Water, Air, & Soil Pollution

, Volume 223, Issue 8, pp 5105–5117

Fixed Bed Sorption of Phosphorus from Wastewater Using Iron Oxide-Based Media Derived from Acid Mine Drainage

Article

DOI: 10.1007/s11270-012-1262-x

Cite this article as:
Sibrell, P.L. & Tucker, T.W. Water Air Soil Pollut (2012) 223: 5105. doi:10.1007/s11270-012-1262-x

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 aluminum (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 homogenous 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 sludgeEutrophicationPhosphorus removalFixed bed sorptionHomogenous surface diffusion modelWastewaterIron oxide sorption media

Nomenclature

Bi

Biot number (dimensionless)

C

Solution phase concentration (M/L3)

C0

Influent solution concentration (M/L3)

Dg

Solute distribution parameter (dimensionless)

DRP

Dissolved reactive phosphorus (M/L3)

Ds

Surface diffusion coefficient (L2/t)

EBCT

Empty bed contact time (t)

Ed

Surface diffusion modulus (dimensionless)

HLR

Hydraulic loading rate (L/t)

KF

Freundlich isotherm coefficient ((L3/M)n)

kf

Liquid phase mass transfer coefficient (L/t)

m

Mass of adsorbent (M)

n

Freundlich isotherm exponent (dimensionless)

q

Solid phase concentration (M/M)

qe

Solid phase concentration at equilibrium (M/M)

Q

Liquid flow rate (L3/t)

Rpart

Sorbent particle radius (L)

St

Stanton number (dimensionless)

t

Time (t)

tsat

Ideal time to media saturation (t)

T

Normalized time (dimensionless)

ρp

Density of sorbent particle (M/L3)

Copyright information

© Springer Science+Business Media B.V. (outside the USA) 2012

Authors and Affiliations

  1. 1.US Geological SurveyLeetown Science CenterKearneysvilleUSA
  2. 2.IAP World ServicesKearneysvilleUSA