『Abstract
Phosphorus (P) releases to the environment have been implicated
in the eutrophication of important water bodies worldwide. Current
technology for the removal of P from wastewaters consists of treatment
with aluminium (Al) or iron (Fe) salts, but is expensive. The
neutralization of acid mine drainage (AMD) generates sludge rich
in Fe and Al oxides that has hitherto been considered a waste
product, but these sludges could serve as an economical adsorption
media for the removal of P from wastewaters. Therefore, we have
evaluated an AMD-derived media as a sorbent for P in fixed bed
sorption systems. The homogeneous surface diffusion model (HSDM)
was used to analyze fixed bed test data and to determine the value
of related sorption parameters. The surface diffusion modulus
Ed was found to be a useful predictor of sorption kinetics. Values
of Ed＜0.2 were associated with early breakthrough of P, while
more desirable S-shaped breakthrough curves resulted when 0.2＜Ed＜0.5.
Computer simulations of the fixed bed process with the HSDM confirmed
that if Ed was known, the shape of the breakthrough curve could
be calculated. The surface diffusion coefficient Ds
was a critical factor in the calculation of Ed and could be estimated
based on the sorption test conditions such as media characteristics,
and influent flow rate and concentration. Optimal test results
were obtained with a relatively small media particle size (average
particle radius 0.028 cm) and resulted in 96％ removal of P from
the influent over 46 days of continuous operation. These results
indicate that fixed bed sorption of P would be a feasible option
for the utilization of AMD residues, thus helping to decrease
AMD treatment costs while at the same time ameliorating the impacts
of P contamination.
Keywords: Acid mine drainage sludge; Eutrophication; Phosphorus
removal; Fixed bed sorption; Homogeneous surface diffusion model;
Wastewater; Iron oxide sorption media』
Nomenclature
1. Introduction
2. Methods and materials
2.1. Sorption media
2.2. Sorption capacity
2.3. Fixed bed testing
2.4. Modeling of fixed bed results
3. Results and discussion
3.1. Sorption capacity
3.2. Fixed bed testing - Effect of flow interruption
3.3. Fixed bed testing - Effect of influent flow rate and concentration
3.4. Fixed bed testing - Effect of media particle size
3.5. Fixed bed simulations
4. Summary and conclusions
Acknowledgments
References