Immobilized Cell Augmented Activated Sludge Process for Enhanced Nitrogen Removal from Wastewater

Abstract

The immobilized cell augmented activated sludge (ICAAS) system combines a cell immobilization technique and an offline enricher‐reactor for the bioaugmentation of the activated sludge system to improve treatment performances. In this study, enhanced nitrogen removal using ICAAS was investigated. Laboratory‐scale, offline, batch enricher‐reactors were used to maintain nitrification and denitrification activities of coimmobilized nitrifiers and denitrifiers used to augment a laboratory‐scale completely mixed activated sludge system (CMAS) treating synthetic wastewater. Cellulose triacetate was the media used to entrap nitrifiers and denitrifiers at a 2:1 mass ratio. The ICAAS augmented with the coimmobilized cells between 5 and 20% by volume gained 24 ± 5% higher nitrogen removal than a control CMAS, which provided nitrogen removal of 28 ± 7%. The ICAAS scheme is a viable alternative for upgrading existing activated sludge systems to gain better nitrogen removal.