Efficacy of a novel biofilter in hatchery sanitation: I. Removal of airborne bacteria, dust and endotoxin

A novel biofi lter containing organic, bentonite and halloysite media was applied for elimination of microbial pollutants from the air of an industrial hatchery. The concentrations of total mesophilic bacteria, Gram-negative bacteria, thermophilic actinomycetes, dust and bacterial endotoxin were determined in the air of hatchery during 2 months before installation of the biofi lter, and during 6 months after installation of the biofi lter, at the inlet and outlet ducts from each medium. Before installation of the biofi lter, the concentrations of total mesophilic bacteria, Gram-negative bacteria, thermophilic actinomycetes, dust and endotoxin in the air were within the ranges of 0.97- 131.2 × 103 cfu/m3, 0.0-34.4 × 103 cfu/m3, 0.0-0.02 × 103 cfu/m3, 0.37-4.53 mg/m3, and 50.9-520,450.4 ng/m3, respectively. Enterococcus faecalis and Gram-negative bacteria (Acinetobacter spp., Escherichia coli, Enterobacter cloacae, and other species) prevailed among bacterial species recovered from the air of the hatchery. A total of 56 species or genera of bacteria were identifi ed in the air samples taken in the examined hatchery; of these, 11, 11 and 6 species or genera respectively were reported as having allergenic, immunotoxic and/or infectious properties The concentrations of total mesophilic bacteria, Gram-negative bacteria, Enterococcus faecalis and endotoxin found at the inlet duct of the biofi lter after its installation were signifi cantly smaller compared to those recorded before its installation (p<0.05). The concentrations of Gram-negative bacteria, Enterococcus faecalis and dust found at the outlet ducts of biofi lter after its installation were signifi cantly smaller compared to those recorded at the inlet duct of the biofi lter (p<0.01). The concentrations of total meso-philic bacteria were also smaller at the outlet ducts of the biofi lter compared to that at the inlet duct; however, the difference was not signifi cant because of the massive growth of Streptomyces species in the biofi lter’s media which contaminated the outcoming air. In conclusion, the applied biofi lter proved to be effective in the elimination of potentially pathogenic bacteria, dust and endotoxin from the air of the hatchery. The effi cacy of the biofi lter could be improved by the inhibition of the Streptomyces growth in the media of the biofi lter.