TY - JOUR
T1 - Constructed wetlands for steel slag leachate management
T2 - Partitioning of arsenic, chromium, and vanadium in waters, sediments, and plants
AU - Gomes, Helena I.
AU - Mayes, William M.
AU - Whitby, Paul
AU - Rogerson, Mike
PY - 2019/8/1
Y1 - 2019/8/1
N2 - Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate)or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V)are removed in constructed wetlands and how they accumulate in the sediments and the plants (Phragmites australis, common reed). The results show that reedbeds were very effective at removing calcium (98%), aluminium (81%), barium (98%), chromium (90%), gallium (80%), nickel (98%), and zinc (98%), and lowering pH and alkalinity. No statistical difference was found for As and V between leachate influent and wetland samples, showing that these metal(loid)s were not efficiently removed. As, Cr, and V were significantly higher in the reedbed sediments than in a reference site. However, sediment concentrations are not at levels that would pose a concern regarding reuse for agricultural purposes (average values of 39 ± 26 mg kg −1 for As, 108 ± 15 mg kg −1 for Cr, and 231 ± 34 mg kg −1 for V). Also, there is no significant uptake of metals by the aboveground portions of the reeds compared to reference conditions. Results show statistically significant enrichment in metal(loid)s in rhizomes and also a seasonal effect on the Cr concentrations. The data suggest minimal risk of oxyanion-forming element uptake and cycling in wetlands receiving alkaline steel slag.
AB - Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate)or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V)are removed in constructed wetlands and how they accumulate in the sediments and the plants (Phragmites australis, common reed). The results show that reedbeds were very effective at removing calcium (98%), aluminium (81%), barium (98%), chromium (90%), gallium (80%), nickel (98%), and zinc (98%), and lowering pH and alkalinity. No statistical difference was found for As and V between leachate influent and wetland samples, showing that these metal(loid)s were not efficiently removed. As, Cr, and V were significantly higher in the reedbed sediments than in a reference site. However, sediment concentrations are not at levels that would pose a concern regarding reuse for agricultural purposes (average values of 39 ± 26 mg kg −1 for As, 108 ± 15 mg kg −1 for Cr, and 231 ± 34 mg kg −1 for V). Also, there is no significant uptake of metals by the aboveground portions of the reeds compared to reference conditions. Results show statistically significant enrichment in metal(loid)s in rhizomes and also a seasonal effect on the Cr concentrations. The data suggest minimal risk of oxyanion-forming element uptake and cycling in wetlands receiving alkaline steel slag.
KW - Alkaline drainage
KW - Passive treatment
KW - Phragmites australis
KW - Reedbeds
KW - Sediments
UR - http://www.scopus.com/inward/record.url?scp=85065232045&partnerID=8YFLogxK
U2 - 10.1016/j.jenvman.2019.04.127
DO - 10.1016/j.jenvman.2019.04.127
M3 - Article
C2 - 31078927
AN - SCOPUS:85065232045
SN - 0301-4797
VL - 243
SP - 30
EP - 38
JO - Journal of Environmental Management
JF - Journal of Environmental Management
ER -