Each worth £55 million, the two elements may be awarded separately or together. The projects are designed to reduce the impact of discharges to the River Clyde from the waste water works.

One part is the design, construction, delivery and commissioning of the engineering elements of a tertiary chemical dosing plant.

The second part is the design, construction, delivery and commissioning of the engineering elements of a granular activated sludge plant.

Scottish Water said it had split the work into two project races to improve flexibility in delivery but would prefer to award both jobs to a single preferred bidder.

PQQ documentation will be released on Public Contracts Scotland’s tenders website.