INTENSIFICATION OF NITROGEN COMPOUND REMOVAL PROCESS FROM WASTE WATERS BY BIOFILTERS Статья Gogina E.S., Iantcen O.V., Ruzhitckaia O.A., Dabrovski V., Zhilka R., Boruzhko D. Water and Ecology. Vodoproekt-Giprokommunvodokanal.Sankt-Peterburg. Том 67. 2016. С. 35-45