I flush it down the loo! Goes down fine so far.
I also have the lovely covered corner cat tray, so that combined with the cat's best means you would never know we had a tray, most people who come are surprised when they realise what it is. Does make it a bit of a mission though taking the tray to the bathroom, lid off, sifting through, flushing, lid back on, back to its corner. Sigh, the perils of being a slave.
How one 5 month old kitten can pee and poo so much in 24 hours is beyond me.