Startup strategy for nitrogen removal via nitrite in a BAF system

Simultaneous nitrogen and carbon removal in a single biological aerated filter by the bioaugmentation with heterotrophic-aerobic nitrogen removal bacteria

ABSTRACTAgrobacterium sp. LAD9 capable of heterotrophic-aerobic nitrogen removal was applied into a single biological aerated filter (BAF) for bioaugmented treatment of municipal wastewater. The achievement of simultaneous nitrogen and carbon removal in the bioaugmented system was systematically evaluated by ratios of COD to nitrogen (COD/N), ranging from 1 to 20. The results showed that at an appropriate COD/N ratio of 10, the BAF exhibited excellent carbon and nutrients removal, the averaged removal efficiencies for COD, NH₄⁺-N and TN were 92.3%, 100% and 80.0%, respectively. Long-term operation of the bioaugmented system also confirmed the stability of the treatment efficiency. Further comparisons of SOUR and PCR-DGGE profiles between the bioaugmented and the control system revealed that the introduction of strain LAD9 greatly changed the structure of original microbial community and facilitated their capabilities of aerobic nutrients removal. The proposed bioaugmentation strategy is of particular importance to upgrading or retrofitting concurrent municipal wastewater treatment systems.

Multi-omics analysis reveals structure and function of biofilm microbial communities in a pre-denitrification biofilter

The highly complex microbial communities in biofilm play crucial roles in the pollutant removal performance of wastewater treatment plants (WWTPs). In the present study, using multi-omics analysis, we studied microbial structure, key enzymes, functional traits, and key metabolic pathways of pre-denitrification biofilter in an urban WWTP in China. The analysis results of metagenomic and metaproteomic showed that Betaproteobacteria and Flavobacteriia were dominant in biofilms. The integrated metagenomic and metaproteomic data showed that the expression of nitrogen metabolism genes was high, and the high proportion of denitrification module indicating that denitrification was the main nitrogen removal pathway. The most abundant denitrifying bacterial genera were: Dechloromonas, Acidovorax, Bosea, Polaromonas, and Chryseobacterium. And microorganisms with denitrification potential may not be able to denitrify in the actual operation of the filter. The integrated analysis of metaproteomic and metabolomic showed that there was a correlation between biofilm microorganisms and metabolites. Metabolomic analysis indicated that metabolic profiles of biofilms varied with layer height. This study provides the first detailed microbial communities and metabolic profiles in a full-scale pre-denitrification biofilter and clarifies the mechanism of denitrification.