That is quite dissimilar from an actively aerated compost tea, except that if you were going use that run-off for any purpose you should do so ASAP; don't let it be stagnant for hours. Using it in an outdoor garden or houseplant is fine, but that alone might not be enough to sustain many plants...
You have to understand that if you have reasonable amounts of humus and other extremely small particles which carry electrical charges, they happen to be able to 'absorb' an overwhelming majority of the cations in the solution. That would include the likes of ammonium (NH4+), potassium (K+), magnesium (Mg++), iron (Fe+), calcium (Ca++), and also sodium (Na+) . Chances are that the run-off would seriously lack these ions, and instead contain primarily anions like nitrate nitrogen (NO3-), phosphate (PO4-), sulfate (So4-) and Cl- if those were present in the fertigation solution or soil in the first place. Those kind of nutrients have a tendency to flush right out of the soil, even outdoors when it rains outside.