Selenium is an important ...

Selenium is an important element that is required for humans, animals, plants and other life forms. Selenium is naturally present in the Earth’s crust and its worldwide distribution has led to complex interactions between selenium and the natural environment (water, soil, sediments and air).

Two Process can be removed Selenium

1. R.O. and

2. Granular activated carbon (GAC) 

The typical pressure-driven membrane separation technologies consist of microfiltration, ultrafiltration, nanofiltration and reverse osmosis. Among these, only nano filtration and reverse osmosis are capable of separating selenium compounds from a contaminated wastewater stream. the use of nanofiltration was capable of selectively removing 95% of selenium from highly contaminated water. Solar powered ultrafiltration nanofiltration/reverse osmosis systems is capable of removing 74–94% of the initially present selenium concentrations. Further evidence of selenium removal by nanofiltration or reverse osmosis is, to say the least, very scarce in the reverse osmosis is listed as one of the best available technologies but that further industrial implementation of this technology is probably hindered by the fact that the solutions to be treated contain very dilute concentrations of solids, which is most often not the case for industrial wastewaters like acid mining wastewaters. Therefore, pre-treatment is required and reverse osmosis for selenium removal from polluted waste streams can only be used as a final polishing step, often described in the literature as a post-treatment step.as shown in the figure.

Granular activated carbon (GAC) is moderately effective in selenite  removal  from wastewater. Activated alumina is effective for selenite  removal . Slow sand filtration and the algal-bacterial process have recently been shown to be effective for the  removal  of  selenium  from agricultural drainage  water .