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Redox Properties of a Constructed Wetland: Theoretical and Practical Aspects
Author(s) -
Šíma Jan,
Diáková Kateřina,
Pavelcová Lenka,
Havelka Michal
Publication year - 2009
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.200800096
Subject(s) - peat , redox , wetland , aeration , bog , transect , inflow , constructed wetland , chemistry , environmental chemistry , anoxic waters , phosphorus , vegetation (pathology) , outflow , wastewater , soil science , hydrology (agriculture) , environmental science , environmental engineering , ecology , geology , inorganic chemistry , geotechnical engineering , medicine , oceanography , organic chemistry , pathology , biology
Constructed wetlands represent a progressive approach to the wastewater treatment. A fundamental prerequisite of the efficient water quality improvement is the presence of redox potential gradients (connected with the aeration of the system) inside the vegetation bed. Redox properties of a constructed wetland were tested in three longitudinal transects crossing the vegetation bed from the inflow zone to the outflow using diverse indicators ( e.g. , Fe III /Fe II , SO $\rm{ {_{4}^{2-}}}$ /S 2− ). Approximately 10–25% of iron was reoxidized in samples taken 10 m from the inflow zone in 2006. Redox processes of iron in artificial (constructed wetland) and natural (peat bog) ecosystems were compared. The peat bog was characterized with higher percentages of Fe II (usually ca. 90–100%). Thus, the aeration of the peat land was lower in comparison with the constructed wetland. The constructed wetland efficiently reduced sulfates (average concentrations of 44.7 and 11.2 mg/l at the inflow and the outflow, resp., in 2007). Organics, expressed as COD Cr and BOD 5 , and NH $\rm{ {_{4}^{+}}}$ were removed with efficiencies of 86.4, 92.2, and 60.4%, respectively. However, total phosphorus (redox processes play a negligible role in this case) was removed only with 39.6% efficiency. Redox properties of the wetland did not significantly depend on the heterogeneity of the treated wastewater flow.