Comparative analysis of nitrogen removals and microbial communities in air and pure oxygen aeration systems during treatment of municipal solid waste incineration (MSWI) leachate

https://doi.org/10.1016/j.jwpe.2022.102900Get rights and content

Highlights

  • The nitrogen removal capacity was improved when PO aeration was used instead of air aeration.

  • The abundance of functional taxa, such as AOB and DNB, was increased with using the PO aeration.

  • The autotrophic- and nitrite- denitrification was enhanced with using the PO aeration.

  • In-depth analysis/characterization of many unclassified taxa involved in denitrification pathway.

Abstract

MSWI leachate contain high concentrations of ammonium nitrogen (NH4+-N). The conventional submerged air-diffusing (CSA) system are the dominant oxygen supply in the aerobic process for NH4+-N removal from leachate. However, it carries high energy consumption. In this study, Pure oxygen (PO), which is more environmentally friendly, was used as an alternative to air for solving this problem. For comprehensive analysis the effects of PO supersede air on nitrogen removals and microbial diversities in the aerobic process during treatment of MSWI leachate, two parallel full-scale anoxic-oxic systems were set with the floating Praxair's in situ oxygenation (I-SO™) system and the CSA system, respectively. Compared to the CAS system, the removal efficiency of total nitrogen (TN) increased by 9.79% with the I-SO™ system but COD and NH4+-N removals reduced by 6.83% and 1.19%, respectively. Metagenomic studies revealed that the bacterial richness, diversity, and evenness decreased with PO aeration, while the abundances of ammonia-oxidizing bacteria (AOB) and denitrifying bacteria (DNB) increased, as well as the AOB/nitrite-oxidizing bacteria (NOB) ratios. In addition, the nitrite-denitrification functional genes (nirK and nirS) deposited from autotrophic and Heterotrophic bacteria were more predominant and accounted for the higher efficiency of TN removal in the PO aeration treatment, while complete nitrification and nitrate-denitrification were dominant in the air aeration anoxic-oxic system. Therefore, nitrogen removal from MSWI leachate by using PO aeration provided theoretical perspective for engineering applications.

Introduction

Prior to the onsite incineration of municipal solid waste (MSW), it is usually settled in the waste bunker for 2–7 days to further reduce water content. During the process, a large amount of fresh leachate (MSWI leachate) is generated, which contains high contents of COD (20000–75,000 mg/L), NH4+-N (1000–3000 mg/L) and suspended solids (SS) (1000–5000 mg/L), as well as the refractory organic matters (e.g., fulvic- and humic-like substances) [1], [2], [3]. This leachate poses a threat to the environments, and needs to be safely treated before water reclaiming or directly discharging into sewage system. In a typical MSWI leachate, the ratio of biological oxygen demand (BOD5) to COD varies between 0.5 and 0.8 [4], which is suitable for and quite effective with the treatment of biological systems, such as anaerobic-aerobic-coagulation process [5], anaerobic baffled reactor (ABR)-aerobic process [6], and UASB-modified Bardenpho process [4].

In the biological treatment, aerobic process is the key step for completely degradation of pollutants, in which sufficient oxygen is supplied for boosting the proliferation of aerobic microorganisms and secretions of enzymes that engaged in degrading COD and converting ammonia to nitrate. Since oxygen only account for 21% in the air, large volume of air should be used for the treatment of high-strength leachate with the conventional air-diffusing aeration system. The excessive air aeration would cost a great deal of energy. Furthermore, severely undesired foams, volatile organic chemicals (VOCs) and other malodorous gases would derive from the high intensity air aeration [7]. As the PO partial pressure is 4.7 times higher than that of air, it can improve the oxygen transfer rate (OTR) and maintain high DO level with a lower flowrate during treatment of high concentration wastewater [8]. Previous studies reported that removal efficiencies of COD [9], total organic carbon (TOC) [10] and NH4+-N [11] were enhanced by using PO aeration in the aerobic process. To date, PO aeration has been applied for treatment of different wastewater with high-strength, including landfill leachate [12], [13], pulp and paper wastewater [14], and coal gasification wastewater [9]. Zhuang et al. reported that under the PO aeration, some species of microorganisms involved in nitrification and denitrification were enriched, which included Thauera, Comamonas, Nitrosomonas and Nitrospira [9]. However, few investigations was carried out on PO aeration for treatment of MSWI leachate, and its effects on removals and metabolism pathways of nitrogen were not fully illustrated.

