The landlord and tenant may want to check out the remarkable research on toxic mold removal done by environmental expert Dr Ed Close. Simply diffusing a therapeutic-grade essential oil regularly will likely result in an environment very hostile to mold.
http://www.secretofthieves.com/mold.cfm/79544

It seems like it would make traditional remediation projects easier and more effective, as well as creating a healthier environment in which to work and tenants to live.

In one instance, 10,667 stachybotrys mold spores were identified in a per cubic meter area. After diffusing Thieves essential oil for forty-eight hours, Dr Close retested. Only thirteen stachybotrys remained. Similarly, 75,000 stachybotrys mold spores were identified in a sample of sheetrock. After seventy-two hours of diffusing, no stachybotrys mold spores remained.(Stachybotrys has a reputation for being the most toxic mold.)