Summary:

Predicting the effect of toxic substances on living organisms is extremely difficult since this is effected by the complex environmental situation. Even substances having a direct and immediate effect cannot be directly detected but have to be interpreted by the reaction of the organism effected. It is generally accepted that the effect of toxic substances on respiration rate of bacteria when monitoring waste water is a useful indicatior especially becasue of the rapid response. However factors such as changing substrate and biological adaptation need to be accounted for. Experience within the chemical industry of the use of such on-line Toxicity monitors is described, in particular in conjunction with automatic divert to a balancing tank.