Help with Cleaning Aluminum Bleachers?

Looking for some input on the best way to clean Aluminum bleachers. A local dirt racetrack has requested our services to clean the grandstands and we have never done anything like this before. We are pretty well established with the residential cleaning in the area but this is something new for us and was wondering if anyone out there has ever ventured into this area. The surfaces are very dusty with mold/mildew present on one side. Any help on cleaning methods, chemicals, etc would be appreciated.