Our engineering department was recently required to hire a university graduate due to /ahem/ reasons. Best not to ask why. We have been put into a difficult situation with this person, and I would like to ask for ideas on how to make the best of it.

This person has several problems at play, including knowledge and skills gaps, but overall I have come to believe that this person has never had to take anything seriously before in his life. The cause of this may be the /ahem/ reason mentioned above. To be clear, the issues do not include antisocial behaviour or rudeness - not at all. The person is pleasant enough to talk to, but only insofar as you would talk to a drinking buddy. As soon as you try to talk business, out comes the disrespect. You are often interrupted by their opinion. Offer them a correction, you endure an explanation why they thought they were right in the first place. Explain a method, you get an explanation of another one that doesn't work. I often quote Luke Skywalker "Every word of what you just said is wrong".

A few sample quotes:
"Why don't you just weld the door shut?" [when asked to draw a figure showing a door handle removal procedure]
"But that will take me all day!" [when asked to convert a batch of drawings from one CAD format to another]
"What is this?" [holding a rivet, the most common fastener in the aerospace industry]
"I just specified glue on all surfaces to make sure that it would stick" [on the inside and outside of the hose]

I could go on, but some of you may believe me less and less, the more I write. Since this guy cannot competently do anything, every task requires more hours of supervision than it would take for the supervisor to do it himself. At this point 4 people have tried to step into the supervision role (including myself) and we have all emerged in disbelief. We even have an intern who is trying. I hear them argue, too.

This is becoming a distraction and a burden for many people in the department. I would say I am proud of my engineering team, except for this person. We have some other newly hired people, who are shining, I must add. The intern I mentioned is awesome, but dealing with this person may discourage him from coming back to my company after he graduates. Any on-the-job training activities for the new (permanent) hires will include him by default. The effectiveness of their training is being reduced by his interference. I was planning several more training sessions but postponed them, to the detriment of the other new people.

Are there any suggestions on how to deal with this? How to reduce the pain? How to maintain encouragement and support for the other new hires?
Please remember that the appropriate solution is not possible.