Removal of Toxicity, COD, and Fe from a Metal-Working Facility UF Permeate

Abstract

A metal-working facility employs two ultrafiltration (UF) membrane systems to treat spent metal working fluids and oily waste from sumps and other nonpoint sources. The facility is regulated for oil/grease, toxicity and Fe. Chemical-oxygen demand (COD) will be added in future permits. Also, the facility’s domestic wastewater treatment plant is aging, requiring replacement. Short-term treatment solutions were developed for toxicity and total Fe. A long-term approach for addressing Fe, toxicity, and COD and treatment of the facility’s domestic wastewater in a single bioprocess was also investigated. In the short term, granular activated carbon (GAC) columns were selected to remove toxicity and an aeration/pH adjustment/settling process was selected for Fe. Toxicity, COD, and Fe were removed successfully in a biological sequencing batch reactor (SBR) process, and a packaged conventional wastewater treatment plant will most likely be the chosen long-term solution. Depending on the discharge COD limit, an activated carbon polishing step may be needed prior to discharge.