Abstract
The purpose of this study is to develop a new method for treating wastewater containing diamines using yeasts. We isolated yeasts that could assimilate ethylendiamine (EDA) and hexamethylendiamine (HMDA) from approximately fifty yeasts stocked in the National Research Institute of Brewing that are mainly wastewater treatment yeasts. Consequently, three yeasts, Hansenula fabianii J640, Hansenula anomala J224-1, and Candida utilis IFO0626 were revealed to be able to grow well in culture containing EDA or HMDA as sole nitrogen source. In these yeasts, C. utilis IFO0626 showed the best removable ability, that is, it removed greater than 98% of 1,000 ppm EDA dichloride and HMDA dichloride in 48 h. The assimilation of 1 g of these diamine dichlorides needed approximately 10 g of glucose as a carbon source; therefore the ratio of C:N was calculated as 100:5. These yeasts were shown to prefer ammonium sulfate and urea to EDA and HMDA as nitrogen sources. It was shown that EDA or HMDA could be more effective decomposed by increasing the initial number of yeast cells in the treatment medium.
