Don't "sterilize" anything. There will be many resilient microorganisms surviving which are just waiting to take over anything when they have the chance to.

You should add some beneficial microorganisms, often sold as mycorrhizae, and take a look at living soil. A few worms or critters here and there are also great!

Soil should regulate itself, but you can give it a small headstart.

Regularly add some compost or dead plant parts, symbiotic plants, and so on.

If you don't like dirt, as I see it a bit in your "keeping everything clean" mentality, maybe come over to [email protected].

I tried hydro this season, and I was so amazed that most of my stuff next year will be grown hydroponically!

You probably don't have to toss it. I'd try sterilization first, and if it happens again, you'll know that the soil can't be reused. You can sterilize it by baking it in the oven at 180°F for 30 minutes or leaving it in a clear plastic bag in the sun for a few weeks.