Taiwan papilio

It's very hard to tell what it is by looking at the somewhat blurry photo at an angle. I expect that it is probably a very old memnon, as it doesn't appear to have the forewing androconia that a bianor male would have. The underside markings on old memnon males can turn orange with age. It could possibly be a beaten up old bianor female, but females don't normally drink industrial outflow and the suchlike.

Sorry I can't be definitive.
Adam.