Selenium deficiency refers to not having enough selenium in your system. Symptoms may include fatigue, muscle weakness, and infertility, among others.

Selenium – a mineral found in many foods – could reverse the cognitive impact of stroke and boost learning and memory in aging brains, according to University of Queensland research.

You need only trace amounts of selenium to survive. Falling outside of this narrow therapeutic window can have significant health consequences.

Removing selenium from water is challenging because it's so water soluble, Giammar said. Iron electrocoagulation is up to the challenge by generating iron-containing solids with large surface areas.