SHORT-TERM NITROGEN REMOVAL RATE BY MIXTUREOF AQUATIC PLANTS IN DIFFERENT HYDRAULICRETENTION TIMES OF CONSTRUCTED WETLANDS

摘要

The experimentTd(Thaliadealbata Fraser), p(Iris p s e u d a c o r u s L), Sv{ScirpusvalidusVahl) was based on short-term effects of species compositions (monocultures or two-species mixtures) and different hydraulic reten-tion times (H R T l, 2, 3 weeks) to nitrogen (N) removal rates in aquaculture wastewater of the con-structed wetlands (CWs). The results showed that(1) Plant compositions had different effects on N removal. In the NH4+ and TN removal, the removal rate had no difference between the monocultures and the two-species mixtures. W hile, the removal rate of two-species mixtures was significantly higher than that of monocultures in the No3_ re-moval (p < 0.05). It showed that two-species m ix-tures had a better N removal in the CWs than that of monocultures. (2) A longer HRT may have d if-ferent effect on plant N removal in the CWs. In the N H + removal, the monocultures and the two-species mixtures all reach the maximum in the 1st week. W hile in the No3_ and TN removal, the monocultures and the two-species mixtures reached the maximum in the diverse HRTs. (3) In monocul-tures, the No3_ removal rates ranged from 9.03% to 25.58%, while the N H +-N removal rates ranged from 7.08% to 71.2%, this proved that wetland plants may prefer ammonium (NH4+) over nitrate (No3_) in this study. It made lots of sense to choose the appropriate plant species and two-species m ix-tures to use for removing N pollutants in wastewater treatment engineering, and then showed two-species mixtures had a better N removal in the CWs than that of monocultures.