Removal of tri-(2-chloroisopropyl) phosphate (TCPP) by three types of constructed wetlands

In this study, three types of constructed wetlands (CWs) (biofilm-attachment-surface-CWs, packed bed-CWs and traditional-CWs) were assembled to comparatively evaluate their ability and mechanism to remove tri-(2-chloroisopropyl) phosphate (TCPP) under continuous flow operation. The removal rate (26%-28%) of TCPP in two types of CWs containing plants was twice as much as that in plant-free CWs in 6-month experiments, and TCPP showed a terminal accumulation phenomenon in Cyperus alternifolius with the order of accumulation of leaf>stem>root. The mass balance indicated that the contributions of filler and hydrophyte absorption to TCPP removal were less than 1%, but the transpiration of hydrophytes may make an important contribution (approximately 10%) to TCPP removal. Species in the genera Massilia, Denitratisoma and SM1A02 may be responsible for TCPP biodegradation. In addition, the effect of TCPP on the metabolic pathways and energy generation in the roots of C. alternifolius suggested that TCPP may be transported and utilized through cellular metabolism.