Australia's Science Forum

Could anyone tell me how they treat/deal with/dispose of waste potassium nitrate solution?
It is an oxidiser so really shouldn't be heated to recrystallise, and shouldn't be ground in case it sparks ?

Thanks

The CSIS tells us its a number 16. Disposal: waste solutions of this chemical may be disposed of down the sink (To Sewer) Page 206 taken from CSIS.