摘要：Among various petroleum-processing products, lubricating oil, cutting oil, etc. are finally disposed of as waste oils or oil containing effluents. Most of them are processed by simple burning. It occasionally cause some problems due to unlawful disposal occuring of bad odor, fire and so on. Since 1973 when the so-called “oil shock” happened, waste oils began to be appreciated as a source of energy being recycled as fuel oil because of a steep rise in price of petroleum-processing products. The authors reported previously on the actual status of the unlawful disposal and various properties of waste oils, which has been followed by additional investigations up to date. The unlawful disposal decreased markedly with the occasion of oil shock as a turning point, still being centered to disposal of bad waste oil though. On the other hand, waste recycling has been developed in the movement, showing efforts to recover the same as much as possible to be used as fuel oil instead of simple disposal by burning. Highly developed recycling of cutting oil as well as plain recycling of waste lubricant oil to fuel oil to be used by public bathhouses are executed in a good number of districts.
