Mathematical modeling on the nitrogen removal inside the membrane-aerated biofilm dominated by ammonia-oxidizing archaea (AOA): Effects of temperature, aeration pressure and COD/N ratio
Introduction
For the conventional biological nitrogen removal (BNR) in the biofilm, nitrite oxidizing bacteria (NOB) outcompetes heterotrophic bacteria (HB) for the nitrite, increasing the consumption of oxygen in the nitrification and carbonaceous substance in the denitrification. The nitrogen removal via the nitrite-pathway, comparatively, exhibits lower resource consumption and higher removal efficiency [1]. For mainstream during the municipal wastewater treatment, autotrophic nitrogen removal, combining the partial nitrification and anaerobic ammonia oxidization (ANAMMOX), is more effective, which excludes the supplement for carbon source and reduces 60% for oxygen demand [2], [3]. HB growth, however, is identified on the soluble microbial product (SMP) and decay released substrate from the ANAMMOX bacteria metabolism [4], [5], not even during the advanced treatment of wastewater with organic substance in low amount, impacting the systematic performance. Hence it’s practical to incorporate the HB in the wastewater treatment for enhancement of carbonaceous substance removal. Simultaneous nitrification and denitrification (SND) is feasible to be effectively implemented to achieve the high-efficient removal of nitrogenous and carbonaceous substances during the BNR. Furthermore, short-cut pathway, viz. the partial nitrification and the denitrification via nitrite, would improve the nitrogen removal by reducing the oxygen demand during the controlled nitrite oxidation and the consumption of organic matter for the subsequent denitrification process [6].
Characterized by the biofilm attached on the gas-permeable membrane, membrane-aerated biofilm (MAB) presents great technological advantages on the high-efficient removal of organic and nitrogen substances [7]. It’s been widely demonstrated that controllable nitrogen removal inside the counter-diffusional biofilm system exhibits higher total nitrogen (TN) removal efficiency and lower energy consumption than the conventional nitrification–denitrification process within the co-diffusional biofilm. Counter-diffusion of electron donors and electron acceptors inside the MAB [8] promote the formation of redox-stratified of metabolic processes [9], [10], [11]. Then the SND process is feasible within the distinct microbial niche [12], [13], particularly the short-cut pathway via nitrite through well-regulating oxygen surface loading, based on the aeration pressure in the membrane lumen [14] and the air flowrate. In essence, nitrite accumulation is involved in the aforementioned partial nitrification/nitritation process, generally realized by the physiological distinctions between ammonia and nitrite oxidizing microbes. Investigations reported that multiple operational factors, including the oxygen [15], temperature [16], pH/alkalinity [17], salinity [18] and free ammonium and nitrous acid [19], [20], [21], are extensively utilized to regulate the growth competition between the nitrifiers [22]. The denitrifying microbes are mainly categorized to the facultative anaerobes, with diversified metabolic patterns, which are insensitive under most of the above conditions. Slow-growing ammonia-oxidizing bacteria (AOB), however, are susceptible to the implemented parameter ranges, particularly inhibited by the low oxygen and ammonium availability and the temperature stress.
It’s been investigated that, under certain extreme environmental habitats, as the high temperature and salinity [23], low ammonium [24] and oxygen, ammonia-oxidizing archaea (AOA) is more active than AOB [25], [26], [27], which might depend on the lower biokinetic parameters of AOA compared with AOB, including the affinity constants for ammonium [28] and oxygen [29]. Consequently, AOA is more competitive than AOB under low ammonium [30] and oxygen [31] for the partial nitrification as indicated in the autotrophic nitrogen removal system [32], [33]. It might be feasible and effective to include AOA as an alternative to AOB-mediating BNR system [32], [33], [34]; few researches, however, have been conducted on the relevant heterotrophic biofilm system to elucidate the possible mechanism and identify regulatory measures for the practical application.
Performance dynamics could be explicitly comprehended through the microbial interactions for the complicated BNR systems. Generally, it’s time-consuming and effort-demanding [35] to conduct and stabilize the BNR system based on experimental evaluation of operational parameters. Over the years, mathematical modeling of wastewater treatment process, particularly the BNR process, has been extensively conducted and proposed as an important tool to comprehensively interpret the complex aquatic system, predict systematic performance and improve the design and optimization of high-efficient BNR process for the practical application after evaluating the impacts of different practical strategies on the emerging techniques.[35], [36], [37], [38], [39], [40], [41], [42], [43], [44] Though incompletely reflecting the actual system, the modeling results could be conducive to evaluating the experimental process and outlining the feasibility research on the critical aspects of the process [45].
