Three Vertical Flow Constructed Wetlands Filled with Different Packing Materials for Piggery Wastewater Treatment

Abstract

Seasonal performances of three vertical2flowconstructedwetlands (VFCWs) filled with different packing materials for piggery wastewater treatment was investigated. Results showed that there were no some significant seasonal differences in the COD removal efficiency among three types of VFCWs. Biodegradation of organic matter in all three VFCWs were found following the first order rate model. The N removal efficiencies in conventional VFCWs indifferent seasons constantly maintained at 52%. However, N removal efficiencies were found fluctuating over seasons in VFCWs filled with zeolite or zeolite cinder, 89.8% and 93.4% in autumn, 64.2% and 73.5% in winter, and around 80% in spring and summer, respectively. Total nitrogen (TN) removal efficiencies of all VFCWs in winter were considerably lower than those in the other seasons due to relatively weaker processes of nitrification-denitrification. The nitrification activity in VFCWs filled with zeolite2cinder was the highest among all of VFCWs, while the denitrification activity in VFCWs filled with zeolite or zeolite-cinder was more in tensive than that in the conventional VFCWs, agreeing with the TN removal efficiencies in three VFCWs. As packing material, zeolite is able to accelerate the process of denitrification as well as TN removal efficiencies of VFCWs.