12    EVALUATION OF CARBON IMPREGNATED
POLYURETHANE FOAM MEDIA FOR BIOLOGICAL
REMOVAL OF CARBON AND NITROGEN FROM
CHEMICAL INDUSTRY WASTEWATER
Silas W. Givens, Project Engineer
Industrial Processes and Hazardous Wastes
CH2M HILL
Atlanta, Georgia 30303
William A. Sack, Professor
Department of Civil Engineering
West Virginia University
Morgantown, West Virginia 26506
INTRODUCTION
In attempts to upgrade the activated sludge process, use of porous biomass support systems have
been employed to support microorganisms allowing a significant increase in biomass concentration.
These systems use large numbers of open celled polyurethane foam pads to support microorganisms.
The pad pore structure is such that substrate and oxygen pass through the pad with the establishment
of a differential velocity between the pads and the bulk liquid.
Porous biomass support systems (PBSS) have been in the developmental stages for a number of
years and are considered one of the emerging innovative and alternative (1/A) wastewater treatment
technologies by the U.S. EPA.' However, operational data is limited and little if any data is available
on the use of PBSS for the treatment of priority pollutants or for other advanced wastewater
treatment applications.
This laboratory study was undertaken to evaluate the performance of a PBSS utilizing a carbon
impregnated polyurethane foam pad for removal of priority pollutants and nitrogen. The addition of
activated carbon to the polyurethane pads is a unique modification of PBSS technology which is
believed to be advantageous for the treatment of toxic and inhibitory wastewater for both priority
pollutant and nitrogen removal.
BACKGROUND
The PBSS technology has been developed independently in the United Kingdom and West Germany
over a period of approximately 9 years. In the United Kingdom, researchers at the University of
Manchester Institute of Science and Technology developed what is now commercially marketed as the
Captor Process by Simon-Hartley, Ltd. In West Germany, Linde AG has developed what is known as
the Linpor Process. Both the Captor and Linpor processes use polyurethane foam pads within the
aeration basin; however, the processes differ in both pad size and operational configuration.'
Captor Process
The Captor process utilizes polyurethane pads of the approximate dimensions 25 mm x 25 mm x
12.5 mm. Normal basin pad concentration is 40,000 per m3, or a volume concentration of 31%.'
Because of the microorganisms ability to colonize surfaces, the pads become loaded with biomass to a
level which is a function of the strength of the wastewater. Typically, 60 to 300 mg of biomass per pad
are encountered which yields an "equivalent" mixed liquor suspended solids (MLSS) concentration
(neglecting non-pad solids) of 1860 to 9300 mg/L at a basin pad concentration of 31 pads/L.' The
"free" MLSS concentrations are intended to be negligible in the Captor process, thereby eliminating
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