Nutrient and Trace Element Uptake By Cattail (Typha latifolia) during in Situ Phytoremediation of Biosolids in an End-of-Life Municipal Lagoon.

The traditional spreading of biosolids on agricultural land is a cost-effective and beneficial option for managing biosolids. However, the increase in land requirements associated with phosphorus- (P-) based rates, tightening regulations, the high costs of transporting biosolids, and the banning of land spreading of biosolids in some jurisdictions call for sustainable alternatives, such as in situ phytoremediation. This study examined nutrient (N and P) and trace element (Zn, Cu, Cr, and Cd) uptake by cattail (Typha latifolia) from biosolids in a wetland constructed in a lagoon cell previously used for primary treatment of municipal wastewater. Six plots (2 m × 2 m) were established in each of eight transects in the wetland. Plant tissues, biosolids and water samples were collected and analyzed for nutrient and trace element concentrations. Cattail dry biomass yields assessed in September during the year of wetland establishment averaged 0.2 kg m^-2. Mean N and P uptake were 5.2 and 0.9 g m^-2, respectively, while trace elements concentrations averaged < 0.001 g m^-2.  In the second season, no significant biomass yield differences were observed between a single cattail harvest (0.61 kg m^-2) and two harvests per season (0.6 kg m^-2). Nitrogen and P accumulations in the aboveground biomass were not significantly affected by harvesting frequency. Results from this study will inform on the effectiveness of wetland phytoremediation for removal of contaminants from biosolids during the decommissioning of end-of-life municipal lagoons.