The Microbial Associations Developing on Experimental Trickling Filters Irrigated with Domestic Sewage

S ummary . The bacterial flora of the film which developed on experimental trickling filters irrigated with domestic sewage was dominated by Acinetobacter and yellow-pigmented Gram negative rod-shaped organisms and it was deduced that purification in certain aerobic waste treatment processes may depend upon an association of these 2 organisms. Further evaluation of the operational procedures likely to have a selective influence on the microbial association which becomes dominant was made in studies using synthetic sewage.