Biodegradation of high acrylamide concentrations in integrated fixed film activated sludge (IFAS) wastewater treatment system

Abstract

The study was to evaluate the capacity of IFAS technology to enhance the acrylamide (AM) biodegradation in the biological wastewater treatment systems at high concentrations of 200, 300, 400, and 800 mg AM/L. Two sequencing batch reactor (SBR) systems operating as the IFAS and conventional activated sludge (AS) were operated at the solids retention time (SRT) of 9.0 days and hydraulic retention time (HRT) of 24 h at the operating temperature of about 28 °C. The experimental results revealed that the mixed culture bacteria in the IFAS system biodegraded acrylamide at the removal efficiencies of 64.9, 82.4, 99.5, and 86.3% while the AS system removed 36.4, 75.1, 71.8 and 55.9% at the acrylamide concentrations of 200, 300, 400, and 800 mg AM/L, respectively. As acrylamide concentrations increased in the wastewater, the sludge productions decreased due to the acrylamide toxicity, but the biodegradation rates increased resulting from less complexity of mixed substrates. Ammonia was stripped out due to relative high temperature and pH; therefore, the ammonia inhibition effects on the acrylamide biodegradation were not found. Due to the media clogging, the diffusion of substrates was limited; therefore, biodegradation rates in the IFAS system were remarkably less than the AS system. It can be concluded that the IFAS was superior to the AS system because of additional fixed film biomass.