Multiple aerobic and anaerobic baffled constructed wetlands for simultaneous nitrogen and organic compounds removal

The objective of this study is to determine the reduction efficiency of chemical oxygen demand (COD) as well as the removal of NH4+-N and NO3--N by the Aerobic-anaerobic Baffled Constructed Wetland Reactor (ABCW). The ABCW reactor was planted with common reed (Phragmite australis), where the hydraulic retention times was set to 1 d and was fed with synthetic wastewater. Supplementary aeration was supplied in designated compartments of the ABCW reactor to control the aerobic and anaerobic zones. The COD reduction efficiency was 98%, while the NO3--N and NH4+-N removal was 36-98%, respectively, which was due to nitrification and denitrification processes. The outstanding performance of the baffled unit was due to the longer pathway as there is the up-flow and down-flow condition sequentially, thus allowing more contact of the wastewater with the rhizomes and micro-aerobic zones.