Biggs, at just 13, is a qualifier for the 400m individual medley and Ruback for the 1500m freestyle.
There are more than 1000 entries for championships, including 25m world champion Lauren Boyle and fellow London Olympians Matt Stanley, Glenn Snyders, Melissa Ingram, Dylan Dunlop-Barrett, Tash Hind, Gareth Kean and Samantha Lucie-Smith. There are record entries from AWD swimmers, including London Paralympic gold medallists Sophie Pascoe, Mary Fisher and Cameron Leslie.
Heats are from 10am each day and finals from 6.30pm.
To qualify for the world championships, swimmers will need to equal or better the Fina A standard.
Meanwhile, qualification for the junior world championships is equalling or bettering the Fina B standard.