Environmental Engineering Reference
In-Depth Information
ies on the capacity of furnace sludge to remove metals from multi-metal solutions as
well as real leachate and groundwater have been suggested.
The aim of this project was to investigate the potential of blast-furnace sludge as
an adsorbent for metal contaminated water. The sludge was tested under extreme
conditions that can occur in real environments by means of laboratory studies to
determine the sorption capacity for metals (i) in multi solutions at different pH val-
ues and (ii) on an old sludge with multi-metals in real leachate
.
Experimental and Methods
The blast-furnace sludge used in this study was from a Swedish steel producer and
delivered by SSAB Merox AB in Oxelösund (a subsidiary of SSAB Svenskt Stål).
The company's activities are concentrated on recycling and the sale of non-steel
products from steel making processes.
Characterization of the Blast-Furnace Sludge
The crystalline components present in the blast-furnace sludge were studied qualita-
tively by x-ray powder diffraction (XRD) using a Siemens D5000 diffractometer and
Cu Ka radiation. The compounds were identified by comparison with standards in
the Joint Committee of Diffractions Standards database.
The buffer capacity of the furnace-sludge material was determined by 20 g of
sludge added to 40 mL deionised and filtrated (Milli-Q) water, after which 0.1 M
NaOH was added until the pH reached 12, after which 0.1 M HCl was added until
the pH dropped to 6.0. The same procedure was used for the old sludge material with
the addition of 8.7 g of material into 100 mL Milli-Q water and titration to pH 6.0.
This titration was slow and continued for 14 days. The carbonate alkalinity of the
old material was determined in a water solution after 5.0 g of the material had been
in contact with 500 mL of Milli-Q water for 24 h. The carbonate concentration was
calculated from the alkalinity by means of equilibrium calculations.
Sorption Beaker Tests
Sorption beaker tests were carried out to investigate the blast-furnace sludge sorption
capacity at different pH values for multi-metal solutions in concentrations equal to
extremely contaminated groundwater, see Table
1
. The goal was to investigate the
material's sorption capacity under extreme conditions that could occur in real-life
environments. The sorption tests were carried out by means of batch beaker tests in
which 5.00 g of dry sludge was added to each beaker. The sludge samples were
mixed in 500 mL of Milli-Q water at pH values of 5.6; 7.0 and ~9 over a 24 h period.
