A rockwool biofilter for the treatment of restaurant emissions

Sammanfattning: Over the past 20 years, the use of biological air pollution control has become a popular treatment alternative for contaminated gas streams. The objective of this licentiate thesis was to investigate the feasibility of a compact rockwool biofilter to treat emissions from a restaurant, to identify an appropriate microbial population for the inoculation of the biofilter, and suitable environmental conditions for this culture. Rockwool mats with pre-set structures were shown to have a good structural stability, developed low pressure drop, did not compact, and seemed to be a appropriate habitat for microorganisms. Bacteria from different environments were enriched in batch cultures; it was found that all cultures were able to oxidize rape-seed oil. Nutrients, mainly phosphorus and nitrogen, must be added occasionally to the bacterial culture. Clogging due to high depositions of grease could be prevented by using a mechanical collector installed upstream of the biofilter. The off-gas from the fryer consisted of a complex mixture of partially oxidized hydrocarbons and the short residence times (<10 s) provided in the filter were not sufficient to achieve a significant reduction of aldehydes or fatty acids.