College of Engineering and Technology

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Browsing College of Engineering and Technology by Author "Anderson, William A."

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    Estimation of Nitrogen Requirement in Peat and Perlite Biofilters Removing Hexane from Air
    (Springer Netherlands, 2001) Kibazohi, Oscar; Anderson, William A.; Moo-Young, M.
    Biofiltration experiments to remove hexane from air were conducted in column reactors packed with peat, perlite and their mixture. The particle size of the solid medium ranged from 1.70 to 4.75 mm, and the average empty bed superficial velocity was 20 m/h. To achieve and maintain a high rate of hexane removal, addition of nutrient solution was necessary. Adding a nutrient solution of a commercial fertilizer containing 1000 g of nitrogen for the first two weeks, followed by a weekly addition of 280 g of nitrogen per m3 of filter bed was found to be effective in maintaining a high hexane removal rate between 20 and 30 g/m3.h. The hexane removal rate decreased gradually to less than 15 g/m3.h in 50 days due to an accumulation of biomass in the reactors. Pressure drop, which varied depending on the type of packing, also increased drastically to maximum values of 120 Pa/m for 100% perlite and 2930 Pa/m for the mixture. For long-term operation and low energy cost, prevention of biomass accumulation and maintenance of low pressure drop is essential. When the frequency of nutrients addition was reduced excessive biomass growth, and increase in pressure drop with time were controlled. Our observations showed that addition of a nitrogen source of approximately 1 kg of nitrogen per m3 of filter bed for the first and second weeks, and every 30 days (approximately) resulted in an extended life and slightly lower hexane removal. The columns packed with peat and the mixture showed a better hexane removal than the column packed with perlite alone. However, the column packed with perlite had the lowest pressure drop.
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    Removal of Hexane in Biofilters Packed with Perlite and a Peat–Perlite Mixture
    (Kluwer Academic Publishers-Plenum Publishers, 2004-06) Kibazohi, Oscar; Yun, Soon-Il; Anderson, William A.
    Removal of hexane from air–hexane mixtures in biofilters packed with different solid media under nitrogen supplementation was performed for 70 days. Two columns containing Perlite or a mixture of peat and Perlite, were used. The solid media were supplemented with nitrogen source up to 1 kg/m3 per week for high nutrient supplementation and 0.2 kg/m3 per month for low nutrient supplementation. A high rate of hexane removal: 95 g/m3 h was achieved under high nutrient supplementation, high air flow rate and high hexane concentration. However, the percentage of hexane removal decreased with increasing air flow rate and hexane inlet concentration. For high nutrient supplementation the type of solid medium did not significantly affect the biodegradation capacity. With low nutrient supplementation, the highest removal rate was achieved in the column containing the peat–perlite mixture. The column containing perlite had a significantly lower pressure drop (20 Pa/m) than the 2400–2930 Pa/m observed for the column containing the mixture. Perlite offers an opportunity of running a biofiltration process at a lower and stable pressure drop if the nutrient supplementation is managed properly.