Abstract
This study aims to evaluate the toxic effect of influent and final effluent taken from a sewage treatment pilot plant, focusing on the effect of ammonia. Influent and final effluent were obtained in January and February from the pilot plant under little nitrification condition. The wastewater was examined based on the draft Japanese Whole Effluent Toxicity (WET) testing guidelines and a Toxicity Identification Evaluation (TIE) test using a green alga Pseudokirchneriella subcapitata. It was suggested that ammonia in the influent and final effluent, obtained in February, caused the toxic effect on P. subcapitata, although ammonia in those obtained in January seemed to do no toxic effect. It was also indicated that not only ammonia but also other chemicals like hydrophobic chemicals, oxidants and surfactants may cause the effect.
