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Biological (rapid sand) filters are a widespread environmental biotechnology used at thousands of waterworks in Denmark. These filters should be seen as bioreactors where microbial processes (removal of e.g. ammonia, manganese, ferrous iron, methane, sulfides and natural organic matter (NOM) probably are more important than the simple physical straining processes. Furthermore, new observations indicate a promising potential for degrading organic micropollutants (pesticides, MTBE, gasoline compounds and pharmaceuticals) combined with these processes.

The underlying microbial processes are, however, poorly understood, limiting the management of filters resulting in start up problems and insufficient treatment. The project will improve the biofilters by molecular investigations of the microorganisms responsible for the individual processes in the filters (e.g. nitrification); and by down-scaling the filters to provide insight in the process mechanisms kinetics and effect of environmental factors. Management of the filters (e.g. back flushing, flow rate, carrier type) will be investigated at pilot and full scale, supported by mathematical models. The sustainability and climate friendliness will be evaluated by life cycle assessment (LCA). 

The project is need-driven and strongly focused on one drinking water technology and an array of its applications, and will be conducted by a dedicated, relatively small group in the water sector: one strong university, one of the major industry companies, 4 end-users (the major Danish water suppliers), and a strong international involvement: consisting of a leading university, a knowledge center and a technology supplier.

The project has a total budget of 17.4 mio DKK and is supported by the The Danish Council for Strategic Research ( The project will run for a 4 year period: 2010-2014 and will include 4 Phd's.