VOC Emissions from Sewers Process Drains and Drop StructuresEPA Grant Number: R823335
Title: VOC Emissions from Sewers Process Drains and Drop Structures
Investigators: Corsi, Richard L.
Institution: The University of Texas at Austin
EPA Project Officer: Hahn, Intaek
Project Period: October 1, 1995 through September 1, 1998
Project Amount: $271,896
RFA: Exploratory Research - Engineering (1995) Recipients Lists
Research Category: Air Quality and Air Toxics , Engineering and Environmental Chemistry , Land and Waste Management
Description:As a result of the Clean Air Act of 1990, several industries are required to estimate emissions of hazardous air pollutants (HAPs) from on-site industrial sewers, and to control such emissions where appropriate. However, existing methods for estimating HAP emissions from sewer components are either non-existent or characterized by a high degree of uncertainty. The purpose of this project is to conduct a series of experiments to better understand the mechanistic behavior of HAP emissions from industrial process drains and sewer drop structures. Experimental data will be used to determine fundamental mass transfer parameters, with subsequent use of those parameters in a state-of-the-art computational model that will also be developed as part of this study.
Experimental studies will be completed in two separate phases. Phase I will involve the construction and application of an industrial drain simulator housed in an environmental chamber. A cocktail of five volatile HAP surrogates will be used to determine HAP stripping efficiencies and mass transfer coefficients over a wide range of chemical properties, fluid properties, and environmental conditions, e.g., temperature and wind. Experiments will be further divided into process drains with and without water seals.
Phase II experiments will involve the construction and use of an industrial drop simulator. The same cocktail of volatile tracers will be used to study HAP stripping efficiencies and mass transfer coefficients. A wide range of drop operating conditions will be studied, with particular attention given to correlating HAP mass transfer coefficients to power input, and HAP stripping efficiencies to oxygen transfer. Specific mechanisms of mass transfer, e.g., stripping by entrained air versus volatilization from a falling water film, will also be investigated.
The model that results from this study will allow both industry and the regulatory communities to develop improved HAP emissions estimates for specific industrial facilities or sectors. The mechanistic nature of the model will also be valuable for investigating passive control strategies that suppress HAP emissions.
The results of the study would: 1) assist EPA in the development of industry-specific NESHAPs, 2) provide the ability to routinely and accurately estimate VOC emissions from municipal and industrial wastewater, and 3) control VOC emissions by use of (hopefully) minor process changes to suppress gas-liquid mass transfer.