Removal of Selenium from Wastewater using ZVI and Hybrid ZVI/Iron Oxide Process
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Selenium (Se), often in form of selenocyanate (SeCN-), which present in some of refinery process wastewater known as stripped sour water. As Se discharge is increasingly regulated, the industry struggles to find a cost-effective technology for SeCN- treatment. Zero-valent iron (ZVI) technology, with some successes in remediating toxic-metal contaminated groundwater remediation, emerges as a potential solution for addressing SeCN- problem. In this study, bench scale tests were conducted to investigate the removal of SeCN- from wastewater with ZVI. The removal efficiency was evaluated by a series of tests under different conditions such as initial pH, various ions, ZVI particle size, dissolved oxygen (DO) and iron oxide. Results showed that SeCN- was effectively removed from wastewater with ZVI and Fe(II) filings when the water pH was controlled at approximately 6 with sufficient DO. The further evaluate of treating SeCN- using hybrid zero valet iron (hZVI) system has also been conducted in this study. The hZVI system process is a novel chemical treatment that has shown valuable potential for removing several heavy metals from wastewater. This study concluded that at bench scale, the removal efficiency of SeCN- in the wastewater is over 99% with 2-steps of hZVI reactors and a HRT of 12 hours. In essence, this study concluded that ZVI is a highly valuable potential cost-effective treatment for SeCN- removal from wastewater and the results from bench scale hZVI system can be effectively used to scale up the system to serve the industrial needs in the future.
Yang, Zhen (2012). Removal of Selenium from Wastewater using ZVI and Hybrid ZVI/Iron Oxide Process. Master's thesis, Texas A & M University. Available electronically from