The review looked at ways to clean up soil contaminated with heavy metals. They found that using certain plants and micro-organisms, known as bio-phytoremediation, was effective. Vetiver grass was the most successful plant at removing heavy metals from the soil. Combining plants and micro-organisms worked even better and was faster at cleaning up the polluted soil. Adding organic manure to the soil also helped to remove more heavy metals and reduce the amount taken up by plants.