I'm pretty sure that is an old coolant tank for a lathe grinder. I was thinking of a similar set up when I worked at a machine shop. It always struck me funny that no one set them up right and ceramic powder that was ground kept getting pushed through the pumps. It's nice to see someone with some good sense. Very nice design.
(Edited to add) On recycled water smell. Ozone generators keep the smell down. Water still smells funny, but it doesn't have that gag a maggot smell.
Welding class $1500, welder $300, gloves $20, hood $50, flux core $50, slag hammer $10, brush $5, metal $100+, cutting torch $250. Ability to make what you want, Priceless.