Vanadium Removal From Industrial Wastewaters
ROBERT G. KUNZ, Senior Environmental Engineer
JOSEPH F. GIANNELLI, Research Engineer
H. DAVID STENSEL, Manager, Wastewater Laboratory
Air Products and Chemicals, Inc.
Allentown, Pennsylvania 18105
INTRODUCTION
Vanadium may occur in industrial wastewater discharges from metal, petroleum, and
coal processing industries, often in conjunction with other heavy metals. Similar to other
heavy metals, vanadium is known to be toxic to aquatic life. In contrast, the effect of
vanadium on biological wastewater treatment systems was not previously reported. In
addition, information required for design of a vanadium removal system is insufficient and
scattered throughout the literature. The purpose of this investigation was to observe the fate
and inhibitory concentration of vanadium in a biological wastewater treatment system and
to determine a chemical/ physical treatment scheme for its removal. Such treatment could
be used prior to discharge to a receiving water, biological wastewater treatment system, or
municipal sewer.
Initially, the paper presents a summary of vanadium chemistry, necessary to
understand its occurrence and behavior in wastewater. Vanadium was found to have several
oxidation states and an amphoteric character. Laboratory tests revealed vanadium to be
initially taken up by activated sludge solids to the extent of 6.8 mg V/g MLSS without
adverse effects. Beyond this sorptive capacity, soluble vanadium appears in solution, and
begins to influence the microbial population and to inhibit waste stabilization activity at
about 20 mg 1. These results and an assumed yield coefficient of 0.65 were used to estimate a
wastewater V/BOD5 ratio of 4.4 lb/1,000 lb before vanadium would occur in an activated
sludge system effluent and 7.4 lb/1,000 lb before biological inhibition.
Based on standard laboratory jar tests with synthetic solutions, it was determined that
under neutral or alkaline conditions, vanadium can be removed to a 1-2 mg/l residual using
4 lb ferrous sulfate per lb vanadium. From these data, previously unreported solubility
products were obtained for FefVO,^ (Ksp = 3.75 x 10"12) and Fe V„0, (Ksp = 5 x 10"8). This
removal system was demonstrated on an actual wastewater.
Finally, activated carbon was shown to be feasible for vanadium removal. Carbon,
however, will probably be useful only for polishing operations because of the relatively low
equilibrium loading of 0.00016 lb V/lb carbon necessary to achieve a I mg/l or less
vanadium residual in solution.
In summary, relatively small quantities of vanadium can be effectively removed with
activated  sludge.   In  those cases where there is no activated sludge unit or higher
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