Peeponics doggy urine nutrient cycle system

Hi, I have a dog at home who uses a litter tray. It's basically a large plastic water run off tray with some AstroTurf. Currently, I have a pump that draws off liquids and deposits them into an empty soda bottle, which I flush down the toilet. But I was wondering if there is an easy way to convert the urine into nitrates which I could use in an aquaponics, or peeponics, system? Possibly using an attractive under water garden in a 25 gallon fish tank?