Process Microbiology

The microorganism population in a trickling filter consists of aerobic, anaerobic, and facultative bacteria, fungi, algae, and protozoans. Also present are higher forms such as worms, insect larvae, and snails. The predominating microorganisms in the trickling filter are the facultative bacteria. Achromobacter, Flavobacterium, Pseudomonas, and Alcaligenes are among the bacterial species commonly associated with the trickling filter. Filamentous forms such as Sphaerolitus natans and Beggiatoa are found in the slime layer, while Nitrosomonas and Nitrobacter are present in the lower reaches of the filter.

Fungi in the filter are responsible for waste stabilization. Their presence becomes important in industrial wastewater treatment where pH levels are low. Various fungal species identified include Fusazium, Muco, Pencillium, Geotrichum, Sporatichum, and various yeasts. Fungi, however, are often responsible for clogging filters and preventing ventilation due to their rapid growth.

Algae are also found in trickling filters, albeit only in the upper reaches of the filter where sunlight is available. Their main role is not in degrading the organic matter but in providing oxygen during the daytime to the percolating wastewater. Some of the algae species commonly found in trickling filters include Phormidium, Chlorella, and Ulothrx. Algae can also clog the filter surface, resulting in undesirable odors.

Protozoans in trickling filters, as in activated-sludge processes, are responsible for keeping the bacterial population in check rather than for waste stabilization. The cil-iates are the predominating species among protozoa; they

0 0

Post a comment