They 'flushed' impurities from the system. = They 'flushed' impurities out of the system.
She published her first novel while still 'in the flush of' youth. [=while still young]
The committee succeeded in 'flushing out' [='finding'] several good candidates.
(..) Why would the task force release this photo to begin with? Get the word out, involve as many eyes as we can? Right. It's a good way to flush a guy out of hiding. Set off a bomb, get your picture taken. It got million people looking for the Winter soldier. (..)2016 Captain America: Civil War
(..) I get headaches, it's so bad. It's like, they just never go away, you know. The President should just clean up this whole mess here. He should flush it right down the f$cking toilet. I think I know what you mean, Travis. But it's not gonna be easy. - We'll have to make some radical changes. (..)1976 Taxi Driver
(..) The way you're pressing your thighs together under the table. The change in your breathing. And then your complexion. - My complexion? - You're flushed. - That could just be the wine. - Its the adrenaline. Say I did stay. What would happen? First, I would help you out of that little dress of yours. (..)2015 Fifty Shades of Grey