The biomass and nutrient and heavy metal content of cattails and reeds in wastewater treatment wetlands for the production of construction material in Estonia

Cattails and reeds are the most common plants in constructed and semi-natural wetlands for wastewater treatment, and can play an important role in both nutrient and heavy metal retention. On the other hand, both plants are highly valued in ecologically oriented construction. The aim of this chapter is to measure common cattail (Typha latifolia) and reed (Phragmites australis) biomass production and the annual assimilation of nutrients (N, P) and heavy metals (Cd, Zn, Cu, Pb) in the phytomass of common cattail (T. latifolia) in two free-water surface flow constructed wetlands (FWSF CWs) and in one semi-natural treatment wetland in Estonia. The phytomass measurements were performed after the vegetation period in autumn and winter from 2002 to 2006. The average aboveground biomass of T. latifolia varied from 0.30 to 1.76 kg dry weight (DW) m−2, and the corresponding values for P. australis were from 0.61 to 1.32 kgDWm−2. Average N, P and heavy metal concentrations showed that the harvesting of aboveground biomass does not have much of an effect on the removal of heavy metals from wetlands.