Abstract: Aeolosma hemprichii is one of the highest animal species in active sludge.Taking advantage of their predatory function may probably offer a new method to treat the surplus sludge.However,their existence in active sludge with a considerable quantity has been believed occa-sionally and uncontrollable.In this investigation,the emergence of aeolosma hemprichii was occasional yet if no inoculation.But if it was inoculated,the quantity of the worms was controllable by adjusting DO,pH etc.