14.2 Aerobic processes for BOD removal 14.2.1 Microflora of aerobic processes Examples of bacteria often reported from investigations on the microflora of aerobic waste water treatment Organisms Comment Achromobacter Common water and soil bacteria Acinetobacter Utilised for phosphorous removal Alcaligenes Common water and soil bacteria.Important denitrifyer Bacillus Producer of extracellular hydrolytic enzymes Beggiatoa Filamentous bacteria stimulated by high sulphur content Corynebacterium Common water and soil bacteria Escherichia coli Introduced from faeces,together with other enteric bacteria,but not considered important in the process. Flavobacterium Common water and soil bacteria Methanogenic bacteria Obligately anaerobic methane producing bacteria.See Chapter 14.1 Microthrix Filamentous bacteria stimulated by low sludge load and high fatty acid content.May cause sludge bulking. Nitrobacter Obligate aerobe and litoautotroph which oxidises NO2-to NO3- Nitrosomonas Obligate aerobe and litoautotroph which oxidises NH3 to NO2- Nocardia Filamentous actinomycete associated with foaming in the activated sludge process Pseudomonas Important denitrifyer.Utilise a wide spectrum of carbon sources. Sphaerotilus natans Filamentous bacteria that can cause bulking of the sludge. zoogloea ramigera Producer of extracellular polysaccharides. Utilises a wide spectrum of carbon sources Believed to be important for flocculation and biofilm formation14.2.1 Microflora of aerobic processes 14.2 Aerobic processes for BOD removal