The Mountain Empire Community College ‘Water and Wastewater Distance Learning Course’ makes available all its documentation on the web. This section describes secondary treatment systems, including trickling filters, rotating biological contactors, activated sludge, operation and control, stabilization ponds, aerated lagoons and intermittent sand filters.
MECC (n.y): Course ENV149: Wastewater Treatment Plant Operation: Lesson 10: Secondary Treatment. (= Mountain Empire Community College. Water and Wastewater Distance Learning ). Big Stone Gap: Mountain Empire Community College (MECC) URL [Accessed: 18.03.2010]