A MICROBIOLOGICAL SURVEY OF 10 ACTIVATED-SLUDGE PLANTS

The activated sludge process is an aerobic biological method for organ ic matter reduction from waste water. The objective of this research w as to conduct a survey of micro-organisms present in 10 activated slud ge plants. The following groups of organisms were investigated; eubact eria, filamentous bacteria, fungi, yeasts, algae and protozoa. Eubacte ria, fungi and yeasts were isolated on casitone glycerol yeast extract agar, rose bengal chloramphenicol agar and yeast malt extract agar re spectively. Twenty-two different genera of eubacteria were isolated an d identified as mainly gram-positive rods belonging to the genus Bacil lus. Spore-forming bacteria predominated over non-spore formers. Micro thrix parvicella was the most common filamentous organism detected in the activated sludge plants studied. When compared to the rest of the microflora, fungi and yeasts were not detected in large magnitude, mos tly belonging to common genera. Algal types detected were the common f resh-water and polluted water algae. Protozoans were well represented with the most common types being Paramecium and Euplotes spp.