I generally totally reject the "eye for an eye" mentality when dealing with criminals but I believe bullying is one offense where it is totally appropriate. Bullies should have the absolute shit beaten out of them. Don't cause any permanent physical harm to them, just batter, bruise and humiliate them. Repeat as necessary until learning takes place. If it doesn't, throw them in jail along with the other violent offenders.
I'm not a violent person by any means, but in cases like this were vulnerable people are singles out like this i think nothing less than taking them round the back and having seven bells kicked out of them and then have them walk in that other persons shoes suffering they same degradation they thought was perfectly acceptable to pile on others would go some way to serving some form of justice.
Not a perfect solution and it wont right the wrong but its about the best i can think of as some form of punishment for their actions.

I love how these essentially read "I'm not a violent person....BUT I WANT TO SEE ME SOME PEOPLE BEATEN UP!!!"
I'm going to be blunt here, but I apologise for any offense: As someone who came within an inch of suicide himself due to the physical and psychological abuse he suffered, I must say I'm quite disgusted at the idea of inflicting it on others. Violence, humiliation and inflicting pain are not "justice". The desire to inflict abuse on these people is NO DIFFERENT from their desire to inflict it on their co-worker, except people try to "justify" it by saying "ah, it's okay, I can indulge in brutality and abuse here, because these people aren't very nice". Well, they didn't like her either, did they? If you're using your dislike for them as an excuse to indulge in the desire to create the "outsider" who is then attacked, it's the same thing, hiding behind ideas of "justice". And those ideas fail, as I see
Locutus of Bored has already articulated in the post above
Again, I'm sorry but I must be blunt. Someone who is opposed to abuse and assault is OPPOSED TO ABUSE AND ASSAULT. There can be no exceptions. Saying "...apart from on these people because they're criminals/not very nice" is no different from "apart from these people because they're the wrong religion/race/tribe/political group". It's the same instinct: find an outsider and viciously attack them in order to boost your own esteem and sense of social solidarity.
In this case, the sense of societal cohesion has been threatened, so people respond, as is instinctive, by finding someone to blame, and ruthlessly attacking them as a rallying point for everyone to reaffirm their commitment to shared ideals. And once the labeled outsider is broken and bloody and humiliated, everyone feels better.
As
LoB pointed out, it's circular, as plenty of abused and bullied people go on to do it to others in order to reclaim their broken self-esteem. It's a tragic cycle that I personally want nothing to do with.
I hope I have not offended anyone; I can get a bit intense at times, as I'm sure you're aware.