For counter- and/or co-diffusional biofilms, several models are available for the autotrophic nitrogen removal via nitritation dominated by AOB and/or AOA and the subsequent ANAMMOX [34], which might be affected by the presentence of HB growing on the biomass decay products [5] or SMP and decay released substrate from the metabolism of the ANAMMOX bacteria [4]. As mentioned above, it might be practical to include the HB within the BNR process, indicating the relative-significance of necessitating SND process for the heterotrophic biological systems during the wastewater treatment irrespective of the presence of organics. Based on one-dimensional multi-population biofilm model, Matsumoto et al. [13] identified that SND via nitrite was feasible in MAB through suitably adjusting the ratios between oxygen and ammonia surface loading and between the COD and nitrogen. Landes et al. [46] illustrated the distinctions among different SND biopathways with the substrate removal characteristics, process contribution and substrate and biomass profiles inside the simulated biofilm by using one-dimensional biofilm models. Systematic performance of AOA-mediating autotrophic MAB has been explored through the mathematical modeling [34]; nonetheless few model-based investigations are available for assessing the nitrogen removal of heterotrophic MAB including AOA transforming ammonia into nitrite and, particularly, elucidating the synergistic and competitive interactions among microbes.
Overall, modeling investigations are extensively around the nitritation/partial nitrification process closely related with the changes of nitrogen forms. But nitrogen is substantially removed through the denitrification. Hence insufficient researches on the denitrification kinetics and the dynamic microbial interactions would hinder the further development and application of SND process. The well-established stoichiometric relationships and major kinetic parameters utilized for mathematical models has been widely adopted from Activated Sludge Models recommended by International Water Association (IWA) [36], mostly determined at temperature of 293 K and neutral pH. Enzyme-catalyzed reactions are intrinsically involved in the BNR process. Consequently, it’s indispensable to identify effects of temperature on the biokinetic process and physiological diversities among microbial communities, which is more valuable in the practical application [47].
This study was aimed to develop a modeling framework to systematically and quantitatively investigate the SND process and microbial interactions within the AOA (55%)-dominating MAB containing certain NOB (15%) and HB (30%) for the treatment of simulated wastewater with low-leveled influent ammonia and soluble organics under different temperatures, aeration pressures and COD/N ratios. The simulation results would preliminarily contribute to directing the AOA-mediating MAB implemented for the enhanced treatment of low strength mainstream in WWTPs and the remediation of micro-polluted surface water and supporting the process operation and optimization of potential biopathways for the proposed BNR system.
Section snippets
Model development
One-dimensional multi-population biofilm model was conducted to simulate bio-conversion processes and dynamic changes of microbial communities during the SND process inside the MAB with the aid of AQUASIM software [48]. The model described the interaction among six soluble components, i.e. degradable COD (SS), ammonia (SNH4), nitrite (SNO2), nitrate (SNO3), nitrogen (SN2) and dissolved oxygen (SO2), and five particulate components, including AOA (XAOA), NOB (XNOB), heterotrophic bacteria (XHB),
Temperature and aeration pressure effects on the nitrogen removal
Effects of temperature on the nitrogen removal of AOA-dominating biofilm in the MAB system was investigated with aeration pressure varied from 0.05 atm to 0.3 atm. According to available report [55], AOA is insensitive to the temperature range in this work, further demonstrated by the ammonia removal efficiency in Table 1. The ammonia concentration in the bulk liquid was maintained at 5.0 gN/m3 (ASL 2 gN/m2·d) to manifest the higher ammonia affinity of AOA. Hence the performance of biofilm with
Conclusion
In this work, the model-based evaluation on the SND process of MAB constituted by AOA (55%), NOB (15%),and HB (30%) for the low-leveled influent ammonia (5 gN/m3) were performed under varied temperatures, aeration pressures and COD/N ratios. Reduced aeration pressures should be applied for higher temperatures to counterbalance the oxygen consumption between the three microbes and achieve higher TN removal performance. Under 293 K and aeration pressure of 0.1 atm, the nitrogen removal was
Acknowledgement
This work was supported by the National Natural Science Foundation of China [Grant Number 51478304].
References (55)
- et al.
Evaluation on the microbial interactions of anaerobic ammonium oxidizers and heterotrophs in anammox biofilm
Water Res.
(2012) - et al.
Heterotrophic activity compromises autotrophic nitrogen removal in membrane-aerated biofilms: results of a modeling study
Water Res.
(2008) - et al.
