Pilot Scale Demonstration of an Activated Iron Process for Removing Heavy Metals and Nutrients from the FGD Wastewater

摘要

A novel chemical treatment technique has been invented for removing heavy metals and nutrients for hard treated FGD wastewater. This integrated treatment system employs new understandings of iron chemistry to create a highly reactive mixture of iron minerals for chemical transformation and mineralization of various heavy metals in water. A pilot test, which was demonstrated at a Southern Company's power plant, consistently reduced total mercury (Hg) from around 100 ug/L to ＜ 0.005 ug/L. Total selenium (Se), of which most is selenate, was reduced from approximately 3,000 ug/L to ＜ 10 ug/L. In addition, other heavy metals, such as arsenic (As), cadmium (Cd), chromium (Cr), nickle (Ni), lead (Pb), zinc (Zn), and copper (Cu) were all reduced to single ppb levels. Nitrate is removed by over 99% consistently. The process uses inexpensive iron based chemicals and produces a limited amount of non-hazardous solid waste. The iron powder consumption is estimated to be 300 - 400 tons for treating 500 gpm of FGD wastewater.