Master of Science in Engineering Science (MSES)
Engineering Science (Interdepartmental Program)
In recent years, biofiltration technology has been used at numerous locations worldwide as an air pollution control technology for treating gases contaminated with low concentrations of biodegradable volatile organic compounds (VOCs). At the same time, there have been many reports in the literature of contaminant emissions from biofilters during transient loading conditions. There is currently a need to develop methods for controlling such emissions. Periodically operated bioreactors have been used successfully in treatment of wastewater and soils for several decades to mitigate the effects of uncontrolled unsteady-state loading on waste treatment systems. Such operating strategies have only recently been applied to biofilters treating gas-phase contaminants. Research described herein compared contaminant removal efficiency in biofilters subjected to periodic operating strategies to that of a conventional continuously loaded biofilter. Methy ethyl ketone (MEK), a compound that is regulated as a hazardous air pollutant (HAP) under the 1990 Clean Air Act amendments, was used as a model compound. Experiments were conducted to assess the ability of biofilters to remove MEK during quasi-steady state conditions (i.e., ¡°normal¡± operation) as well as during transient periods of elevated contaminant loading (i.e., ¡°shock loading¡± conditions). An influent MEK concentration of 106 ppmv was used for normal loading experiments while a concentration of five times that (530 ppmv) was applied during one-hour shock loading experiments. Shock loading experiments were conducted to evaluate both active and passive control techniques. Results reported herein demonstrate that controlled periodic operating strategies can enhance contaminant removal of MEK during transient periods of elevated contaminant load. Shock loading experiments testing active control strategies resulted in MEK removal efficiencies greater than 95% for the periodic systems, while ranging from 55 to 70% for the continuously loaded biofilter. Removal efficiencies for the periodically operated systems dropped to less than 30% during experiments conducted to assess biofilter response to uncontrolled contaminant loading in the absence of an active control strategy. Thus, while periodic operation coupled with an active control strategy can improve biofilter performance during at least some transient loading conditions, there is a clear need for adequate control systems if such an operating strategy is adopted.
Document Availability at the Time of Submission
Release the entire work immediately for access worldwide.
Norman, Charles William, "The effect of periodic operation on biofilters for removal of methyl ethyl ketone from contaminated air" (2002). LSU Master's Theses. 3545.
William M. Moe