and nitrogen. The treated water is discharged into the Iskar River, completing the economic cycle.
The methane from the sewage sludge serves as fuel for a combined heat and power plant that generates 24 GW of electricity annually.
It is operated by Veolia subsidiary Sofiyska voda, producing drinking water for 1.4 million people in Sofia and managing their wastewater.
The company already has four digester tanks built in 1984, and the plant installed in Sophia ranks second among its 2,500 plants in terms of energy efficiency.
More information can be found here