Abstract
To estimate the interference action of chemicals, to the activated sludge, we established a method of measuring the toxicity (LC50) of these chemicals to the micro-organisms, using the oxygen absorption rate of this activated sludge as a parameter. Simultaneously, as a convinient method, we tried to acquire a toxicity value, using the mortality of protozoa as a parameter, and compared the results with the former.
We observed that the latter shows generally smaller values of LC50 (stronger toxicity). The above mentioned convinient method may be used to determine the rule of action in the case of an accident of the own sewage plant.
