Abstract

The objective of this research was to evaluate the fate of aromatic compounds and organic matter in pilot constructed wetlands (CW) treating Pinus radiata and Eucalyptus globulus sawmill industry leachate. Six lab-scale surface flow CW were built and fed in batches. Three CW were fed with P. radiata leachate, while the other three CW were fed with E. globulus leachate. Each group of three CW included two CW planted with Phragmites australis and one unplanted CW as control unit. A stable hydraulic retention time of seven days was maintained in each CW. The organic loading rate was gradually increased in three phases in the CW fed with P. radiata leachate (i.e., from 12 to 19 g COD/m(2)/day) and with E. globulus leachate (i.e., from 14 to 40 g COD/m(2)/day). The operation of the six CWs lasted 98 days. The CW treating P. radiata and E. globulus leachate had a similar performance. The highest performance was obtained by the unplanted CW (approximately 10-20% higher than the planted CW), without significant differences observed between the P. radiata and E. globulus leachate treatment, regarding the removal efficiencies of organic matter and total phenolic compounds. The planted systems were probably affected by the high concentrations of these compounds applied, which probably created a toxic environment hindering the microbial community growth.