Rapid Start-Up and Sustained Performance of Anaerobic Biofilm Reactors for Nitrogen Removal in Low C/N Wastewater: Characterization And Microbial Community Analysis of the Pd/A Process

Abstract

A Porous Polymer Gel Fillers (PPGF)-based partial-denitrification/anammox (PD/A) process in an anaerobic biofilm reactor was established, which started up in 79 days and removed nitrogen stably in low C/N wastewater. At the influent total nitrogen (TN) load of 130 ± 13 mg/L and the C/N ratio of 3, the effluent TN was 3 mg/L, reaching a removal efficiency of 98%. During the stable operation phase, the anammox activity reached 2.54 mg/L/h, contributing to 87% of TN removal. High-throughput sequencing showed that the relative abundance of anammox bacteria (AnAOB) on the biofilm reached 22% and contained four anammox bacterial genera. Phylogenetic analysis revealed that the dominant AnAOB were Candidatus_Jettenia species. Biofilm outperformed floc sludge in the nitrite accumulation capacity and the coordination between denitrifying bacteria and AnAOB. This study offers evidence for the rapid initiation of the mainstream anammox with common sludge for low-energy, high-efficiency nitrogen removal in low C/N wastewater.

Keywords: Partial-denitrification/Anammox (PD/A), Anaerobic Biofilm Reactor, nitrogen removal, rapid start-up, Low C/N Wastewater, Porous Polymer Gel Fillers (PPGF)