Two-step nitrification in a pure moving bed biofilm reactor-membrane bioreactor for wastewater treatment: nitrifying and denitrifying microbial populations and kinetic modeling

Abstract

The moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) is a novel solution to conventional activated sludge processes and membrane bioreactors. In this study, a pure MBBR-MBR was studied. The pure MBBR-MBR mainly had attached biomass. The bioreactor operated with a hydraulic retention time (HRT) of 9.5 h. The kinetic parameters for heterotrophic and autotrophic biomasses, mainly nitrite-oxidizing bacteria (NOB), were evaluated. The analysis of the bacterial community structure of the ammonium-oxidizing bacteria (AOB), NOB, and denitrifying bacteria (DeNB) from the pure MBBR-MBR was carried out by means of pyrosequencing to detect and quantify the contribution of the nitrifying and denitrifying bacteria in the total bacterial community. The relative abundance of AOB, NOB, and DeNB were 5, 1, and 3%, respectively, in the mixed liquor suspended solids (MLSS), and these percentages were 18, 5, and 2%, respectively, in the biofilm density (BD) attached to carriers. The pure MBBR-MBR had a high efficiency of total nitrogen (TN) removal of 71.81±16.04%, which could reside in the different bacterial assemblages in the fixed biofilm on the carriers. In this regard, the kinetic parameters for autotrophic biomass had values of YA=2.3465 mg O2 mg N(-1), μm, A=0.7169 h(-1), and KNH=2.0748 mg NL(-1).

Impact of dissolved oxygen and loading rate on NH3 oxidation and N2 production mechanisms in activated sludge treatment of sewage

“…High‐throughput sequencing was used to quantify the AOB, NOB and anaerobic AOB of the MAS system at two loading rates (Table S1) following previously described protocols (Leyva‐Diaz et al ., 2015a,b; Szabo et al ., 2017). As observed in the conventional A/O control system (Zhang et al ., 2018), Nitrosomonas also appeared to be the predominant AOB genus in all sludge samples from the MAS system at the two loading rates (Table S1).…”

“…4), the mean AOB and NOB abundances in the MAS system at the two loading rates amounted to 0.07–0.69% and 0.22–0.26%, respectively, whereas no anaerobic AOB were detected owing to their low abundance. These values were similar to previously reported results of 0.12–1.00% for AOB and 1.00–2.00% for NOB in biofilm or membrane biological systems, respectively (Leyva‐Diaz et al ., 2015a,b), and an extremely low anaerobic AOB population that was detected in a microaerobic BNR system (Fitzgerald et al ., 2015). As observed in the conventional A/O control system (Zhang et al ., 2018), compared with that of AOB, the contribution of anaerobic AOB to NH 3 oxidization in the MAS system at the two loading rates appeared to be negligible, which was possibly because of the organic matter in the sewage.…”

Nitrogen removal performance and microorganism community of an A/O-MBBR system under extreme hydraulic retention time

“…The A/O-MBBR system achieved NH 4 + -N rate of 98.4% under HRT of 9 h and DO concentration higher than 2.0 mg/L [18]. Moreover, TN removal rate achieved around 72% in an MBBR-MBR process at HRT of 9.5 h [19]. Moreover, DO concentration of 5.4 mg/L was another reason for improving nitrification performance in the R O , although the NH 4 + -N removal rate was still lower than the previous study.…”

Biofouling Formation and Bacterial Community Structure in Hybrid Moving Bed Biofilm Reactor-Membrane Bioreactors: Influence of Salinity Concentration

“…Compared to the activated sludge process, the MBBR-MBR offers the development of fixed biofilm over the media placed within the bioreactor, which increases the sludge retention time of the biomass, promotes the development of more specialized microbial communities, and increases the total solids' concentration in the system without increasing the mixed liquor suspended solids. This leads to more economic treatment of wastewater [10,11]. Additionally, the placement of a downstream MBR after the MBBR process offers a very high-quality effluence due to membrane filtration, which also removes the majority of pathogens.…”