To elucidate the potential effects of PO supersede air on nitrogen removals and microbial diversities, air and PO aeration were respectively applied in the aerobic processes of two full-scale anoxic-oxic systems operated in parallel for treatment of MSWI leachate. In this study, the performances of nitrogen removals were investigated, and the nitrogen metabolism mechanisms were comprehensively elucidated by metagenomics. The main objectives of this study were to (1) compare nitrogen removals with air and PO aeration; (2) identify the structures of microbial communities and their functions in nitrogen metabolism in the two systems; (3) recover the genomes of poorly-characterized microbial species, and identify their roles in nitrification and denitrification; and (4) illustrate the pathways for nitrogen removal under the air and PO aeration. To our knowledge, this work was the first time to use the metagenomic sequencing approach to compare the microbial communities and their metabolic functions in nitrogen removal under the air and PO aeration in full-scale biological treatment systems. These results would elucidate the mechanism of nitrogen removal in treatment of high strength (organic and ammonia) wastewater streams from the perspective of metagenomes.

Section snippets

Full-scale anoxic-oxic systems operated in parallel

The raw MSWI leachate was collected from an MSW incineration plant located in Changzhou (ca 31.72°N, 120.05°E), China. The original MSWI leachate treatment system was operated with a designed capacity of 400 m3/d as illustrated in Fig. S.1, which contained an equalization tank, anaerobic digestion towers, the same-sized two anoxic-oxic biological treatment systems operated in parallel (anoxic tank: 375 m3, the first oxic tanks: 877 m3; the second oxic tanks: 364 m3), and ultra-, nano- and

Performance of two full-scale anoxic-oxic systems

The removal efficiencies of COD, NH4+-N and TN, and the changes of NO2-N and NO3-N, in the two systems with either air or PO aeration were demonstrated in Fig. 1A–D. As shown in Fig. 1A, the influent COD was ranged from 3508 mg/L to 6163 mg/L. After treatment with the anoxic-oxic systems, CODs in the effluent of AAT and POAT were steadily around 993 mg/L and 1231 mg/L, respectively, which corresponded to 78% and 73% of the average COD removal efficiencies. In leachate, in addition to the

Conclusions

In this study, a full-scale experimental investigation of the effects of PO supersedes air on nitrogen removal and microbial communities for MSWI leachate treatment. During the experimental period, better TN removal and better COD and NH4+-N removal were obtained in POAT and AAT, respectively. Compared to air aeration, the special distribution of oxygen created by PO aeration had a remarkable influence on microbial community structures and functions, which enhanced autotrophic denitrification

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research is financially supported by the National Key Research and Development Program of China (NO. 2022YFE011372 and No. 2019YFC0408605), Research Project of Guangzhou Municipal Science and Technology Bureau (No. 201903010035) and Key-Area Research and Development Program of Guangdong Province (No. 2019B110209002). Thanks Dr. Y. Yu of Taiyuan Shengjie Science and Technology Company for the valuable advices in revision.

References (71)

  • K. Bernat et al.

    Microfauna community during pulp and paper wastewater treatment in a UNOX system

    Eur. J. Protistol.

    (2017)
  • C.J. Chen et al.

    TBtools: an integrative toolkit developed for interactive analyses of big biological data

    Mol. Plant

    (2020)
  • D.H. Li et al.

    MEGAHIT v1.0: a fast and scalable metagenome assembler driven by advanced methodologies and community practices

    Methods

    (2016)
  • M. Kanehisa et al.

    BlastKOALA and GhostKOALA: KEGG tools for functional characterization of genome and metagenome sequences

    J. Mol. Biol.

    (2016)
  • Y.Q. Lei et al.

    Metagenomic analysis reveals that activated carbon aids anaerobic digestion of raw incineration leachate by promoting direct interspecies electron transfer

    Water Res.

