Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1002/elsc.200800093 |
| Title (Primary) | Redox dynamics of arsenic species in the root-near environment of Juncus effusus investigated in a macro-gradient-free rooted gravel bed reactor |
| Author | Rahman, K.Z.; Wießner, A.; Kuschk, P.; Mattusch, J.; Offelder, A.; Kästner, M.; Müller, R.A. |
| Journal | Engineering in Life Sciences |
| Year | 2008 |
| Department | UBT; ANA; UBZ |
| Volume | 8 |
| Issue | 6 |
| Page From | 612 |
| Page To | 621 |
| Language | englisch |
| Keywords | Arsenic removal; Arsenic species; Artificial wastewater; Laboratory-scale constructed wetlands |
| Abstract | In the framework of investigating the dynamics of As species within the planted soil beds of treatment wetlands, the redox dynamics of As species particularly in the root-near environment of the rhizosphere were investigated. For this purpose, long-term experiments were carried out using a specially designed macro-gradient-free rooted gravel bed reactor, planted with Juncus effusus to treat an artificial wastewater containing As (200 g As/L). The exceptional quality of the biofilm processes at the helophyte root-surfaces in treatment wetlands were of special importance in this investigation. The results showed that under C-deficient conditions, a highly efficient As immobilization (> 85 %), obviously due to adsorption and/or co-precipitation, was attained. The addition of organic carbon immediately caused an elevated As concentration and enrichment of As(III) (nearly 80 % of total As) in the reactor. Increasing the SO42- concentration in the artificial wastewater inflow facilitated a high As immobilization (> 82 %) under sulfate reducing condition. In principle, a highly efficient microbial dissimilatory sulfate reduction contributed to S2- formation and a greater As immobilization (most likely as As2S3) under C surplus and reducing conditions. Significant differences in As immobilization were observed by varying the inflow of the SO42- concentration (0.2, 5, 10, 25 S/L) under C surplus conditions. More As(III) precipitates (15 % less in the outflow) when the inflow of the SO42- concentration was decreased from 25 mg S/L to 10 mg S/L. Immobilized As showed greater instability by releasing As(V) (up to 85 % of total As) due to changes in the dynamic redox conditions inside the reactor. Re-oxidation of reduced sulfur into other S species (e.g. S0, SO42-) due to plant-root mediated O2 release probably caused an oxidative dissolution of already precipitated insoluble As (e.g. As2S3) and as a consequent As remobilization. The findings of this study highlighted the significance of SO42- in relation to organic C supply in planted soil beds treating As-contaminated wastewater under constructed wetland conditions. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=1333 |
| Rahman, K.Z., Wießner, A., Kuschk, P., Mattusch, J., Offelder, A., Kästner, M., Müller, R.A. (2008): Redox dynamics of arsenic species in the root-near environment of Juncus effusus investigated in a macro-gradient-free rooted gravel bed reactor Eng. Life Sci. 8 (6), 612 - 621 |
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