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HIGH PHOSPHORUS REMOVAL IN LOW MAINTENANCE FILTER BEDS IN THE NORDIC COUNTRIES
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Paper number 701P0104, . (doi: 10.13031/2013.15814)Authors: Vibeke Rystad, Ole Jacob Sortehaug
Keywords: Filter bed, phosphorus removal, onsite treatment, low maintenance, cold climate, biofilter, constructed wetland, rural areas, treatment performance, pre treatment, reuse of Psaturated filter media, expanded clay, Filtralite
Filter beds for phosphorus removal have been built in Norway since the beginning of the 90's.
Due to excellent performance and low maintenance it is becoming a widespread method for
onsite sewage treatment in the Nordic countries. The system can be built for a single household,
or it can be adapted to suit clusters of houses, schools, kindergartens, small companies etc.
The water runs slowly through a septic tank, then through a down-flow aerobic prefilter followed
by the last step, which is a horizontal filter bed containing a specially manufactured filter media
made of expanded clay.
After the treatment process the clean water is channeled to a stream, river, lake or infiltration to
the ground.
Supported by the Nordic Industrial Fund, a project "Wastewater treatment in filter beds" was
initiated in 2002. The project will end in 2005. Two of the main goals in the project are further
development and optimization of solutions with filter beds in cold climates and development of
common Nordic guidelines for filter beds. Building of two plants in each of the Nordic countries
is included in the project. They will be closely followed up and monitored during the project
period.