A hydroponic plant root mat filter (HPRMF) was compared over 7 months with a horizontal subsurface
flow constructed wetland (HSSF CW) regarding the removal of perchloroethene (PCE) (about 2 mg L1)
from a sulfate- (850 mg L1) and ammonia-rich (50 mg L1) groundwater with a low TOC content. At a
mean area specific inflow PCE load of 56 mg m2 d1, after 4 m from inlet, the mean PCE removal during
summer time reached 97% in the HPRMF and almost 100% in the HSSF CW. Within the first 2 m in the
HSSF CW metabolites like dichloroethenes, vinyl chloride and ethene accumulated, their concentrations
decreased further along the flow path. Moreover, the tidal operation (a 7-d cycle) in the HSSF CW
decreased the accumulation of PCE metabolites within the first 1 m of the bed. The carcinogenic degradation
metabolite vinyl chloride was not detected in the HPRMF. The smaller accumulation of the degradation
metabolites in the HPRMF correlated with its higher redox potential. It can be concluded from this
study that HPRMF appears an interesting alternative for special water treatment tasks and that tidal
operation will show some positive effects on the removal of the accumulated PCE metabolites in HSSF
CW.