Too hard to say with no more info than was given.It sounds like the mold has developed in to mycelium. If so will hepa vacuuming be enough to remove the hyphae that has grown into the food source?
Is this a finished basement with sheetrock walls, carpet and furniture?
Like I said.Too hard to say with no more info than was given.
I assumed there was no visible growth and assumed concrete walls. ??? Depending on the situation it could need a good pressure washing or could need more aggressive wiping of the walls. If as you mention you have microbial growth that has taken root then removal and or sanding could come into play. ???
Not enough information to really be of much more help.