The full wastewater treatment train — preliminary, primary, secondary, and tertiary treatment — activated sludge process fundamentals and control variables, biosolids digestion and beneficial reuse, and the NPDES effluent standards every plant is held to.
Wastewater treatment removes pollutants in stages because no single process removes everything: screening and grit removal protect equipment, primary clarification removes settleable solids, secondary (biological) treatment removes dissolved and colloidal organic matter, and tertiary treatment polishes effluent further where discharge limits or reuse demand it. This module works through the activated sludge process in real operating detail — F/M ratio, solids retention time, RAS and WAS — plus biosolids digestion and dewatering, and the NPDES permit framework that sets the effluent limits a plant is legally required to meet.
By the end of this module you should be able to compute an activated sludge system's F/M ratio from basin volume, MLSS concentration, and BOD loading, and explain why that single number decides whether a plant's sludge settles well or bulks — a control problem the treatment-train fundamentals in Module 4 and the water quality standards in Module 12 both build on directly.