This study evaluates the performance of a mixture of river sand and dolomite (10:1, w/w) used as substrate in vertical-flow
constructed wetlands in removal of phosphates. Two duplicate pilot-scale artificial wetlands (total 4 units) were set up outdoors,
planted with Phragmites australis and fed with a synthetic sewage solution, corresponding to medium strength municipal
wastewater. The wetlands were fed with two batch (intermittent) operational modes and their effluent was monitored for the
presence of soluble phosphates over a period of 3 months. Laboratory (batch) incubation experiments were also carried out
separately to ascertain the phosphate adsorption capacity of the two materials (i.e. sand and dolomite). The wetlands were
capable to remove more than 45% of initially applied phosphates. Phosphorus accumulation in the wetlands body at the end of
the operation period was in the range of 6.5–18%, as compared with the unused media. The Ca Mehlich-III extractable content
was also increased, indicating that the removal of phosphates would be mainly attributed to the sorption of orthophosphate ions
onto calcium carbonates and/or to the precipitation of orthophosphate ions with calcium ions as the respective insoluble calcium
phosphates