The first full-scale contact filtration plant for advanced phosphorus removal in Switzerland was built 1979. In a twelve month investigation, the following design and operational aspects were considered: optimal chemical conditions for phosphorus removal, multimedia filter configuration, long-term performance of the total process combination (which included conventional treatment with simultaneous precipitation and contact filtration), and operating variables as filtration velocity, filter run time and backwash water use. Under optimal conditions, contact filtration provided consistently low phosphorus and suspended solids levels at reasonable cost.