The Bacteriology of Trickling Filters

Summary: The nature of the bacterial flora of trickling filters has been investigated. It consisted primarily of Gram-negative, rod shaped bacteria closely related to the flora of fresh water. These bacteria were able to grow on nutrient agar at 22° and belonged mainly to the genera Achromobacter, Alcaligenes, Flavobacterium, Pseudomonas and Zoogloea . The results failed to confirm the importance previously attributed to coli-aerogenes organisms, aerobic sporeformers and filamentous bacteria. The influence of homogenization on these findings is discussed. Further evaluation of the ecological importance of the various groups of bacteria was carried out by metabolic studies using synthetic sewage.