References
   -  N. Fernández-Nava, E. Marañón, J. Soons, L. Castrillón,
    Denitrification of high nitrate concentration wastewater
    using alternative carbon sources, J. Hazard. Mater., 173 (2010)
    682–688. 
 
  -  Y.-Q. Liu, B.Y.-P. Moy, J.-H. Tay, COD removal and nitrification
    of low-strength domestic wastewater in aerobic granular sludge
    sequencing batch reactors, Enzyme Microb. Technol., 42 (2008)
    23–28. 
 
  -  M. Henze, Capabilities of biological nitrogen removal processes
    from wastewater, Water Sci. Technol., 23 (1991) 669–679. 
 
  -  A. di Biase, M.S. Kowalski, T.R. Devlin, J.A. Oleszkiewicz,
    Moving bed biofilm reactor technology in municipal wastewater
    treatment: a review, J. Environ. Manage., 247 (2019) 849–866. 
 
  -  S.H. Song, S.S. Choi, K. Park, Y.J. Yoo, Novel hybrid
    immobilization of microorganisms and its applications to
    biological denitrification, Enzyme Microb. Technol., 37 (2005)
    567–573. 
 
  -  Z. Mavriou, I. Alexandropoulou, P. Melidis, D.G. Karpouzas,
    S. Ntougias, Biotreatment and bacterial succession in an
    upflow immobilized cell bioreactor fed with fludioxonil
    wastewater, Environ. Sci. Pollut. Res., 28 (2021) 3774–3786. 
 
  -  X. Xu, Z. Jin, B. Wang, C. Lv, B. Hu, D. Shi, Treatment of highstrength
    ammonium wastewater by polyvinyl alcohol–sodium
    alginate immobilization of activated sludge, Process Biochem.,
    63 (2017) 214–220. 
 
  -  H. Bae, M. Choi, Y.-C. Chung, S. Lee, Y.J. Yoo, Core-shell
    structured poly(vinyl alcohol)/sodium alginate bead for singlestage
    autotrophic nitrogen removal, Chem. Eng. J., 322 (2017)
    408–416. 
 
  -  Y.S. Ge, A. Yamaguchi, H. Sakuma, Study on the performance
    of anaerobic ammonium oxidation treatment using PVA gel as
    a carrier, Water Sci. Technol., 59 (2009) 1037–1041. 
 
  -  M.S. Jetten, S. Logemann, G. Muyzer, L.A. Robertson, S. de
    Vries, M.C. van Loosdrecht, J.G. Kuenen, Novel principles in
    the microbial conversion of nitrogen compounds, Antonie
    Van Leeuwenhoek, 71 (1997) 75–93. 
 
  -  C.Y. Wan, H.D. Wever, L. Diels, C. Thoeye, J.B. Liang, L.N. Huang,
    Biodiversity and population dynamics of microorganisms in
    a full-scale membrane bioreactor for municipal wastewater
    treatment, Water Res., 45 (2011) 1129–1138. 
 
  -  H. Man, X. Wang, X. Wen, X. Yu, Microbial community
    structures in different wastewater treatment plants as revealed
    by 454-pyrosequencing analysis, Bioresour. Technol., 117 (2012)
    72–79. 
 
  -  H. Koch, M.V. Kessel, S. Lücker, Complete nitrification:
    insights into the ecophysiology of comammox Nitrospira,
    Appl. Microbiol. Biotechnol., 1 (2019) 177–189. 
 
  -  Y.S. Luo, J.Q. Yao, X.Y. Wang, M.Y. Zheng, D.Y. Guo, Y.G. Chen,
    Efficient municipal wastewater treatment by oxidation ditch
    process at low temperature: bacterial community structure
    in activated sludge, Sci. Total Environ., 703 (2019) 135031,
    doi: 10.1016/j.scitotenv.2019.135031. 
 
  -  Y.M. Chang, Q. Yang, C.B. Hao, H.T. Shang, T.S. Jiang,
    Experimental study of autotrophic denitrification bacteria
    through bioaugmentation of activated sludge from municipal
    wastewater plant, Environ. Sci. (Chin. J.), 32 (2011) 1210–1216. 
 
  -  B. Ji, K. Yang, L. Zhu, Y. Jiang, H.Y. Wang, J. Zhou, H.N. Zhang,
    Aerobic denitrification: a review of important advances of the
    last 30 years, Biotechnol. Bioprocess Eng., 20 (2015) 643–651. 
 
  -  A. Rajta, R. Bhatia, H. Setia, P. Pathania, Role of heterotrophic
    aerobic denitrifying bacteria in nitrate removal from wastewater,
    J. Appl. Microbiol., 128 (2019) 1261–1278. 
 
  -  Y.L. Gan, Q.L. Zhao, Z.F. Ye, Denitrification performance
    and microbial diversity of immobilized bacterial consortium
    treating nitrate micro-polluted water, Bioresour. Technol.,
    281 (2019) 351–358. 
 
  -  G.L. Wang, M. Bi, B. Liang, J.D. Jiang, S.P. Li, Pseudoxanthomonas
    jiangsuensis sp. nov., a DDT-degrading bacterium isolated from
    a long-term DDT-polluted soil, Curr. Microbiol., 62 (2011)
    1760–1766. 
 
  -  N.H. Sajith Madhawa Premarathna M.Eng., C. Visvanathan,
    Enhancement of organic matter and total nitrogen removal in a
    membrane aerated biofilm reactor using PVA-Gel bio-carriers,
	  Bioresour. Technol. Rep., 8 (2019) 1–8.