These studies were concerned with the microbial ecology of trickling filters with particular reference to their possible application in the disposal of wastes from intensively housed pigs. As it is technically difficult to obtain satisfactory samples from full-scale filter beds an apparatus similar to that of Gloyna, Comstock & Renn (1952) was used. Perspex tubes (2 ft x 21/2 in) were rested on rollers rotating at 18 rev/min. The chassis was inclined (1:25) and the wastes applied to the raised ends of the tubes. Increase in weight was used as an index of the rate and extent of development of microbial film on the tubes and Chemical Oxygen Demand as an index of their efficiency of purification of wastes. When irrigated with domestic sewage the performance of the experimental filters was comparable with that reported in the literature for plastic-packed filters irrigated at comparable rates. Irrigation with piggery wastes, either neat or diluted, tended to inhibit purification and/or cause the film to slough. It was concluded that trickling filters were unlikely to be suitable for purification of wastes from intensively housed pigs unless the concentration of organic matter was reduced by dilution or prior treatment such as anaerobic digestion. The microflora of films irrigated with domestic sewage was dominated by Acinetobacter and yellow-pigmented non-motile Gram-negative rod-shaped organisms. Irrigation with piggery wastes yielded a film consisting of Acinetobacter only. It was deduced that purification in certain aerobic waste treatment processes may be dependant upon the association of these two organisms. There is evidence from the literature to suggest that Pseudomonas may be dominant in other situations. The nature of the waste and the operational procedures of the plant apparently having a selective influence on the microbial association which becomes dominant in any particular waste treatment process.
|Date of Award||1972|