Zeolite packed biologically active filter (biofilter) to reduce odorous emissions from a confined swine building

Abstract

A zeolite packed biofilter was retrofitted to a confined swine feeding operation in Eastern Washington, and evaluated for its ability to reduce the malodors from fan exhaust drawn from an internal under-slat manure storage pit. Ammonia (NH₃) was used as the representative constituent of swine waste malodor due to its readily detectable exhaust air concentrations greater than 3 parts per million. Twenty-four pre-filter samples and twenty-four post-filter samples of NH₃, collected over a 10- month period using colorimetric gas detector tubes, revealed the zeolite biofilter reduced NH₃ by an average of 90%. Nitrite assays and Polymer Chain Reaction (PCR) analysis confirmed that active populations of the nitrifying bacteria Nitrosomonas were able to attach and grow on the surface of the zeolite. Using cotton swatch absorption method and an odor panel it was found that the zeolite biofilter improved malodors from swine barn exhaust in 70% of the trials.