White Paper: Removal Of Metals From Metal Finishing Wastewater Using a Granular, Magnesium-based Adsorbent
by Matthew D. Walter, Joseph T. Witkowski, and Aileen Reyes
This paper details a granular, Magnesium-based Adsorbent which has been used to remove various metals from surface finishing wastewater streams. The metals treated in this study include copper, nickel, and zinc. Effluent concentrations of the treated metals are typically less than 0.5 mg/L.
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Environmental regulations have become increasingly severe regarding the types and amounts of pollutants that may be released into the environment. In particular, metal finishers are commonly restricted to the metal concentrations and pH of waste water that may be discharged into natural waterways, municipal sewers, etc. Various treatments have been utilized to remove metal ions from water while rendering the pH suitable for discharge. The most widely used method for treating waste water streams is chemical precipitation. Using this method, the pH of the stream is raised with an alkali (e. g. Mg(OH)2, NaOH, Lime, etc.) until the metals precipitate as the insoluble hydroxides. Often, chemical precipitation is not completely successful in reducing metal concentrations in the waste water stream to comply with discharge regulations. Additional treatment techniques such as reverse osmosis, ion exchange, and activated carbon are often necessary to reduce the metal concentration sufficiently for discharge. The adsorbent described herein is a novel Magnesium-based adsorbent from Martin Marietta Magnesia Specialties, LLC that has been shown to remove heavy metal ions from mildly acidic to mildly alkaline surface finishing waste water while simultaneously neutralizing the acidic components of the waste. Three case studies are presented detailing the performance of this granular medium as well as information about how this granular, Magnesium-based product removes metals from solution.
Click here to download the entire White Paper in pdf format.