I don't know where did you take the info but look at this:
Dubai World Central International Airport, the airport will have an annual cargo capacity of 12 million tons, more than three times that of Memphis International Airport, today's largest cargo hub, and a passenger capacity of more than 120 million - almost 30% more than
Hartsfield-Jackson Atlanta International Airport, currently the world's busiest passenger airport.
Designed for the future, Dubai World Central International Airport proposes to handle all next-generation aircraft, including the A380 super-jumbo. Up to four aircraft will be able to land simultaneously, 24 hours a day, minimising in-air queuing.
Hartsfield-Jackson Atlanta International Airport held its ranking as the world's busiest airport in 2007, both in terms of passengers and number of flights, by accommodating 89.4 million passengers and 994,346 flights respectively.