Evaluation of nano-scale zero-valent iron for removal of organo-selenium species from industrial wastewater

硒是一种令人关注的污染物，存在于加拿大许多工业的工业废水中，包括煤炭开采，油砂开采，石油精炼和燃煤发电厂。在废水中，硒通常以无机形式存在，包括硒酸盐（SeO 4）2-和亚硒酸盐（SeO 3）2-含氧阴离子物质。应用于处理工业废水的生物处理方法已显示将无机硒含氧阴离子还原为元素硒。然而，在生物处理过程中，已经注意到形成有机硒化合物，例如具有较高毒性和生物累积倾向的硒代甲硫氨酸。最近的法规针对的是鱼组织中硒的生物累积量，而不是管道末端流出物中的硒浓度。有机硒的环境效应、毒性和严格的法规要求从工业废水中去除有机硒。Stantec热衷于开发一种技术，可以有效地从工业废水中去除有机硒，因为目前还没有针对这些化合物的技术。* 这项研究工作提出了评估使用纳米零价铁（nZVI）复合材料吸附去除工业废水中的有机硒物种。使用nZVI复合材料是有前途的，因为该材料已被证明具有从废水中去除各种无机金属和类金属的高潜力。nZVI吸附有机硒物种的能力将通过实验室批量和连续实验进行评估。将使用硒代蛋氨酸、硒代氰酸盐和S-（甲基）硒代胱氨酸作为有机硒化合物的参比品进行实验。将对这些参比化合物的吸附等温线和各种工艺参数（如废水pH值、离子强度、温度和其他竞争阴离子）的影响进行评价。在本项目下开发的这些新的理解将用于从工业废水中去除有机硒化合物。

Selenium is a contaminant of concern that is present in industrial wastewaters from many Canadian industries, including coal mining, oilsands mining, petroleum refining, and coal-fired powerplants. In wastewater, selenium is typically present in inorganic form which include selenate (SeO4)2- and selenite (SeO3)2- oxyanion species. Biological treatment processes applied to treat industrial wastewaters have shown to reduce inorganic selenium oxyanions to elemental selenium. However, formation of organic selenium compounds such as selenomethionine with higher toxicity and tendency to bioaccumulate have been noted during biological treatment. Recent regulations target magnitude of bioaccumulation of selenium in fish tissues rather than selenium concentrations in end-of-pipe effluents. The environmental effects, toxicity and stringent regulations demand removal of organoselenium species from industrial wastewater. Stantec is keen in developing a technology that will effectively remove organoselenium from industrial wastewaters as there are no technologies that has been demonstrated for these compounds. ****This research work proposes to evaluate removal of organoselenium species from industrial wastewaters by adsorption using nano zerovalent iron (nZVI) composites. Use of nZVI composites is promising as the material has demonstrated high potential for removal of wide range of inorganic metals and metalloids from wastewaters. The ability of nZVI to adsorb organoselenium species will be evaluated through laboratory batch and continuous experiments. Experiments will be conducted with selenomethionine, selenocyanate, and S-(methyl)selenocystine as references for organoselenium compounds. Adsorption isotherms and the effect of various process parameters such as wastewater pH, ionic strength, temperature and other competing anions will be evaluated for these reference compounds. These new understanding developed under this project will be employed for the removal of organoselenium compounds from industrial wastewaters.****************