Mold is always connected with moisture problems. Moisture problems can occur in areas where rainfall is heavy and drainage is insufficient. Mold can grow on many kinds of surfaces including drywall, tile, fabrics and even concrete. On concrete basement floors, a problem with moisture rising up from the wet ground can cause a fuzzy, white mold to grow on the surface. Molds can cause health problems including allergies, asthma, infections and other respiratory reactions. Mold should be removed as soon as you see it, and preventive measures should be put into place to avoid it.
Scrub the surface with a stiff-bristled brush and a solution of 1/2 cup of laundry detergent to 1 gallon of water. For areas with more stubborn mold, the University of Missouri Extension recommends scrubbing the moldy surface with a solution of 1/2 to 1 cup of chlorine bleach in 1 gallon of water. Keep the area well ventilated until the solution dries. Remove all excess water with a wet/dry vacuum.
Scrub area with a trisodium phosphate (TSP) solution if any mold remains. To make the solution, dissolve 1 cup of TSP in 2 gallons of warm water.
Dry the moisture out by heating the area thoroughly with a space heater until all surface moisture dissipates.
Build up soil around the foundation so that rainfall runs away from the house. Add French drains around the foundation if heavy rainfall is a continuous problem. According to the website Ask the Builder, a French drain can help divert rainwater away from the house, which helps keep basement concrete surfaces drier. These are simple underground plastic pipes that are perforated and surrounded with gravel to help move water away from the house.
Seal cracks on the walls of the basement and around the foundation with a waterproof cement sealer available at your local home improvement store.
Paint cement walls and floor with a cement paint, using two coats.
Keep the concrete area where the fuzzy, white mold occurred well ventilated to prevent regrowth, and run a dehumidifier weekly to keep moisture from building up in the area.