Mitigation of multiple air emissions from swine buildings using corn cob biofilters

摘要

Biofilter media selection and moisture content fluctuations significantly influence biofilter performance. Media with significant amounts of small particles have higher static pressure drops which lowers airflow through the biofilter. Inadequate moisture can reduce biological activity and decrease filter efficiency. Too much moisture (following a watering or rainfall event) can plug media pores, restrict airflow through the media, produce anaerobic pockets and generate nitrous oxide (N2O). In this study, a naturally occurring adsorbent (diatomaceous shale) was tested to manage media moisture content. Also, corn cobs were tested as an alternative biofilter media because wood chips are expected to be less available in near future due to emerging emerald ash borer disease. Five lmxlmxlm biofilter cells were built to treat air from pit fan exhausts of a swine finishing bam. One biofilter cell was filled with wood chips and one was filled with corn cobs. Three other biofilters were filled with corn cobsmixed with 5, 10 and 15% (by volume) diatomaceous shale, respectively. Results showed that all of the biofilters were effective reducing H2S and NH3 emissions without generating N_2O. The corn cobs were less dense and more porous than the wood chips andhad lower pressure drop values. Adding 15% diatomaceous shale to the cobs helped manage media moisture and improved H_2S and NH3 reduction efficiencies.