A method of recycling spent ethylene or propylene glycol recovered from aircraft de-icing solutions containing glycol, water and other substances to produce substantially virgin glycol, said method comprising, in combination, the steps of: i) recovering spent glycol from the de-icing facilities of airports and storing same in storage means, ii) removing spent glycol having a predetermined low % purity concentration from spent glycol stored in said storage means to produce a working spent glycol and storing said working spent glycol in one or more storage tanks (22,23), iii) filtering said working spent glycol from said one or more storage tanks (22,23) through at least two filtering stages (28,31) to substantially remove all solids in said other substances followed by an evaporation step (33,33') wherein said working spent glycol is heated to a temperature sufficient to evaporate only water to bring said working spent glycol to a glycol concentration of about 50% purity for storage in a buffer tank, iv) adjusting the pH of said glycol concentration of about 50% in an agitator tank to adjust the pH to a desired value and then carbon filtering said glycol concentration of about 5%, v) feeding a predetermined volume of said carbon filtered glycol concentration of about 50% in an evaporator section of a distillation tower operating under vacuum, vi) heating said batch at a predetermined temperature to evaporate said glycol concentration of about 50% in a continuous stream of vapors, vii) sensing the temperature of said stream of vapors in a hot packing section of a chimney section spaced above said distillation section to monitor the actual temperature of said stream of steam and feeding temperature signals representative thereof to a computer controller, viii) cooling said stream of vapors after it exits said chimney section to condense said stream of vapors into a condensed liquid, ix) monitoring on a continuous basis (a) said temperature signals to correlate same with the evaporation temperature of water and glycol, and (b) glycol concentration signals form a refractometer located in a conduit through which flows said condensed liquid, to recover from said condensed liquid, water, water mixed with glycol below a concentration of 99.5%, and substantially virgin glycol having a concentration of at least 99.5%, and x) directing said substantially virgin glycol from its associated reservoir for further testing and certification of the purity thereof and storing same in certified holding tanks for use by aircraft de-icing vehicles. i) recovering spent glycol from the de-icing facilities of airports and storing same in storage means, ii) removing spent glycol having a predetermined low % purity concentration from spent glycol stored in said storage means to produce a working spent glycol and storing said working spent glycol in one or more storage tanks (22,23), iii) filtering said working spent glycol from said one or more storage tanks (22,23) through at least two filtering stages (28,31) to substantially remove all solids in said other substances followed by an evaporation step (33,33') wherein said working spent glycol is heated to a temperature sufficient to evaporate only water to bring said working spent glycol to a glycol concentration of about 50% purity for storage in a buffer tank, iv) adjusting the pH of said glycol concentration of about 50% in an agitator tank to adjust the pH to a desired value and then carbon filtering said glycol concentration of about 5%, v) feeding a predetermined volume of said carbon filtered glycol concentration of about 50% in an evaporator section of a distillation tower operating under vacuum, vi) heating said batch at a predetermined temperature to evaporate said glycol concentration of about 50% in a continuous stream of vapors, vii) sensing the temperature of said stream of vapors in a hot packing section of a chimney section spaced above said distillation section to monitor the actual temperature of said stream of steam and feeding temperature signals representative thereof to a computer controller, viii) cooling said stream of vapors after it exits said chimney section to condense said stream of vapors into a condensed liquid, ix) monitoring on a continuous basis (a) said temperature signals to correlate same with the evaporation temperature of water and glycol, and (b) glycol concentration signals form a refractometer located in a conduit through which flows said condensed liquid, to recover from said condensed liquid, water, water mixed with glycol below a concentration of 99.5%, and substantially virgin glycol having a concentration of at least 99.5%, and x) directing said substantially virgin glycol from its associated reservoir for further testing and certification of the purity thereof and storing same in certified holding tanks for use by aircraft de-icing vehicles.