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Title (Primary) Dynamics of Fe(II), sulphur and phosphate in pilot-scale constructed wetlands treating a sulphate-rich chlorinated hydrocarbon contaminated groundwater
Author Wu, S.; Chen, Z.; Braeckevelt, M.; Seeger, E.M.; Dong, R.; Kästner, M.; Paschke, H.; Hahn, A.; Kayser, G.; Kuschk, P.;
Journal Water Research
Year 2012
Department UBT; ANA;
Volume 46
Issue 6
Language englisch;
Keywords Constructed wetland; Sulphide toxicity; Ferrous iron; Phosphorus; Nitrification inhibition
Abstract

Long-term investigations were carried out in two pilot-scale horizontal subsurface flow constructed wetlands (planted and unplanted) with an iron-rich soil matrix for treating sulphate-rich groundwater which was contaminated with low concentrations of chlorinated hydrocarbons. The temporal and spatial dynamics of pore-water sulphide, Fe(II) and phosphate concentrations in the wetland beds were characterized and the seasonal effects on sulphide production and nitrification inhibition were evaluated. The results demonstrated that the pore-water sulphide concentrations gradually increased from less than 0.2 mg/L in 2005 to annual average concentrations of 15 mg/L in 2010, while the pore-water Fe(II) concentrations decreased from 35.4 mg/L to 0.3 mg/L. From 2005 to 2010, the phosphate removal efficiency declined from 91% to 10% under a relatively constant inflow concentration of 5 mg/L. The pronounced effect of plants was accompanied by a higher sulphate reduction and ammonium oxidation in the planted bed, as compared to the unplanted control. A high tolerance of plants towards sulphide toxicity was observed, which might be due to the detoxification of sulphide by oxygen released by the roots. However, during the period of 2009–2010, the nitrification was negatively impacted by the sulphide production as the reduction in the removal of ammonium from 75% to 42% (with inflow concentration of 55 mg/L) correlated with the increasing mean annual sulphide concentrations. The effect of the detoxification of sulphide and the immobilization of phosphate by the application of the iron-rich soil matrix in the initial years was proven; however, the life-span of this effect should not only be taken into consideration in further design but also in scientific studies.
ID 12246
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=12246
Wu, S., Chen, Z., Braeckevelt, M., Seeger, E.M., Dong, R., Kästner, M., Paschke, H., Hahn, A., Kayser, G., Kuschk, P. (2012):
Dynamics of Fe(II), sulphur and phosphate in pilot-scale constructed wetlands treating a sulphate-rich chlorinated hydrocarbon contaminated groundwater
Water Res. 46 (6), 1923 - 1932