PhD, University of Cincinnati, 2007, Engineering : Environmental Engineering

Fluctuations in influent concentrations and variations in waste air composition challenge the application of biofiltration technology in the chemical industry. An integrated system of a cyclic 2-bed adsorption/desorption unit and a trickle bed air biofilter (TBAB) is proposed and applied in this study. The primary goal of the study was to maintain long-term, stable consistent high performance of volatile organic compounds (VOCs) degradation in the TBAB. Five specific studies were conducted to accomplish the primary objective. Investigations were conducted on independent TBABs under single VOC interchange with periodic backwashing as biomass control. The VOCs considered were common solvents used in paint booth industries. Two aromatic compounds (styrene and toluene) and two aliphatic compounds (Methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK)) were studied. This study simulated VOC emission rotation as the process of production rotated in certain chemical industries. Experimental findings indicated that the biofilter required apparent re-acclimation period when the VOC was interchanged to aromatic ones. The second phase investigated two mixtures of these VOCs in two independent parallel trains of TBAB under step change in influent concentration. Critical loadings were determined under backwashing and starvation operating strategies. In the third phase, the buffering capacity of a cyclic 2-bed adsorption unit under a square wave of fluctuating condition was evaluated for a feeding composition based on EPA industrial emission report. The cyclic 2-bed adsorption unit succeeded in attenuating load fluctuations as compared to non-cyclic operations. Furthermore, the time to breakthrough of contaminants encountered in non-cyclic operations could lead to a starvation period to the followed biofilter and eventually long period of acclimation after breakthrough of VOCs from the adsorber. In the fourth phase, the integrated system of 2 cyclic adsorption/desorption be (open full item for complete abstract)

Committee: Dr. George Sorial (Advisor) Subjects: Engineering, Environmental

PhD, University of Cincinnati, 1999, Engineering : Environmental Engineering

Increasing regulatory pressure for VOC emissions reduction has accelerated the development of more cost effective VOC air pollution control (APC) technologies. Biofiltration is a viable technology to fill this role, for the purification of air streams polluted with biodegradable VOCs. In the biofilter, these pollutants diffuse from the air stream into a stationary mass of moist biological film, where they are oxidized by enzymatic catalysis at ambient pressures and temperatures. Properly operated, this natural, biological mineralization process will produce only benign by-products, such as inorganic salts, carbon dioxide, and water, with some additional biomass. Although research into the science and development of the technology of biofiltration has been performed for over fifteen years, biofiltration remains not widely accepted as a proven technology for VOC APC. This perception is especially true for applications treating high influent VOC concentrations and requiring high VOC removal efficiencies. This research was undertaken to develop a new, cost effective biofiltration technology which can reliably treat air streams polluted with high VOC concentrations and achieve very high removal (elimination) efficiencies. Investigations were made to evaluate different biological attachment media, in order to identify the medium most suited to such an application. Using this medium, a reliable biofiltration technology was developed and extensively tested, which can achieve the goal of reliably treating high concentrations of VOCs at high loadings with high removal efficiency. Techniques for the management and control of the accumulating by-product biomass were developed. Procedures are presented for the calculation of VOC solubility and biological kinetic parameters, at the biofiltration operating temperature. A procedure for estimating the upper limit for biofiltration for the influent air VOC concentrations is presented. A simple, explicit biofilter design equation was (open full item for complete abstract)

Committee: Makram Suidan (Advisor) Subjects: