The price an airline pays for its fuel is a closely-guarded secret.
It's negotiated with the fuel suppliers on a basis of the amount required per month or per quarter. I guess at Brussels most airlines pay US$0.80-0.90 per U S gallon.
fftopic:
Did you hear that Delta Air Lines flight DL067, Boeing 767-300ER (N174DN) en route from Zurich to Atlanta was forced to dump fuel over the Med on January 19th, 2005 before diverting to Nice Airport following a fuel leak.