Continuous decontamination of metal-polluted mine water using engineered hybrid adsorbent

Abstract

Mining industries contribute enormously to water
pollution through discharge of effluents contaminated with
metals. Metals-polluted water is a threat to aquatic and human
lives as well as the general ecosystem. Numerous conventional
treatment methods are available for the removal of metals from
mine water, but majority of them are costly, inefficient for
trace metal concentration, and generate voluminous secondary
sludge. Therefore, there is need for alternative low-cost novel
technologies capable of reducing metal concentration in water
to acceptable levels. Adsorption technology is increasingly
receiving preference because it is simple in design, requires
low initial cost, easy to operate, can remove contaminants in
trace levels and the possibility to develop and employ wide
variety of adsorbents. This study, therefore, explored the
removal of manganese [Mn (II)] from aqueous solution using a
bentonite/metal oxide hybrid (B/MeOx/H) hydrogels adsorbent
packed in a fixed-bed reactor. The adsorption performance
was examined by breakthrough behaviors under various
experimental conditions such as bed height and influent flow
rate. It was found that increase in bed height resulted to
increase in both breakthrough and saturation times, while it
was opposite with influent flow rate. The breakthrough curves
were characterized by slightly flatter breakthrough curves for
large bed depth and low flow rate. The overall adsorption
performance of the fixed-bed column highly depended on the
operating parameters. The experimental breakthrough data was
sufficiently described by Yoon-Nelson model. Bed depth
service time (BDST) predicted well the breakthrough times for
different flow rates. The findings demonstrate that B/MeOx/H
hydrogel adsorbent could effectively polish mine water laded
with trace concentration of Mn (II).