Hexachlorobenzene dechlorination in constructed wetland mesocosms

• Published in: Water research (Oxford) Vol. 47; no. 1; pp. 102 - 110
• Main Authors: Zhou, Yuanqing, Tigane, Triin, Li, Xiuzhen, Truu, Marika, Truu, Jaak, Mander, Ülo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.01.2013; Elsevier
• Subjects: Applied sciences; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Biotechnology; Broad-leaved cattail; Chlorine - metabolism; Common reed; constructed wetlands; Construction; Dechlorinated metabolites; Dechlorination; Environment and pollution; Exact sciences and technology; floodplains; Fundamental and applied biological sciences. Psychology; HCB; Hexachlorobenzene; Hexachlorobenzene - chemistry; Industrial applications and implications. Economical aspects; Mathematical analysis; Other wastewaters; Peat; Phragmites; Phragmites australis; planting; Poaceae - physiology; Pollutants; Pollution; Rhizosphere; Roots; Sediments; Soil; Species Specificity; Typha; Typha latifolia; Typhaceae - physiology; wastewater treatment; Wastewaters; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Water Purification - methods; Water treatment and pollution; Wetlands; Eastern Europe; Europe; Estonia; Common reed; Rhizosphere; Broad-leaved cattail; Peat; HCB; Dechlorinated metabolites; Monocotyledones; Dehalogenation; Phragmites australis; Metabolite; Organic halogen compounds; Biological purification; Persistent organic pollutant; Dechlorination; Gramineae; Chlorocarbon; Angiospermae; Aquatic plant; Typha latifolia; Wetland; Hexachlorobenzene; Organic compounds; Organic chlorine compounds; Typhaceae; Halogenated hydrocarbon; Artificial medium; Spermatophyta; Waste water purification; Degradation product
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.09.030

We studied the dechlorination of hexachlorobenzene (HCB) in wetland mesocosm (MC) trials filled with sediment (well mineralized homogenized peat mixed with mud) from a wastewater treatment wetland located in a floodplain: three MCs were planted with common reed (Phragmites australis) and another three with broad-leaved cattail (Typha latifolia). According to the rootzone development we distinguished between the upper (0–10 cm from the soil surface) and lower layers (20–30 cm). Over 36 days, the initial measured concentration of HCB was reduced to 61%, 51%, 42% and 40% in the lower layer without roots of Phragmites, in the lower layer with roots of Typha, in the upper layer with roots of Typha, and in the upper layer with roots of Phragmites respectively. The 90% degradation time (DT90) of the initial measured HCB can be calculated as 192, 121, 110 and 92 days (d) respectively. PeCB, 1, 2, 3, 4-, 1, 2, 3, 5- and 1, 2, 4, 5-TeCB, and 1, 2, 3-, 1, 2, 4- and 1, 3, 5-TCB were the main dechlorination products detected in MC sediment samples. The dechlorination rates of HCB were higher in sediment layers with well-developed root zones. According to the DT50 of 28–58 days and DT90 of 92–192 days, HCB can be considered to be a less persistent organic pollutant in constructed wetlands. ► Dechlorination of hexachlorobenzene (HCB) in wetland mesocosms was studied. ► HCB concentration was reduced to 40–61% of initial value during 36 days. ► The dechlorination rates of HCB were higher in layers with well-developed root zones.