    (2019)
  • J. Liu et al.

    Influence of reflux ratio on two-stage anoxic/oxic with MBR for leachate treatment: performance and microbial community structure

    Bioresour. Technol.

    (2018)
  • J. Liu et al.

    Two-stage anoxic/oxic combined membrane bioreactor system for landfill leachate treatment: pollutant removal performances and microbial community

    Bioresour. Technol.

    (2017)
  • J.H. Chen et al.

    Dynamics of nitrogen transformation and bacterial community with different aeration depths in malodorous river

    World J. Microb. Biot.

    (2019)
  • X. Huang et al.

    Sludge alkaline fermentation enhanced anaerobic- multistage anaerobic/oxic (A-MAO) process to treat low C/N municipal wastewater: nutrients removal and microbial metabolic characteristics

    Bioresour.Technol.

    (2020)
  • Z. Luo et al.

    The effect of using pig manure as an internal carbon source in a traditional piggery wastewater treatment system for biological denitrification

    Ecol. Eng.

    (2020)
  • Q.Z. Zeng et al.

    Effect of Fe3O4 nanoparticles exposure on the treatment efficiency of phenol wastewater and community shifts in SBR system

    J. Hazard. Mater.

    (2021)
  • N. McKenzie et al.

    Biodegradation of naphthenic acids in oils sands process waters in an immobilized soil/sediment bioreactor

    Chemosphere

    (2014)
  • Z.C. Xu et al.

    Combined heterotrophic and autotrophic system for advanced denitrification of municipal secondary effluent in full-scale plant and bacterial community analysis

    Sci. Total Environ.

    (2020)
  • W.Y. Huang et al.

    Effect of anaerobic/aerobic duration on nitrogen removal and microbial community in a simultaneous partial nitrification and denitrification system under low salinity

    Sci. Total Environ.

    (2019)
  • C. Ospina-Betancourth et al.

    Low inhibitory effect of ammonia on the nitrogen-fixing activity of a sludge enriched with nitrogen-fixing bacteria

    Bioresour.Technol.Rep.

    (2021)
  • T. Zhang et al.

    Coupled effects of methane monooxygenase and nitrogen source on growth and poly-beta-hydroxybutyrate (PHB) production of Methylosinus trichosporium OB3b

    J. Environ. Sci. (China)

    (2017)
  • L.Y. Stein

    Insights into the physiology of ammonia-oxidizing microorganisms

    Curr. Opin. Chem. Biol.

    (2019)
  • J. Crovadore et al.

    Metatranscriptomic and metagenomic description of the bacterial nitrogen metabolism in waste water wet oxidation effluents

    Heliyon

    (2017)
  • R. Yu et al.

    Nitrosomonas europaea adaptation to anoxic-oxic cycling: insights from transcription analysis, proteomics and metabolic network modeling

    Sci. Total Environ.

    (2018)
  • W.L. Jia et al.

    Nitrous oxide emission in low-oxygen simultaneous nitrification and denitrification process: sources and mechanisms

    Bioresour.Technol.

    (2013)
  • H. Jiang et al.

    Advanced nitrogen removal from mature landfill leachate via partial nitrification-anammox biofilm reactor (PNABR) driven by high dissolved oxygen (DO): protection mechanism of aerobic biofilm

    Bioresour. Technol.

    (2020)
  • G. Ciudad et al.

    Differential kinetics of ammonia- and nitrite-oxidizing bacteria: a simple kinetic study based on oxygen affinity and proton release during nitrification

    Process Biochem.

    (2006)
  • Q.W. Sui et al.

    Multiple strategies for maintaining stable partial nitritation of low-strength ammonia wastewater

    Sci. Total Environ.

    (2020)
  • F.A. Rodriguez et al.

    Comparative study of the use of pure oxygen and air in the nitrification of a MBR system used for wastewater treatment

    Bioresour. Technol.

    (2012)
  • F. Fang et al.

    Anaerobic/aerobic/coagulation treatment of leachate from a municipal solid wastes incineration plant

    Environ. Technol.

    (2012)
  • Cited by (0)

    View full text