Microalgae-assisted fixed-film activated sludge MFC for landfill leachate treatment and energy recovery

Abstract

The sustainability and innovation of a novel leachate treatment technology is a matter of vital significance. Bio-electrochemical-driven wastewater and leachate treatment methods, particularly MFC, and their improvements have attracted scientists’ attention recently. This study developed a new MFC system, which consisted of an anodic chamber, a cathode chamber with fixed biofilm carriers and a low-cost sheet of carbon felt between them as a membrane-like separator. The study was conducted to evaluate the capacity of MFC coupled with integrated fixed-film activated sludge (IFAS), to enhance the efficiency of the treatment and the amount of energy produced. Three MFC systems with different cathode processes were compared, namely, conventional activated sludge (MFC-AS), MFC-IFAS, and microalgae coupled MFC-IFAS (MFC-IFAS/MA). The experimental results revealed that MFC-IFAS/MA produced higher power density and nitrogen removal than the other two systems. The average removals of COD, NH4+-N, and total nitrogen (TN) were, 69.9%, 84.2% and 60.5% for MFC-AS, 84.3%, 79.2% and 71.6% for MFC-IFAS; and 82.0%, 90.3% and 88.6% for MFC-IFAS/MA. MFC-IFAS/MA demonstrated its superior electrochemical behaviors and nitrogen removal and this behavior was referring to the dual effect of fixed-biofilm and microalgae assimilation. This study investigated for the first time the symbiosis between microalgae and IFAS in an MFC reactor, which may open a new prospect for MFC application.