Effect of carbon-to-nitrogen ratio on simultaneous nitrification denitrification and phosphorus removal in a microaerobic moving bed biofilm reactor

Francesca Iannacone; Francesco Di Capua; Francesco Granata; Rudy Gargano; Francesco Pirozzi; Giovanni Esposito

doi:10.1016/j.jenvman.2019.109518

Effect of carbon-to-nitrogen ratio on simultaneous nitrification denitrification and phosphorus removal in a microaerobic moving bed biofilm reactor

J Environ Manage. 2019 Nov 15:250:109518. doi: 10.1016/j.jenvman.2019.109518. Epub 2019 Sep 10.

Authors

Francesca Iannacone¹, Francesco Di Capua², Francesco Granata¹, Rudy Gargano¹, Francesco Pirozzi³, Giovanni Esposito³

Affiliations

¹ Department of Civil and Mechanical Engineering, University of Cassino and Southern Lazio, via Gaetano di Biasio 43, 03043, Cassino, Italy.
² Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, 80125, Naples, Italy. Electronic address: francesco.dicapua2@unina.it.
³ Department of Civil, Architectural and Environmental Engineering, University of Naples Federico II, via Claudio 21, 80125, Naples, Italy.

PMID: 31518800
DOI: 10.1016/j.jenvman.2019.109518

Abstract

In this study, long-term simultaneous nitrification denitrification (SND) and phosphorous removal were investigated in a continuous-flow microaerobic MBBR (mMBBR) operated at a dissolved oxygen (DO) concentration of 1.0 (±0.2) mg L^-1. The mMBBR performance was evaluated at different feed carbon-to-nitrogen (C/N) ratios (2.7, 4.2 and 5.6) and HRTs (2 days and 1 day). Stable long-term mMBBR operation and chemical oxygen demand (COD), total inorganic nitrogen (TIN) and phosphorous (P-PO₄^3-) removal efficiencies up to 100%, 68% and 72%, respectively, were observed at a feed C/N ratio of 4.2. Lower TIN removal efficiency and unstable performance were observed at feed C/N ratios of 2.7 and 5.6, respectively. HRT decrease from 2 days to 1 day resulted in transient NH₄⁺ accumulation and higher NO₂^-/NO₃^- ratio in the effluent. Batch activity tests showed that biofilm cultivation at a feed C/N ratio of 4.2 resulted in the highest denitrifying activity (189 mg N gVSS^-1 d^-1), whereas the highest nitrifying activity (316 mg N gVSS^-1 d^-1) was observed after cultivation at a feed C/N ratio of 2.7. Thermodynamic modeling with Visual MINTEQ and stoichiometric evaluations revealed that P removal was mainly biological and can be attributed to the P-accumulating capacity of denitrifying bacteria.

Keywords: Microaerobic operation; Moving bed biofilm reactor; Nutrient removal; Phosphorous removal; Simultaneous nitrification denitrification.

MeSH terms

Biofilms
Bioreactors
Carbon
Denitrification*
Nitrification*
Nitrogen
Phosphorus
Sewage
Waste Disposal, Fluid
Wastewater

Substances

Sewage
Waste Water
Phosphorus
Carbon
Nitrogen