Vegetation contribution on phosphorus removal in constructed wetlands

Abstract

Constructed wetlands have been proven as efficient natural-like technologies to treat different wastewater types. However, phosphorus (P) removal with these systems is still a challenge due to their low performance. This study aims to compare, in microcosm subsurface flow constructed wetland system, the PO4-P apparent balance of five macrophytes (Carex elata All., Juncus effusus L., Phalaris arundinacea L. var. picta, Phragmites australis (Cav.) Trin., and Typha latifolia L.) and an unvegetated control to evaluate plants' contribution in P removal. Compared with unvegetated systems, plant presence increased the PO4-P removal between 5.4% (P. arundinacea) and 9.4% (C. elata). Only T. latifolia was able to remove more than the PO4-P load (13.05 g m−2) whereas the removal reached 86.2%, 48.1%, 37.6% and 36.0% for P. aundinacea, C. elata, J. effusus and P. australis, respectively. Considering the total P load (51 g m−2), its removal from wastewater reached the highest value with T. latifolia (21.8% of inlet quantity) whereas the other species had an average removal value of 6.5%. The biennial study indicates: 1) T. latifolia as the best solution to remove PO4-P from the wastewater being able to remove more than PO4-P load (1.5 times); 2) P. aundinacea as other possible choice able to remove about 86% of PO4-P load.