Cleaning dirty water more efficiently
Utrecht’s sewage treatment plant (rioolwaterzuiveringsinstallatie, rwzi), which cleans 75 million litres of wastewater each day, is an outdated plant. Components are worn and due for replacement, and it will not be long before the cleaned water will no longer be fulfilling the standards. For that reason Heijmans and GMB are to modernize the plant for the district water board.
De Stichtse Rijnlanden district water board is having the new treatment plant built due to more stringent standards which are to be set in future in terms of the quality of treated water and because the current plant is outdated.
Clean and economical
In due course, the new system will be removing twice as much nitrogen and phosphate, making it at least 30% more economical in terms of energy consumption. Once commissioned, the current system will be decommissioned.
The treatment plant will be running on Nereda technology, with the water being treated by means of bacteria in the form of sludge granules. This will make it easy to separate the sewage sludge and the cleaned water, as the sludge granules will sink to the bottom. Heijmans previously adopted this technique within the compass of a project for the water board.
The new plant is to be built alongside the outdated plant and will be a fair bit smaller. This is due to such factors as the use of the Nereda technology, which renders large secondary sedimentation tanks superfluous, saving a great deal of space.
The project encompasses the design, build and 10-year maintenance of the sewage treatment plant. The DBM (design, build, maintain) contract is worth in excess of € 120 million. Heijmans’ share in the consortium equates to two thirds and that of GMB equates to one third.