Treatment of rainwater - Life Treasure project

Advanced treatment of rainwater runoff – wet basins in combination with filtration and sorption technology

The EU LIFE-financed demonstration project "Treasure" has established three systems for the demonstration of technologies for advanced treatment of rainwater runoff. The basins are located in Odense, Silkeborg and Aarhus and are described at www.life-treasure.com.

The project is focusing on extending treatment from simple settlement, which is known from wet rainwater basins, to include the dissolved and colloidal matter fractions.

All the systems are based on wet rainwater basins in combination with sand filtration and a sorption technology. As these are trial systems, the basins are provided with various items of equipment for measuring the quality of the rain runoff before and after each of the treatment stages.

Figure 1: Life-treasure systems in Odense, Silkeborg and Aarhus (Photo: www.life-treasure.dk)

The project is being managed by Kenn Lange, Silkeborg Forsyning A/S.

Life-Treasure is an acronym for "Life – Treatment and re-use of urban stormwater runoff by innovative technologies for removal of pollutants." Life refers to the EU programme from which the project has received funding.

Jes Vollertsen, Aalborg University: "High cleaning performance is achieved with the selected combinations of treatment technologies. As the systems are designed as basins resembling lakes and all technical installations are underground, the systems also help to promote natural beauty in the areas. It is necessary to be aware that several treatment technologies are being tested in one and the same basin, and that a final system would therefore be of a slightly different design to the demonstration basins."

The demonstration basins involve significant capital investments. Part of this investment is linked with the intensive monitoring. This will not be necessary with a normal system, and so it will be cheaper there. We implemented a major measurement programme in 2008-2009 in which the effects of the various treatment stages were assessed. The results from this measurement programme can be viewed in newsletters on the project website.

Finance
The project has a total budget of DKK 32,000,000.

Selection of project experiences
Sorption to solid medium filters is the most effective of the technologies tested and, if designed correctly, can reduce the content of heavy metals, for example, to below the water quality requirement for freshwaters. There have generally been problems with the sand filters becoming clogged more quickly and more extensively than anticipated, which led to less water flow than designed. Given experiences with sand filters as outlets from wet rainwater basins, a design with a filtration rate of 0.3 m/dg is recommended.

Contact
Name: Jes Vollertsen
Organisation: Aalborg University
E-mail: jv@bio.aau.dk
Telephone: +45 99 40 84 04

Photos