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Effects of RTD and packing on methanol oxidation in a trickling biofilter

University of British Columbia

This research was initially focused on the study of the effects of RTDs on biotrickling filter systems and the comparison of the maximum EC and poisoning limits as functions of loadings of two packing media: Celite® Biocatalyst Carrier R-635 and Hat Creek Coal. As the research progressed, studies on the effect of nutrients addition to the coal column, observations of methanol degradations in the circulating liquid and the microorganism populations under a microscope, were added. RTD tests were performed on two identical biotrickling filter columns using CO2 tracer pulse test. Two baffle designs were chosen. RTD tests were done under dry bed conditions and over a range of air flowrates with 0 baffle, 1 baffle, and 2 baffles added into each column. Each run was replicated 6 times. The number of tank-in-series values (N), for each of the columns, were then calculated. The beds were acclimated with mixed culture from compost prior to the start of the methanol removal efficiency study. Nutrient solution and distilled water were circulated in the Celite® and coal columns, respectively. From the runs, which did not result in 100% conversion, the maximum EC values and rate constants of each column with different baffle configurations could be calculated. The inlet methanol concentration was randomly increased until poisoning occurred. Runs for the columns with 0 baffle were repeated with nutrients solution added in both columns. Samples from the liquid reservoirs were taken to study whether there was methanol degradation in the circulating liquid, and to study microorganisms under microscope. Results showed that addition of baffles decreased the N values of the columns and increased the backmixing in both systems. Maximum EC values, critical loadings, and poisoning limits were also increased with increasing backmixing. Coal was superior to Celite® as it gave good conversions without additional nutrients. Addition of nutrients in the coal column greatly improved its performance. La all runs, the rate of methanol removal was controlled by a zero order process. There was no significant methanol degradation in the circulating liquid Under the microscope, protozoa were found to be eating the biofilm. The presence of protozoa could help prevent bed from clogging.

Thesis/Dissertation

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2009-12-03

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http://hdl.handle.net/2429/16246

Chemical and Biological Engineering

University of British Columbia

UBCV

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