Abstract ID
nutdyn27
Type
Oral
Theme
nutdyn
Full title
Influence of intermittent feeding regime on water purification and greenhouse gas emissions from constructed
wetlands for wastewater treatment: An overview
Abstract text
Pulsing hydrology is a common phenomenon in coastal zones (especially in estuaries and tidal marshes) and
floodplains. Intermittent feeding that mimics the pulsing hydrology of natural wetlands is widely used in
constructed wetlands (CW). In our study we analysed the results of 152 papers on the effects of intermittent
loading on nutrient and organic material removal and greenhouse gas (GHG) emissions in CWs, indexed by the
ISI Web of Knowledge. Combinations of the terms “wetland(s)”, “intermittent”, “pulsing―,
“nitrogen”, “phosphor(o)us”, “methane”, and “nitrous oxide” occurring in titles,
abstracts, and key words were used. In addition, we used data from our earlier studies on wastewater treatment
efficiency of a batch-operating system and GHG emission from two hybrid CWs.In created riverine wetlands,
pulsing effects enhance sedimentation, nutrient removal and decrease emissions of methane (CH₄)
and nitrous oxide (N₂O). In terms of CWs for municipal, farming, and industrial/mining
wastewater treatment, intermittent loading is mainly used in vertical flow subsurface flow (VSSF) filters to
increase oxygen consumption. Some VSSFs operate as tidal flow systems. Likewise, batch-operated CWs,
reciprocating wetland systems, and horizontal subsurface flow (HSSF) filters with pulsing water levels provide
elevated oxygen supply for the mineralization of organic material and nitrification. Several studies on
wastewater treatment CWs demonstrate that intermittent loading increases organic material mineralization,
nitrogen and phosphorus removal, and the retention/transformation of various hazardous compounds.Little is
known about the effects of intermittent loading in CWs on the fluxes of CO₂, CH₄
and N₂O in CWs for wastewater treatment. Our earlier results show that CH₄
emission was significantly lower from intermittently fed VSSFs than from HSSFs with stable water level,
whereas N₂O and CO₂ emission was slightly higher from VSSF systems. Higher
N₂O and CO₂ release from intermittent VSSF beds is contradictory to the results
from studies on created riverine wetlands with pulsing hydrologic regime, but coincides with the results from
paddy fields with inter-season drainage. It appears that pulsing (feeding) frequency controls the emission of
N₂O, although further investigations should be conducted to achieve a better understanding of
pulsing effects on GHG emissions from CWs.
Submission date
2009-10-21
Keywords
Carbon dioxide; Horizontal subsurface flow filter; Methane; Nitrous oxide; Vertical subsurface flow filter
Will be submitting paper?
Yes