2017 Volume 8 Issue 3 Pages 149-154
Hiroshima University Higashi-Hiroshima campus is one of the few universities with large-scale water recycling system and a general experimental drainage, the latter referring to washings from laboratory ware used in experiments. These liquid wastes are purified at the Environmental Research and Management Center and the recycled water is used for flushing toilets in the restrooms of the campus. To properly maintain the water quality of the recycled water, it was very necessary to store experimental liquid wastes in designated tanks, including toxic substances and not to pour them into the general experimental drainage. However, many tap aspirators were still being used for the purpose of solvent evaporation, and the solvent contaminated the general experimental drainage. Thus, in order to prevent the treatment and water recycling plant of the general experimental drainage in Hiroshima University from being contaminated with volatile organic compounds, the tap aspirators were changed into a diaphragm pump. All tap aspirators could not be changed, but the effect of preferentially changing to pumps which are frequently used, was verified from a monitoring result of 14 years from FY2003 to FY 2016 of the volatile organic compound concentrations in the general experimental drainage and the treated water. Before changing into the diaphragm pump, the concentrations of benzene, chloroform, and dichloromethane in the influent water were 1.2 - 459.0μg/L, 0.2 - 3128.0μg/L, and 0.1 - 4131.3μg/L, respectively, and these concentrations drastically decreased from FY2010 until FY 2013, when the change has been completed. Before changing into the diaphragm pump, the concentrations in the treated water were at most 7.7μg/L, 137.8μ/L, and 212.3μg/L,respectively, and decreased to <0.1μg/L, 18.0μg/L, and 11.0μg/L, respectively, after the change, showing that the outflow prevention for chemicals conducted in Hiroshima University was effective.