Journal Article

Effects of sorption, sulphate reduction, and Phragmites australis on the removal of heavy metals in subsurface flow constructed wetland microcosms

Lesage, E, Moortel, A. van de, Tack, F.M.G, Pauw, N. de, Verloo, M.G, Rousseau, D.P.L

2007

Overview

The removal of Co, Ni, Cu and Zn from synthetic industrial wastewater was studied in subsurface flow constructed wetland microcosms filled with gravel or a gravel/straw mixture. Half of the microcosms were planted with Phragmites australis and half were left unplanted. All microcosms received low-strength wastewater (1 mg L−1 of Co, Ni, and Zn, 0.5 mg L−1 Cu, 2,000 mg L−1 SO4) during seven 14-day incubation batches. The pore water was regularly monitored at two depths for heavy metals, sulphate, organic carbon and redox potential. Sorption properties of gravel and straw were assessed in a separate experiment. A second series of seven incubation batches with high-strength wastewater (10 mg L−1 of each metal, 2,000 mg L−1 SO4) was then applied to saturate the substrate. Glucose was added to the gravel microcosms together with the high-strength wastewater. Sorption processes were responsible for metal removal during start-up, with the highest removal efficiencies in the gravel microcosms. The lower initial efficiencies in the gravel/straw microcosms were presumably caused by the decomposition of straw. However, after establishment of anaerobic conditions (Eh∼−200 mV), precipitation as metal sulphides provided an additional removal pathway in the gravel/straw microcosms. The addition of glucose to gravel microcosms enhanced sulphate reduction and metal removal, although Phragmites australis negatively affected these processes in the top-layer of all microcosms.

• Publisher: IWA Publishing
• Subject: Adsorption / Anaerobic conditions / Anoxic conditions / Aquatic plants / Artificial wetlands / Biodegradation, Environmental / carbon / chemical precipitation / chemistry / Cobalt / constructed wetlands / Copper / Freshwater plants / Glucose / Gravel / Heavy metal removal / Heavy metals / High strength / Incubation period / industrial effluents / Industrial wastes / Industrial wastewater / isolation & purification / Marshes / Metal sulfides / Metals, Heavy / Metals, Heavy - isolation & purification / methods / Microcosms / Nickel / Organic carbon / Oxidoreductions / Phragmites australis / phytoremediation / Pore water / Redox potential / reduction / Removal / Sorption / Straw / Substrates / subsurface flow / Sulfate reduction / Sulfates / Sulfates - chemistry / sulfides / Sulphate reduction / Sulphates / Sulphides / Waste Disposal, Fluid / Wastewater / wastewater treatment / Water Movements / Water Purification / Water Purification - methods / wetland plants / Wetlands / Zinc
• ISBN: 9781843395980, 1843395983