Fundamental research on the biological treatment of scrapped car's coolant and decomposition of nitrate, one of the main eutsrophic components, was carried out and the following results were obtained. It has become apparent that aqueous mixtures of ethylene glycol, a main component of the coolant and nitrate could be simultaneously decomposed. Decomposition rate of both components depended on the [TOC]/[TN] molar ratio and effective rate was attained at ca. two. When [TOC]/[TN] molar ratio was higher than two TN decomposed almost 100%, and lower than 2 TOC decomposed ca. 80%. On the basis of the results obtained, a recycle system was proposed using/fusing various technologies of developed for wastes.