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Finnish project to heat homes using wastewater treatment process

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Lahti Aqua and Lahti Energia in Finland have signed an agreement to utilise heat contained in treated wastewater in district heating.

Heat will be recovered at a heat pump to be built in connection with the Ali-Juhakkala wastewater treatment plant. The facility will be built by Lahti Energia, which will also be responsible for the plant’s operations once it is completed.

The Ali-Juhakkala plant is Lahti Energia’s first district heat pump investment. It opens the doors to centralised, intelligent heat recovery.

The plant will recover 16.9 GWh of heat annually. This is equivalent to the annual energy demand of 1,000 detached houses. The joint project will reduce CO2 emissions by 1,700 tonnes per year, which corresponds to the emissions from driving an average car 11 million kilometres.

“A heat pump plant is an investment in energy efficiency and a circular economy,” said Jouni Haikarainen, CEO of Lahti Energia. “The project will reduce the use of fossil fuels in district heating production and increase the amount of non-combustion district heating in Lahti.”

Jouni Lillman, Lahti Aqua’s CEO, commented: “In wastewater treatment plants, the biological treatment process requires a certain temperature to operate. Heat recovery from treated wastewater after the treatment process is the only correct and most cost-effective place to utilise heat.”

The project has received investment support from the Ministry of the Environment. The plant will be completed in autumn 2022.