Phytoremediation of landfill leachate in constructed wetland

The integrated remediation plan of the Laguja landfill, Estonia, includes creation of aconstructed wetland for treatment of landfill leachate. A mesocosm experiment wasconducted in order to estimate the impact of different plant species on purification efficiencyof wetland. The quality of water in mesocosms was monitored during vegetation period. Allplant treatments enhanced reduction of organic matter (BOD: 87-96%, COD: ca 30%, TOC:ca 50%) as well as ammonia and total nitrogen in water compared to unplanted control.Presence of plants enhanced biodegradative bacterial abundance and activity as well asmetabolic diversity of microbial community in water. Water samples from all plant treatmentswere characterized by distinct microbial communities as revealed by molecular fingerprintingtechniques. Most different from the rest of microbial communities were water samples frommesocosm with plants on floating mats. Our results show that in free-water constructedwetlands with vegetation the purification efficiency is not dependent on plant species, whilestructure of water microbial community differs due to plant species.