title: Comparison of vertical-flow constructed wetlands with and without supplementary aeration treating decentralized domestic wastewater.
abstract: Constructed wetlands (CWs) are efficient in reducing excessive contamination from wastewaters. However, oxygen inside CW beds is frequently low especially when substrate clogging problems appear after long-term operation, and this may become a limited factor for the treatment of wastewaters. Aimed at dealing with the issue of a low oxygen content in CW systems, two laboratory-scale vertical-flow constructed wetlands (VFCWs) with and without an aeration device (called VFCW-a and VFCW-c, respectively) were designed in this study to test the contribution of supplementary aeration to the treatment of decentralized domestic wastewater. Results showed that under the intermittent operation of about 45 days, two VFCW units were successfully started up by using activated sludge as seed sludge. Compared to VFCW-c, VFCW-a had a better resistance ability to organic shock loads and its removal function could be effectively recovered within a short period after the introduction of organic shock loads. Under intermittent operation with a 12 h idling time, the ideal hydraulic retention time (HRT) of VFCW-a was 42 h, about 6 h shorter than that of VFCW-c. Likewise, under intermittent operation with 42 h HRT, the ideal idling time of VFCW-a was 12 h, still about 6 h shorter than that of VFCW-c. Under intermittent operation with HRT-42 h and an idling time of 12 h, SS, COD, TN and TP removal efficiencies in VFCW-a could reach 81.2%, 85%, 89.9% and 77.9%, respectively. The VFCW unit with supplementary aeration is an efficient innovation for the treatment of decentralized domestic wastewater.
authors.affiliation: Hubei University, Faculty of Resources and Environment, Wuhan, China. zliand@uwasa.fi
authors.forename: Liandong
authors.initials: L
authors.lastname: Zhu
authors.forename: Josu
authors.initials: J
authors.lastname: Takala
authors.forename: Erkki
authors.initials: E
authors.lastname: Hiltunen
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Li
authors.forename: Yohanes
authors.initials: Y
authors.lastname: Kristianto
mesh_terms: D010100:Oxygen; D014872:Water Movements; D018508:Water Purification; D053833:Wetlands
chemical_list: D010100:Oxygen