In connection with the Danish Action Plan on the Aquatic Environment (APAE), the Copenhagen wastewater treatment plants are to be upgraded to nutrient removal. This paper describes the way in which the basis of the decision in respect of design load, choice of treatment process, upgrade type, etc. is achieved.
There are 2 wastewater treatment plants in Copenhagen and it is possible either to upgrade both plants or only to upgrade one and close the other one. It was decided to upgrade both plants and we describe the rationale for this decision.
An extensive effort has been made in order to choose the treatment process. The technical-financial evaluation of various methods will be described, as will the testing of the chosen methods in pilot plants. The design load criteria include the present load, industrial discharges of nutrients, runoff, infiltration, water consumption forecasts, and wastewater temperature.
Finally, the plans for a gradual extension are described. The first stage aims at an extension to the load expected in 1996 when the plant will be put into operation, however, with the possibility to adapt the size of the works during construction, if developments do not correspond to expectations.