Abstract
This study was conducted to assess the removal of arsenic (As) and heavy metals from mining wastewater by the combination of adsorption, using modified iron-ore drainage sludge, and horizontal-subsurface-flow constructed wetland with common reed (Phragmites australis). The pilot-scale experiment with a constant flow rate of 5 m3/day was operated for four months using real wastewater from a Pb–Zn mine in northern Vietnam. Atomic absorption spectroscopy was used for elemental analysis in wastewater and plant. X-ray diffraction (XRD), surface charge measurements (by a particle charge detector (PCD)), Fourier-transform infrared (FTIR), and surface area Brunauer–Emmet–Teller (BET) measurements were performed to determine the characteristics of the adsorbent. The results showed that the average removals of As, Mn, Cd, Zn, and Pb by the combined system with limestone substrate during four months were 80.3%, 96.9%, 79.6%, 52.9%, and 38.7%, respectively. The use of another constructed wetland substrate, laterite, demonstrated better removal efficiency of As than limestone. The concentrations of As and heavy metals in the effluent were lower than the limits established by the QCVN 40:2011/BTNMT for industrial wastewater, which indicated the feasibility of combining adsorption and constructed wetland for the treatment of mining wastewater.
Highlights
Mining activities release large amounts of solid wastes and wastewater into the surrounding environment
The present study aimed to evaluate the potential of using an adsorbent and Constructed wetland (CW) in removing As and heavy metals from the wastewater of Cho Don Pb–Zn mine
Fourier-transform infrared (FTIR), and surface area measurements were performed for the adsorbent
Summary
Mining activities release large amounts of solid wastes and wastewater into the surrounding environment. Any technology possesses both advantages and limitations, considering treatment effectiveness, installation, operational and maintenance cost, further treatment of secondary wastes, technical requirements, and time and space requirements [9,10]. Adsorption is considered a cost-effective method [11,12] when using adsorbents that require little processing or are industrial wastes or by-products [13]. The use of mining wastes as adsorbents is considered an environment-friendly technique with double benefits, as it allows to treat both solid wastes and contaminated water and to approach the ideal goal of waste-free production [14,15]
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