Capacity Enhancement of Enterobacter aerogenes for Heterotrophic Nitrification in Integrated Fixed Film Activated Sludge (IFAS) Wastewater Treatment Process

Abstract

Enterobacter aerogenes was found recently as a high capacity bacterium for degrading acrylamide (AM) in the culture media.  The AM biodegradation was inhibited by free ammonia nitrogen due to the failure of heterotrophic nitrification in the sequencing batch reactor (SBR) wastewater treatment system.  In this study, the heterotrophic nitrification of E. aerogenes was enhanced with IFAS technology using BioPortz moving media operated at the solids retention time (SRT) of 9 days and temperature of about 28 ^oC.  The experiments were conducted comparatively in the conventional activated sludge (AS) and IFAS systems containing either mixed culture bacteria or E. aerogenes for autotrophic and heterotrophic nitrifications, respectively.  The results revealed that E. aerogenes could be enhanced with IFAS technology to complete heterotrophic nitrification.  There was no significant difference in nitrification between AS and IFAS systems of two microbes if the systems were properly operated.  Ammonia stripping was found in the AS systems whenever nitrification was failed and CO₂ was stripped out, resulting in the increase of pH.  The clogging of BioPortz media with calcium carbonate precipitates reducing the IFAS performances was firstly reported as a result of operating the IFAS systems at the relative high temperature and moderate hardness.