With the limited information you have given (the floor size and type would be nice, along with the nature of the soiling) it sounds like you need a scrubber/drier possibly a sweeper/scrubber/drier.
Challenger are OK along with Nilfisk, Tennant, Wetrok, Numatic and a multitude of others.
Why don't you have a chat with Mike at Express Cleaning Supplies (they sponsor this forum).
I always find that taking a rep from your equipment supplier to site for their advice is worthwhile - they will have a greater level of expertise and may be able to take a machine there for you to trial before you make that financial plunge.