Suka Chuersuwan, Pongthep Suwanwaree, and Nares Chuersuwan

pp. 367 - 373

Abstract

Methane (CH₄
), nitrous oxide (N₂O) and carbon dioxide (CO₂
) fluxes were evaluated from constructed wetlands (CWs)
used to improve domestic wastewater quality. Experiments employed subsurface flow (SF) and free water surface flow (FWS)
CWs planted with Cyperus spp. Results showed seasonal fluctuations of greenhouse gas fluxes. Greenhouse gas fluxes
from SF-CWs and FWS-CWS were significantly different (p<0.05) while pollutant removal efficiencies of both CWs were not
significantly different. The average CH₄
, N₂O and CO₂
 fluxes from SF-CWs were 2.9±3.5, 1.0±1.7, and 15.2±12.3 mg/m²
/hr,
respectively, corresponding to the average global warming potential (GWP) of 392 mg CO₂
 equivalents/m²
/hr. For FWS-CWs,
the average CH₄
, N₂O and CO₂
 fluxes were 5.9±4.8, 1.8±1.0, and 29.6±20.2 mg/m²
/hr, respectively, having an average GWP of
698 mg CO₂
 equivalents/m²
/hr. Thus, FWS-CWs have a higher GWP than SF-CWs when they were used as a system for
domestic water improvement.