Black Streaks

Those are caused by the ablative white roof coating washing off during rain, etc. They're just a part of having an EDPM roof. You can clean the roof with blue Dawn or something much more expensive that's formulated for EDPM, but the coating will continue to do what it's supposed to do and more streaks will come. The more you clean the roof though, the more of that coating you'll wear off. Once you start seeing the black rubber membrane part that's under it, you'll have to get a new roof.