Recent development in Activated Sludge Process (ASP)

Abstract

Activated sludge process is the oldest technology used in the biological treatment of wastewater. A series of modification took place in the activated sludge process because of higher efficiency at lower cost. Step aeration, tapered aeration, complete-mix, oxidation ditch, contact stabilization, high-purity oxygen, were the initial modifications of ASP. These modifications did not become much popular because of certain problems. Current trends are the combinations of other technologies with ASP. The other technologies compensate the limitations of the Activated Sludge Process. Such developments are Membrane Bio-Reactor (MBR), Powdered Activated Carbon Treatment (PACT) system, IFAS (Integrated Fixed Film/Activated Sludge Systems). MBR use membrane in ASP, which avoid sludge bulking and allow system to cope up with high BOD. PACT system use powdered activated carbon in ASP. Powdered activated carbon adsorbs nonbiodegradable compounds that are present in wastewater. IFAS use both suspended growth and attached growth. Addition of media in ASP causes higher amount of biomass in the aeration tank allowing for enhanced treatment and/or increased loading rates. These three technologies are much efficient in degradation of wastewater. Use of these technologies have lesser burden on tertiary treatment.