| The introduction of Whole Effluent Toxicity (WET) testing has been considered for the management of chemicals in Japan. Although sewage water is one of the main effluent, there is little knowledge of the biological effect of sewage water in Japan. Fundamental information on the presence or absence of the biological effect, decrease in the effect by sewage treatment works and chemicals affecting aquatic organisms in sewage water is required. This study aimed to evaluate a biological effect of influent and final effluent from a sewage treatment pilot plant and to seek biologically affecting chemicals in sewage water. Influent and final effluent were obtained twice and tested based on the draft Japanese WET testing guidelines using green alga Pseudokirchneriella subcapitata. Both of the influent and final effluent exhibited some growth-inhibiting effects in the first and second tests, but the final effluent was less effective than the influent. The results revealed the improvement of a biological effect of sewage water by an activated sludge treatment. Toxicity Identification Evaluation (TIE) suggested that biologically affecting chemicals were ammonia, hydrophobic and non-polar chemicals, and oxides or surfactants for the influent, and ammonia and oxides or surfactants for the final effluent. |
