Abstract
Isolation, stock, and in addition, monoxenic and mass culture of specific species of aquatic oligochaetes, Nais sp., Aeolosoma hemprichi, Pristina sp. and Dero sp. were attemped successfully. Small aquatic oligochaetes are the typical metazoa found frequently in the activated sludge and bio-film from domestic sewage treatment plant operated by low BOD loading. Using a sterilized activated sludge as the metazoan food, the monoxenic growth rate of small aquatic oligochaetes, the effects of temperature, pH, phosphate buffer solution concentration, organic concentration, share stress, food concentration and sort of bacteria as food, on the growth rate were measured. The optimum temperature of cultivation for A. hemprichi, Nais sp. and Pristina sp. were 33, 25 and 30°C, respectively. Phosphate buffer concentration which could grow normally were 1/375M for A. hemprichi and Nais sp., 1/150M for Pristina sp. and 1/7,500M for Dero sp. The optimum pH values in cultivating the oligochaetes ranged from 6 to 8. The growth of Nais sp. could not be observed in much stronger share stress.
Specific growth rates (μ) ranged from 0.35 to 0.43 day-1 for A. hemprichi and 0.10 to 0.13 day-1 for Nais sp., respectively when the sludge concentration was more than 500 mg · l-1.
