erm, many muslims here in Europe are refugees that we can't turn away and can't get rid off again because of international conventions. these people are usually also the most radical, isn't that just swell.
It would be a hugely difficult task to repatriate the populations that are in Europe right now.
However, if the problem were taken seriously enough, the EU and individual countries can definitely stop or reduce further inflows.
Strong border security, forced repatriation of illegals, all can be done, but it will take a much stronger will than seems probable with so many in Europe still enamored with multiculturalism.
The individual European countries have distinct national identities. They should each take a hardline approach toward integrating the immigrant populations they have let in.
This should include mandatory cultural classes, a mandate for language classes, strict prosecution of criminal actions, criminalization and an encouragement of reporting of abuses that stem from medieval sharia practices (ie clitorectomies, forced marriages, etc.) Even "take back the night" style street patrols and public shaming of those who indulge in sexual harassment would help raise awareness.
No one should expect these approaches will go smoothly. Many neighborhoods have transformed with unmanaged immigration into Islamic ghettos with rampant unemployment, no prospects for jobs or education, really not much different than you will find in slums in Cairo.
The Muslim immigrant population, legal and illegal, have decided that they want to be separate but equal, at least until they gain the upper hand through legal agitation for recognition of sharia and an unrestrained birth rate, so I would fully expect that integration will be very, very difficult.
You only have to watch the groveling of European apologists to get the sense that it will take a political sea-change to reverse the tide -
European Union apologizes for offense to Muslims