Cambi signs a sizeable contract in Sofia, Bulgaria

Asker, 3 October 2022, 15:48 CET

Cambi has signed a sizable contract to supply thermal hydrolysis technology for Sofiyska Voda’s Kubratovo wastewater treatment plant in Sofia, Bulgaria. The contractual partner is a consortium of Glavbolgarstoy AD and GBS Plovdiv AD.

Thermal hydrolysis will improve sludge treatment considerably, ensuring pathogen-free biosolids of high quality for recycling to land and reducing the annual biosolids volume by 50,000 tonnes, saving at least 40% of the handling cost. It also increases biogas production by 30%, producing renewable energy for 10,000 Bulgarian households.

“We are pleased that Sofia Municipality invests in a modern sludge treatment solution, setting an example for the region. The project will bring the municipality of Sofia significant environmental and economic benefits. We look forward to collaborating with the consortium DZZD “SWWTP - Kubratovo” in delivering Cambi’s first thermal hydrolysis project in Bulgaria”, said Eirik Fadnes, Cambi CEO.

Cambi’s contract is part of a larger project wherein Sofia Municipality is refurbishing and expanding the Kubratovo wastewater treatment plant, one of the largest in the Balkan countries. The plant operator is Sofiyska Voda, owned 22.9% by the Municipality of Sofia and 77.1% by Veolia.

The project is financed with EU structural funds and designed to meet increasingly stricter environmental standards and rising inflows until 2050. Thermal hydrolysis enables the plant to adapt cost-effectively to future changes in sludge treatment regulations.

The Kubratovo thermal hydrolysis plant is scheduled for commissioning at the end of 2023.

According to Bulgarian law, the consortium’s contract with Sofia Municipality is subject to a holding period. Changes to the consortium contract may have implications for Cambi’s contract.

For more information, please contact:
Eirik Fadnes, CEO, +47 907 20 014



When announcing new contracts, Cambi describes the contract value using the following classification:






Value in
NOK million

15-50 50-100 100-200 >200


About Cambi

Cambi is a global biogas technology and solutions supplier for wastewater treatment plants and anaerobic digestion facilities. Since 1992, Cambi has retained market leadership through continuous innovation and a robust portfolio of proven and patented technologies. With strong project delivery and customer support capabilities, the company has delivered many well-performing installations in 25 countries on six continents.

Cambi’s thermal hydrolysis process increases renewable energy output, reduces operational costs, and minimises greenhouse gas emissions. It is suitable for all biosolids outlets, including land application and thermal processes such as drying, pyrolysis, and incineration. Thermal hydrolysis is compatible with all sludge and waste treatment regulations and easy to integrate at new and existing anaerobic digestion sites.

Cambi is listed on Euronext Growth Oslo, a multilateral trading facility part of Euronext, the largest stock exchange platform in Europe. Find out more at



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