Urban ecology -the creation of more sustainable cities -was discussed much in Denmark in the late eighties. Most of the initiatives to project were taken by private persons and NGOs. These initiatives were characterised by being:

This project can be seen as a reaction to this. It is a top-down, large scale, integrated project with emphasis on documentation.

The block comprises of 129 apartments with approximately 250 residents. The Pyramid 'green' sewage treatment plant is the most spectacular element in the entire project. The Pyramid is situated in the Hollandervej/Fredensgade block in Kolding. All sewage in the block is collected, pre-treated in a small underground mechanical-biological sewage treatment plant, sterilised in an uv-ozone filter, pumped to the Pyramid, where the sewage are further cleaned by algae and plants. The total surface of the tanks is 840 m2 and the total tank volume is 460 m3. From Pyramid, the sewage is 'polished' in a reed-bed and infiltrated in the ground. In principle, no wastewater leaves the block.

The Pyramid was operational in 1994. The project consists of:

One of the original basic ideas was to use the Pyramid as part of the common space for residents in the block.

Much can be learned from the Pyramid case. The point of view is decisive when the Pyramid is evaluated: is it a project, demonstrating possible 'alternative' technologies, or is it the best solution for the sewage problem in the Hollrendervej/Fredensgade block. It is quite obvious that the project has to be seen as a demonstration project, demonstrating a technology that could be used in other places -places without possibilities of connection with a central sewage treatment plant, for instance remote villages and villages on small islands.

An important lesson learnt is about the conflicts between visions of sustainability and health hazards. The original vision was that the Pyramid could be used of the local residents for growing their own vegetables. Health authorities, however, would only let people with an exam in sewage handling enter the Pyramid. Furthermore, they would not let any kind of human food grow there due to the risk of epidemics (even though the sewage is sterilised before it enters the Pyramid).

A lot has been learnt about how to treat the algae, the plants and the fish. One of the general lessons learnt is that the persons responsible for the Pyramid have to be very well trained and it takes time before they have sufficient experience in running the facility. The rather extensive use of energy suggests that the winter in Denmark is too dark and too cold for a technology based on growing algae and plants. The residents have accepted the project, but it resulted very difficult to engage them fully in this basically top-down driven project.

The Pyramid project has meant a lot of PR for the Municipality of Kolding and the other actors involved in the project. It was used as one of the examples on sustainable urban renewal in the Danish National Report to Habitat II. The final, but perhaps most important lesson learnt, is about transferability. Some kinds of urban infrastructure technologies are rather sensitive to the specific local conditions. Not only the climate, but also the sunlight conditions in wintertime and the soil structure is quite important here.

The environment and the residents of the apartment block.

Department of Buildings and Energy (Engineering), Technical University of Denmark
Denmark
Morten Elle, tel. 0045 45 25 15 42

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case

Urban Policy > Urban environment

Urban renewal