Phosphorous removal by the filter materials light-weight aggregates and shellsand – a review of Processes and experimental set-ups for improved design of filter systems for wastewater treatment
Constructed wetlands (CWs) and filterbeds are used throughout the world to treat wastewater. For these systems, selection of a suitable filter material for P sorption is essential, as well as design criteria that enables an efficient treatment. Batch experiments have been the main tool for obtaining maximum P sorption capacities for potential filter materials. They have been run in many different ways something that makes comparisons of the materials difficult. A standard method for batch studies is thus proposed, which should be used in order to
be able to compare and rank the P sorption capacity of different materials used in CWs and filterbeds. Extraction of total P from filter materials from long-term laboratory studies and on-site treatment systems show that long-term experiments mimic the processes taking place in on-site systems. However, these long-term experiments should have inlet P concentration and hydraulic loads similar to the ones used for on-site treatment systems. Changes regarding inlet-outlet configurations, choice of filter material and ways of calculating the volume of the treatment beds are proposed as means for improving the treatment efficiency of these systems.