Work on the project in Dunbar is finally ready to start in the new year, more than four years after Scottish ministers gave their consent for the scheme.
The board of parent company Pennon has now given the go-ahead to spend the money and said construction would finally start at the Oxwellmains waste treatment site in the first quarter of 2015. Completion is scheduled for December 2017.
Interserve is already building the £154m Glasgow Recycling & Renewable Energy Centre in Polmadie for Viridor and is understood to have been chosen for the Dunbar scheme too.
The new plant will treat 300,000 tonnes per annum of waste.
In a statement, Pennon said: "Following a competitive procurement process, an EPC contract is also already in place with trusted suppliers. The project is therefore 'shovel ready' and construction is expected to commence in Q1 2015."