Baking and Sterilizing Substrate

[iambecomedeath]

Hi everyone! It's time to deep clean my ball python's enclosure and do a substrate replacement. I am using Forest Floor Cypress Mulch by ZooMed that I bought at a local reptile store. I know a lot of people have talked about baking their substrate to sterilize it, especially when they buy it in person from a place that has reptiles. However, using an oven is not an option for me so I wanted to ask what else I can do? I don't have a deep freezer either, but I do have a grill. I am worried about how long it will take considering I have 3 different 24 quart bags. I know I likely will not need to use all of it (I have a 4' x 2' x 2' pvc enclosure) but I will need to use at least 2 of them if not another half bag.

Edit: I could try returning the substrate I have and maybe reorder from somewhere else online, but I am not sure if the shop is willing to take back the bags even if they are unopened.

Any advice is appreciated!