Degradation of Selenocyanate with an Advanced Reduction Process(ARP)

Selenocyanate (SeCN^(-)) is a common form of selenium contamination in refinery and mining wastewater generated from processing oil or minerals from seleniferous formations such as marine shales. Humans who drink water containing selenium over several years may experience hair or fingernail losses and numbness in fingers or toes. Recently, advanced reduction processes (ARP) that combine chemical reductants with activating methods has been studied to decompose contaminants that have the potential to be chemically reduced.

This paper focus on the application of ARP to selenium removal from wastewater containing selenocyanate. The ARP in this study consists of ferrous iron (chemical reductant) and UV light (activating method). During this research, control experiments were conducted to see the individual reactions of selenocyanate alone, selenocyanate with ferrous iron, and selenocyanate with UV light. Also, the effect of pH and UV light irradiance were studied.

The results show that the ferrous iron alone cannot improve selenocyanate removal. However, UV light is able to degrade selenocyanate, and the reaction rate increases as pH decreases. The ARP in this system (ferrous iron and UV) cannot improve the reaction rate from that of only UV light, but the addition of ferrous iron did decrease the final concentration of selenium at high pH.