The Bulgarian water plant transforming waste into power and products

From turning on a tap to flushing the toilet, few of us often stop to consider the environmental impact of our water use. The process of providing clean water and treating that water once we’ve used it, however, has a significant carbon footprint. In fact, in many countries, the energy needed to pump and treat our water is thought to add up to around 5% of all greenhouse gas emissions, a figure comparable to the aviation industry.

A few hours after somebody goes to the toilet in Bulgaria’s capital Sofia, what gets flushed away normally ends up at the Kubratovo wastewater treatment plant. Operated by Sofiyska Voda, part of the Veolia group, the plant is one of the most energy-efficient in Europe.

“We collect the wastewater from Sofia citizens. We treat it here so that it's clean when it enters the river. In the process, we produce biogas. This biogas is then transformed into electricity and heat. The heat is used for our processes and the electricity satisfies the needs of this plant,” Stanislav Stanev, the Technical Director at Veolia Bulgaria, told Euronews.

Every year the Kubratovo plant generates around 24,000 megawatt-hours of electricity and heat energy - enough to power 2,300 homes annually. But what sets the plant apart from other water treatment facilities is the efficiency of its digesters where the biogas is made, explains Stanislav.

’’The difference is the amount of biogas produced. Usually, wastewater treatment plants are producing 50 to 60% of their own needs. And here we cover more than 100% of our needs. We are also saving CO2 emissions, approximately 70,000 tonnes per year.’’

In addition to CO2, wastewater treatment produces a lot of gases like methane, a potent greenhouse gas. Capturing and using these gases