Reduction potential of microbial, odour and ammonia emissions from a pig facility by biofilters

The intention of this study was the determination of the potential to reduc e specific microbial bio-aerosol (cultivable bacteria and fungi, total cell counts of microbes, airborne endotoxins and microbial volatile organic com pounds, MVOC), odour and ammonia emissions from a pig facility by biofilter s. Five identical biofilter units in half technical scale were filled with different filter materials (Biochips, coconut-pear, wood-bark, pellets+bark and compost) and connected in parallel to a piggery. The results showed ob vious differences between the filter materials. Numbers of airborne cultiva ble bacteria were decreased by ca. 70 to 95 % and the total counts of bacte rial cells from ca. 25 to (>) 90 %. The total amount of fungal cells was re duced by at least 60 %, although the percentage of cultivable moulds in the air after passing the filters was sometimes higher than before. Airborne e ndotoxins and MVOC were effectively reduced by all filter materials to at l east 90%. Regarding odour, the average reduction was between 40 and 83 %, w hereas only one of the filters proved to be capable of slightly reducing th e ammonia emissions. No relationships between odour/ ammonia and microbial bioaerosols with regard to the reduction efficiency of the different filter materials or the total load of the emitted air could be established. A ten dency could be shown, that biofilters best capable to reduce odour emitted slightly more airborne bacteria, both cultivable and total cell counts.