The effect of a duckweed cover on sulphide volatilisation from waste stabilisation ponds

• Published in: Ecological engineering Vol. 35; no. 10; pp. 1501 - 1506
• Main Authors: Kerstens, S.M., van der Steen, N.P., Gijzen, H.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2009
• Subjects: Algae; Bacteria; Beggiatoa; Beggiatoa sp; Duckweed; Ecology; Freshwater; Lemna gibba; Ponds; Sulfides; Sulfur; Sulphide; Waste stabilisation ponds; Wastes; Lemna gibba; Sulphide; Duckweed; Waste stabilisation ponds; Beggiatoa sp
• ISSN: 0925-8574; 1872-6992
• DOI: 10.1016/j.ecoleng.2009.06.008

The effects of a duckweed (DW) cover on the surface of waste stabilisation ponds on sulphide emissions were studied in a laboratory scale set-up of an anaerobic pond-reactor, followed by two algae ( A) pond-reactors and two duckweed ( Lemna gibba) pond-reactors. The concentrations of various S-components were measured at different depth in the reactors, while sulphide emissions were measured at the surface. Presence of a duckweed cover on the anaerobic pond-reactor resulted in a reduction of 99% in sulphide emission. In algae pond-reactors, sulphide emissions were negligible through chemical and biological conversion of sulphide. In the duckweed pond-reactors, colourless sulphur bacteria ( Beggiatoa sp.) were observed on the duckweed roots. Batch tests showed that both micro-biological and possibly chemical oxidation occurred in a typical duckweed pond environment. The duckweed cover reduced H 2S volatilisation via two mechanisms, by forming a physical barrier and by providing attachment area for sulphide oxidising bacteria.