Gaseous BTEX Biofiltration: Experimental and Numerical Study of Dynamics, Substrate Interaction and Multiple Steady States
AdvisorDe Visscher, Alex
Committee MemberSiegler, Hector
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AbstractAir pollution has a global impact on the environment and human health. In recent decades growing consciousness of air pollutants has led to a substantial decline in hazardous emissions. Nevertheless, air quality problems persist. A group of pollutants of particular concern are benzene, toluene, ethylbenzene and xylene, commonly referred to as BTEX. BTEX are known for their adverse effects on human health such as the carcinogenicity of benzene among others. Continuous development, improvement and exploring of new innovative control technologies are of great importance and striven for by researchers and industry. Biological methods such as biofilters are considered to be a sustainable and environmentally friendly technology. Hence, the present dissertation investigated the employment of a promising microorganism, Nocardia sp., to treat BTEX in a biofilter as well as the experimental and computational study of different steady states. At an empty-bed residence time (EBRT) of 1.5 min and an inlet concentration between 0.05 – 0.14 g m- 3 single benzene, toluene, ethylbenzene and m-xylene were removed with an efficiency of 100%, 93%, 96% and 87% respectively. With increasing inlet concentration, the removal efficiency (RE) declined, however an increase of EBRT generally resulted in higher RE. A similar trend was observed when BTEX were treated as a mixture and highest RE were achieved at low concentrations. In addition, the determination of kinetic parameters of the microorganism were carried out and the threshold substrate concentration for benzene and m-xylene were estimated. The exploration of a possible jump of steady states were numerically examined by considering only the biofilm. Therefore, two independent computer simulations were developed, which includes diffusion limitation and substrate degradation following Haldane kinetics. Results clearly indicate a jump of steady states in a very small range of inlet concentration and a distortion of prevailing Haldane kinetics. A further development of one model was carried out and aforementioned determined kinetic parameters were applied. This model correctly described the jump of steady states in an actual biofilter at a concentration change of 0.272 g m-3. Obtained results are supported by experimental validation.
Schulich School of Engineering