Municipal wastewater treatment using a novel granular activated carbon based integrated fixed-film activated sludge sequencing batch reactor (IFAS-SBR)

Abstract

Integrated fixed-film activated sludge (IFAS) systems incorporate benefits provided by both attached and suspended growth systems. It is an advanced technology in wastewater treatment with high treatment efficiency and low capital and operational maintenance costs. This study used granular activated carbon (GAC) as a new carrier in plastic bio-ball carriers. Two laboratory integrated fixed-film activated sludge sequencing batch reactors (IFAS-SBR) – one with conventional plastic biofilm carriers (plastic-IFAS) and one with GAC encaged carriers (GAC-IFAS) – were operated for 120 days to treat synthetic municipal wastewater. Reactor treatment performance and biofilm formation mechanism were investigated in this paper. The GAC-IFAS sequencing batch reactor showed better and more stable performance compared to the plastic-IFAS sequencing batch reactor. GAC is a promising bio-carrier alternative due to its adsorption capacity and its porous structure, which provides a larger surface area for the biofilm growth. The results demonstrated that the concentration of attached biomass was 1.12 – 1.78 times higher than that of suspended flocs in GAC-IFAS sequencing batch reactor using HRTs of 12 h to 4 h. Moreover, adsorption and biodegradation could be achieved on the outer and inner layers of its surface concurrently. The assessment of adsorption kinetics was also performed by batch tests. Utilization of the newly developed GAC bio-carrier greatly improved the bioreactor performance for wastewater treatment.