This means that your family was either bulgarian, because Calafat is exactly on the border- my family was born there.
However, the way it was spelled is wrong. I think they were trying to find a way to make it easier to be pronunced in English.
I believe it is Sergiev or Serghiev.
People were migrating back and forth on the DAnube river at that time because of the war in Balcans between Bugaria and Romania in 1916-1918.
So, probably your family is Bulgarian at origin.