Eleventh International Conference on The Constructed Environment

Abstract

The practice of discharging untreated wastewater to public water bodies is one of the factors damaging the aquatic ecosystem. Globally the estimate of untreated wastewater discharged is 80%. This problem becomes a concern in large cities where the population and economic activities are increasing. In many cities like Tokyo 80% of wastewater is collected by combined system and send to water reclamation center for treatment and reused. Reclaimed water has many potential uses for ecosystem restoration, but a need exists to better understand the impact of the application of reclaimed water into the aquatic ecosystem. The purpose of this study is to assess the potential impacts of discharge from two water reclamation centers located in Tokyo by whole effluent test method using Ceriodaphnia dubia as test species. The chemical analysis of nutrients, ion chromatography detection of anions and cation, heavy metal analysis, and several water quality index parameters was done to investigate the concentration of expected toxic substances. The whole effluent toxicity test shows that the sample taken from one of the reclamation center shows toxicity. Thus, it was recommended to use the whole effluent test along with the chemical analysis before discharging, move away from the combined wastewater collection system regardless of its cost and use natural ways such as phytoremediation for removing heavy metals, which might be the case for the observed toxicity.