Simultaneous partial nitrification, endogenous and autotrophic denitrification in a single-stage electrolysis-integrated sequencing batch biofilm reactor (E-SBBR) for stable and enhanced kitchen digested wastewater treatment.

Abstract

Listen

Translate article

Simultaneous partial nitrification-denitrification (SPND) is a promising process for nitrogen (N) removal from kitchen digested wastewater characterized by a low C/N ratio. However, its widespread application is often restricted due to the unstable partial nitrification and unsatisfactory denitrification performance. This work developed a novel simultaneous partial nitrification, endogenous and autotrophic denitrification process using a single-stage electrolysis-integrated sequencing batch biofilm reactor (E-SBBR) with anoxic/electro-anaerobic/aerobic operating strategy. The novel process considerably enhanced the stability and N removal efficiency (NH4+-N>94.5% and TN>90.8%) of the SPND process. The pre-electro-anaerobic phase achieved alkalinity and H2 generation, and intracellular carbon storage. The increased alkalinity resulted in increased free ammonia (FA) which secured complete suppression of nitrite-oxidizing bacteria (NOB). SPND efficiency in the aerobic phase was dramatically improved using polyhydroxyalkanoates (PHAs) and H2 as electron donors for endogenous and autotrophic denitrification. Microbial community analysis indicated the successful washout of NOB and the enrichment of ammonia-oxidizing bacteria (AOB), denitrifying glycogen accumulating organisms (DGAOs), autotrophic and heterotrophic denitrifiers in the system. This research presents a distinctive SPND process for intensified kitchen digested wastewater treatment and gives insights into the underlying mechanism.