Nitrification and oxygen utilisation in a membrane aeration bioreactor
J. Membr. Sci.
(1998) The membrane-biofilm reactor (MBfR) as a counter-diffusional biofilm process
Curr. Opin. Biotech.
(2016)- et al.
Feasibility of a membrane-aerated biofilm reactor to achieve controllable nitrification
Biochem. Eng. J.
(2006) - et al.
Simultaneous nitrification and denitrification by controlling vertical and horizontal microenvironment in a membrane-aerated biofilm reactor
J. Biotechnol.
(2003) - et al.
Modeling of membrane-aerated biofilm: effects of C/N ratio, biofilm thickness and surface loading of oxygen on feasibility of simultaneous nitrification and denitrification
Biochem. Eng. J.
(2007) - et al.
Short- and long-term effects of temperature on partial nitrification in a sequencing batch reactor treating domestic wastewater
J. Hazard. Mater.
(2010) - et al.
Bacterial community structure in simultaneous nitrification, denitrification and organic matter removal process treating saline mustard tuber wastewater as revealed by 16S rRNA sequencing
Bioresour. Technol.
(2017) - et al.
Effect of temperature and free ammonia on nitrification and nitrite accumulation in landfill leachate and analysis of its nitrifying bacterial community by FISH
Bioresour. Technol.
(2006)
Autotrophic nitrogen removal in membrane-aerated biofilms: Archaeal ammonia oxidation versus bacterial ammonia oxidation
Chem. Eng. J.
Model-based evaluation on simultaneous nitrate and arsenite removal in a membrane biofilm reactor
Chem. Eng. Sci.
A model-based assessment of nitric oxide and nitrous oxide production in membrane-aerated autotrophic nitrogen removal biofilm systems
J. Membr. Sci.
Model-based evaluation of the role of Anammox on nitric oxide and nitrous oxide productions in membrane aerated biofilm reactor
J. Membr. Sci.
Biodegradation of pharmaceuticals in membrane aerated biofilm reactor for autotrophic nitrogen removal: a model-based evaluation
J. Membr. Sci.
A new approach to simultaneous ammonium and dissolved methane removal from anaerobic digestion liquor: a model-based investigation of feasibility
Water Res.
Model-based evaluation of temperature and inflow variations on a partial nitrification–ANAMMOX biofilm process
Water Res.
Sulfide removal and sulfur production in a membrane aerated biofilm reactor: model evaluation
Chem. Eng. J.
The anaerobic oxidation of ammonium
FEMS Microbiol. Rev.
Temperature dependency of biological denitrification with organic materials addition
Water Res.
Bioremediation of ammonia from polluted waste waters–a review
Eur. J. Obstet. Gynecol. Reprod. Biol.
Effective biological nitrogen removal treatment processes for domestic wastewaters with low C/N ratios: a review
Environ. Eng. Sci.
Feasibility of Mainstream Nitrite Oxidizing Bacteria Out-selection and Anammox Polishing for Enhanced Nitrogen Removal
Biological nitrogen removal with nitrification and denitrification via nitrite pathway
Appl. Microbiol. Biotechnol.
Stratification of activity and bacterial community structure in biofilms grown on membranes transferring oxygen
Appl. Environ. Microbiol.
Redox-stratification controlled biofilm (ReSCoBi) for completely autotrophic nitrogen removal: the effect of co- versus counter-diffusion on reactor performance
Biotechnol. Bioeng.
Sequential aeration of membrane-aerated biofilm reactors for high-rate autotrophic nitrogen removal: experimental demonstration
Environ. Sci. Technol.
Cited by (31)
Genetic programming expressions for effluent quality prediction: Towards AI-driven monitoring and management of wastewater treatment plants
2024, Journal of Environmental ManagementMembrane aerated biofilm reactor system driven by pure oxygen for wastewater treatment
2024, Bioresource TechnologyDeveloping the mathematical model to predict the nitrogen removal and N<inf>2</inf>O emission by the biological aerated filter
2023, Journal of Water Process EngineeringThe membrane aerated biofilm reactor for nitrogen removal of wastewater treatment: Principles, performances, and nitrous oxide emissions
2023, Chemical Engineering JournalModelling the impacts of operational conditions on the performance of a full-scale membrane aerated biofilm reactor
2023, Science of the Total EnvironmentCitation Excerpt :Results reported in this study are in good agreement with previous modelling studies published in specialized literature. The same AOB and OHO distribution within the biofilm could be found in Lackner et al. (2008), Wang et al. (2009), Ni et al. (2013), Chen et al., 2016) and Li et al. (2018). The effect of organic substrates and the competition between AOB and OHO is also studied reaching similar conclusions as in this manuscript.