The relationship between two wetland systems (planted, unplanted) and their relationship to concentration of three malodorous compounds (dimethyl disulfide, ethyl acetate, p – cresol) was studied. Eight subsurface flow wetlands (4 planted, 4 unplanted) were treated liquid swine manure that was filtered through bark bed in order to reduce the total solids content. A human sensory panel was set up to evaluate the wetland effluent odour, and the reduction of the malodrous gas compounds was quantified using gas chromatography.

ANOVA analysis revealed a significant decrease in malodrous compounds in the planted wetland plots relative to the unplanted plots. On average, the planted wetlands removed between 60 – 80% of malodorous compounds, while the unplanted plost remobed between 35 – 70%. Sign tests of the odour anel indicate the intensity level ranking was <1 for the planted wetland structure, signifying no objectional effluent smell from the filtered swine wetland effluent.. In conclusion, planted wetlands outperformed unplanted wetlands at removing malodorous compounds from liquid swine manure and producing wetland effluent that was not objectional to the sensory panel.