Researches on increasing the dissolved oxygen concentration in stationary waters Marilena Monica Boltinescu (Roza), Nicolae Vlad Sima, Dorina Nicoleta Albu, Mihaela Petroşel (Bănică) and Mihaela Constantin E3S Web Conf., 286 (2021) 01001 Published online: 12 July 2021 DOI: 10.1051/e3sconf/202128601001