Adsorption purification of waste water from chromium by ferrite manganese Liliia Frolova, Mykola Kharytonov, Iryna Klimkina, Oleksandr Kovrov and Andrii Koveria E3S Web Conf., 168 (2020) 00026 Published online: 06 May 2020 DOI: 10.1051/e3sconf/202016800026