In the Netherlands the effluent requirements of municipal waste water treatment plants for P will become stricter in 1995. Depending on the design capacity of the waste water treatment plant the effluent requirement will be 1 mg/l P for plants with a treatment capacity of over 100,000 p.e. and 2 mg/l for a lower capacity.
From all the P-removal techniques, such as chemical precipitation, fluid-bed pellet reactor and magnetic separation, the most promising technique in the Netherlands would seem to be biological P-removal with or without a combination of the three other techniques.
In this paper a description is given of biological P-removal, especially the principle, the factors affecting biological P-removal performance, the different modifications and an example of each system in the Netherlands.