Waste Water Filtration?
I'm seeing the challenge of pressure washing a gas station because you can't dump anything into the sewer without getting permission/permit, and some times testing is required. So I was wondering if there is any portable filtration systems that cleans everything out of the water so you don't have to dump anything? I have seen the filters on ultimate washer.com but you still have to dump the clean* water every day [recommended], and again they don't filter out the soap so it would become more concentrated as you reuse it.
I might have to have something custom built.