In February 2020, the California State Water Resources Control Board announced revised drinking water Response Levels for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in drinking water. The new Response Levels (RLs) were set at 10 parts per trillion (ppt) for PFOA and 40 ppt for PFOS. The previous RL was 70 ppt for a combined total concentration for the two contaminants.

A Midwest manufacturer of automotive parts was experiencing elevated levels of zinc in the effluent from their existing conventional wastewater treatment system. This wastewater was generated through a multi-stage cleaning and zinc phosphate process which produced elevated levels of both particulate and dissolved zinc in the wastewaters.