INTRODUCTION

Automotive antifreeze is usually made from an ethylene glycol formulation. Such antifreeze can be re-refined to produce pure ethylene glycol, which can then be used to manufacture new antifreeze. Antifreeze has been "recycled" in many ways. The most pure ethylene glycol is obtained with a fractional distillation process, in which ethylene glycol is isolated and contaminants are removed. Many filtration systems do not achieve the purity specifications required by warranties of equipment manufacturers. Filtration system users must be certain that the use of the filtered material is allowable under warranty requirements and they should routinely obtain laboratory test results to ensure that they are within warranty tolerances.