Full-Scale Experiment on Domestic Wastewater Treatment by Combining Artificial Aeration Vertical- and Horizontal-Flow Constructed Wetlands System

摘要

To improve domestic wastewater treatment for total nitrogen (TN) removal, a full-scale constructed wetlands combining an artificially aerated vertical- (AVCW) and a horizontal-flow constructed wetland (HCW) was completed in July 2007. The system covered a total area of 7,610 m~2. From 2 July 2007 to 7 August 2008, the treatment capacity was 2,076 m~3day~(-1) with an aeration quantity of 7,400 m~3 day~(-1). The system effectively reduced the average annual output of BOD_5 (52.0 %), NH_4-N (58.41 %), and TP (41.61 %), although the percentage reductions of other pollutants, including chemical oxygen demand (34.1 %), suspended solid (38.9 %), and TN (31.05 %) were lower. The purpose of the HCW was for denitrification of the effluent from the AVCW, and annual average of 34.27 % of NO3-N was removed compared with the reading at the AVCW outlet. With hydraulic loading increased to 4,152 m_3day~~(-1) from 9 September to 23 November 2007, the removal rate for NO_3-N from the HCW decreased substantially from 48.80 to 18.86 %. The total removal rates of NH_4-N showed significant positive correlation with DO content in the AVCW and with total TN removal rates for the combined system (P<0.05). The study indicated that, even with limited artificial aeration, nitrification was very effective for NH_4-N removal.