Bacterial composition of activated sludge: identification and visualization

Summary

The objective of this work is to describe the capabilities of a method for visualizing activated sludge bacteria based on the information from an Internet resource for developing textbooks and/or manuals. Advanced methods of microscopy of the bacterial community are considered: optical light, scanning electron (SEM), transmission electron (TEM), confocal (CLSM), fluorescence hybridization in situ (FISH), new generation sequencing (NGS). On the basis of the methods presented, examples of bacterial flocculation of activated sludge with extracellular and reserve biopolymers are given. According to the highest citation frequency in professional reference books and literature, a sample of the most typical bacteria from the composition of floccules of activated sludge was compiled. Examples of visualization of four bacteria by SEM, TEM, KLSM, FISH methods are given: Bacillus subtilis (gram-positive, spore-forming, optionally aerobic), Nitrospira defluvii (gram-negative, aerobic, chemolithotrophic, nitrite-oxidizing), Candidatus «Accumulibacter phosphatis» (gram-negative, phosphate-accumulating), Candidatus «Microthrix parvicella» (gram-positive, filamentous, actinomycete). To date, the Internet resource contains a sufficient amount of reliable data on the visualization of activated sludge bacteria, their functionality and properties related to the key processes of biological treatment, classification or taxonomy, as well as on the methods of their microscopic study. The implementation of the capabilities for identifying the bacterial composition of activated sludge and the quantitative ratio of heterotrophic, autotrophic and phosphate-accumulating biomasses provides for setting and/or calibrating models of ASM series (for example, in GPS-X, BioWin, etc. software environment).

Key words

biological treatment , activated sludge , phosphate accumulating bacteria , filamentous bacteria , bacterial composition , extracellular biopolymers , visualization , identification , filamentous bacteria , autotrophic bacteria