2019 Volume 10 Issue 2 Pages 71-83
To ensure the quality control of discharge water, we monitored the concentrations of volatile organic compounds (VOCs) weekly in wastewater discharged from buildings related to laboratories at six sub-campuses within the Kyoto University-Yoshida campus from December 2016 to December 2018. In general, the VOC levels in the wastewater were much lower than the VOC discharge standards of the city of Kyoto. Among the total of 1,817 measured samples, 12 samples exceeded the effluent standard of dichloromethane (DCM),accounting for 0.66%, and 1 sample exceeded the effluent standard of 1,4-dioxane, accounting for 0.06%. The highly accurate quantification with a low detection limit provided by the Environment Preservation Research Center of Kyoto University revealed a decreasing trend of DCM contamination from 2017 (0.0118 mg/L) to 2018 (0.0005 mg/L). The concentration of DCM in wastewater frequently exceeded the effluent standard in 2017 (11 samples), whereas only 1 sample exceeded it in 2018. The frequent violation in 2017 reflected the high demand of DCM in research activities and inappropriate handling of DCM liquid waste. Several investigations of the cause and alerts for prevention of recurrence had been conducted at the sites where the violations were detected. The integrated drainage management methods (IDMMs) at Kyoto University involve weekly monitoring of wastewater quality, providing information about wastewater analysis results, conducting investigations into violations and giving instructions to prevent recurrence, developing posters about the handling of organochlorine solvents, conducting surveys on the awareness of experimental wastewater management, and promoting training courses/workshops. The IDMMs and inspections of the facilities related to laboratory sinks and draft chambers,conducted by Kyoto University and the city of Kyoto in accordance with Revision of Water Pollution Prevention Law, are some of the key factors influencing the decrease in cases of violations and concentrations of DCM from 2017 to 2018.
