Design and performance of an industrial scale biofilter for odorous gas treatment

Abstract

Odorous gas treatment is a challenging task due to the difficulties in identifying odor specific gases and their varied characteristics. A bio filter was designed for the treatment of waste gas stream from a tobacco leaf processing factory that discharged a high temperature gas stream from drying chambers with characteristics of tobacco odor. Major constituents of the foul smelling gas (gas flow rate of 1160 - 2100 rn'lr1) were identified and quantified using thin film micro sensors and was found to constitute mainly ammonia (60 - 80 ppm (v/v)) and hydrogen sulfide (80 -100 ppm (v/v)) after pre-treatment. A bio filter unit (11.65 m3 in volume) with a mixture of coconut fiber and compost as filter media was used to treat the odorous gases which eliminated the hydrogen sulfide completely while removing more than 80% of ammonia at the EBRT of 36 (s), producing a non odorous gas stream. The pH (6.5-7.5) and moisture (60 -65%) were kept at optimum levels to facilitate microbial growth and minimal pressure drops within the system. This paper details design, construction, operation, performance monitoring aspects involved in bio filtration in an industrial scale application and recommend many practical engineering solutions in its application.