ECOSYSTEM-LEVEL WET TEST OF CAFETERIA DRAINAGE USING MICROCOSM SYSTEM

Abstract

In Japan, the introduction of the WET (Whole Effluent Toxicity) test is under processing in consideration, but this test may be different from the actual ecosystem phenomena because it is a single species test in spite of the natural ecosystem consists of multi species biota. In this study, we developed the WET test using microcosm (M-WET) which is a simulated ecosystem model and consisted of several species of producer, consumer and decomposer. Both the number of organisms as structural parameter and DO as functional parameter after cafeteria drainage addition were analyzed by branched-type ANOVA, and the microcosm no observed effect concentration (m-NOEC) and toxicity unit (TU) were calculated. As result, the m-NOEC of cafeteria drainage was calculated as 5% and the TU was as 10, and assessed that the cafeteria drainage was discharged safely. It is important to assess the complex influences of chemical agents, such as surfactants, medicines and so on, to the environment. To conduct such comprehensive assessments, M-WET tests should be used to examine drainage with collecting total toxicity test data through single-species tests of chemical contaminants in environmental water.