@ Donkey,
Oslo Airport in Norway runs a similar system - aircraft go to the de-icing area just off the threshold of the runway to maximise the holdover time. All the fluid then drains into a holding tank, where it is filtered and then reused. when you consider the airport charge you for this fluid, and then re-use it for someone else, they must be making a mint.
Mind you, it is far cheaper for an operator than the consequences of a crash - the manchester air disaster in the 60's (date?) was caused by icing. At that time, the consequences of aircraft icing was not really understood.