48    TREATMENT OF BTEX AND PETROLEUM HYDROCARBON
VAPORS USING A FIELD-PILOT BIOFILTER
A. Paul Togna, Manager, Air Toxics Program
George J. Skladany, Manager, Technology Applications
James M. Caratura, Senior Project Manager
Envirogen, Inc.
Princeton Research Center
Lawrenceville, New Jersey 08648
INTRODUCTION
Vapor extraction has been shown to be an effective means of remediating hydrocarbon-
contaminated soils and groundwater at hazardous waste sites and at facilities with leaking underground storage tanks. However, the hydrocarbon-contaminated vapors produced from these operations often must be treated before being discharged to the atmosphere. For many soil vapor extraction
(SVE) applications, biofiltration has the potential to be a less expensive alternative to conventional air
treatment technologies such as catalytic incineration and carbon adsorption. However, the lack of
full- and pilot-scale data limits the general acceptance and use of biofiltration for remediation applications.
To help fill the need for economic, design, and regulatory compliance data, a field-pilot biofilter
containing 30 cubic feet of packing material, acclimated for six months on actual SVE vapors during a
previous project, was used to evaluate the effectiveness of using biofiltration to treat air contaminated
with gasoline. The field-pilot study was designed to evaluate the removal efficiency of individual
benzene, toluene, ethylbenzene, and xylene (BTEX) components, as well as total petroleum hydrocarbons (TPH), at concentrations observed during the operation of actual SVE systems.
BACKGROUND
Biofiltration is a process that utilizes microorganisms immobilized in the form of a biofilm layer on
a porous, absorbent filter packing material such as compost or peat. As a contaminated vapor stream
passes through the filter bed, pollutants are transferred from the vapor phase to the biolayer and are
oxidized, forming carbon dioxide and water, or, in the case of odors, are transformed into less- or
non-odorous compounds.
Biofiltration has been used in Europe for over 30 years to control odorous air emissions.1 Biofilters
have also been used in the United States to treat hydrogen sulfide, mercaptans, alcohols, and other
odor-causing air-borne contaminants emitted from wastewater treatment plants, industrial process
streams, and composting facilities.2"4 Recent advances in biofilter technology have expanded the
range of treatable target compounds to include many VOCs and air toxics as well.1,5"7
One such advance has been the development of biofilters to treat petroleum hydrocarbon
vapors.8"" Vapor extraction technologies are becoming a preferred method for remediating
hydrocarbon-contaminated soils and groundwater. In cases where off-gases are produced containing
high concentrations of hydrocarbons, biofiltration has the potential to be a cost effective alternative
to conventional air treatment technologies such as incineration and carbon adsorption.
The tests described herein follow an in-depth six month biofilter evaluation performed for the
Petroleum Environmental Research Forum (PERF) to determine the feasibility and effectiveness of
using biofiltration to treat actual SVE vapor discharges.12 The PERF testing program was designed to
obtain BTEX and TPH removal efficiencies as a function of vapor contact time so that an economic
evaluation of biofiltration for hydrocarbon applications could be prepared. After that demonstration
project was completed, the field-pilot biofilter was returned to ENVIROGEN, and the performance
of the system was further evaluated using a synthetic unleaded gasoline-contaminated vapor stream.
49th Purdue Industrial Waste Conference Proceedings, 1994 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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