An uncle of mine has a sawmill/wood moldings factory. They ran into some regulatory problems when they tried recycling water. They recycled so many times tha

An uncle of mine has a sawmill/wood moldings factory. They ran into some regulatory problems when they tried recycling water. They recycled so many times that evaporation losses concentrated the copper and lead in the city water until it became too high to discharge. They were not adding any new metals, just concentrating what was already there as far as they could tell. They had to start consuming more water to dilute the process water back below discharge limits. Last I heard they were looking into some kind of ION exchange to capture the heavy metals, but the economics were not good. I assume a Chip fab does not have a bunch of leaky steam pipes so they have less evaporation losses, but they probably have more regulated chemicals in their used wash water.