Both the local situation in the inner Oslofiord and the political decisions of the countries
surrounding the North Sea called for further treatment. Through 1989 and 1990, VEAS
put bits and pieces of known technology together to compose a process for nitrogen
and phosphorus removal to be installed in the area of the existing sedimentation tanks,
only extended in depth. In addition, the process should reduce the amount of sludge
considerably. A working hypothesis was presented in 1990 and later named "The
VEAS Concept" by prof. H. Odegaard, Techn. Univ. of Trondheim. The status for the
development is described in more detail by Sagberg et al. (1995). Figure 1. show the
state of the VEAS Concept by end of 1994. Further adjustments has later been made
and new will be.Introductory tests were run by VEAS with RBC from Klargester, Mechana and Envirex,
with submerged Munthers media, with the Kaldnes moving bed media and with the
upflow BIOFOR system from Degremont. After international pre-qualification, call for
turn key tenders, which were rejected, and finally licence negotiations, the BIOFOR
system was selected for full scale application.