Control of Chromium Hexavalent (Cr -VI) Pollution on Waste Water in Nickel Ore Extraction Industry with Phytoremediation TechnologyErikha Maurizka Mayzarah, Setyo Sarwanto Moersidik and Lana SariaE3S Web Conf., 68 (2018) 03011DOI: https://doi.org/10.1051/e3sconf/20186803011