Effect of Loading Frequency on Ammonia-Nitrogen Removal Kinetics in Early-Stage Pilot-Scale Vertical Flow Constructed Wetlands Treating Landfill Leachate

Abstract

This study measured the effects of loading frequency and plant species on the removal of ammonia-nitrogen (NH3-N) in a vertical flow constructed wetland (VFCW). Eight pilot-scale VFCW columns were constructed for this experiment; half of the columns were planted with Typha latifolia and the other half Scirpus californicus. To test the effect of loading frequency, half of the columns for each plant species were fed diluted leachate over the course of 24 h, and the other half were fed diluted leachate over the course of 8 h. This study was conducted in the early stages of plant and biofilm development within the system. Removal of chemical oxygen demand (COD) was observed but inconsistent, as was denitrification. Average NH3-N removal efficiencies in the various configurations ranged from 39.4 to 55.1%, and all configurations experienced peak removal efficiencies at a 1:20 dilution of leachate. Columns planted with T. latifolia and fed over 24 h performed significantly better than those planted with S. Californicus; this effect was not observed for columns fed over 8 h. Of the four configurations, columns planted with T. latifolia and fed over the course of 24 h performed best. The mechanisms responsible for this deserve further study.