Partial nitritation of nitrogen-rich refinery wastewater (sour water) with different C_i/N molar ratios

Abstract

In this study, a SHARON reactor was used to treat synthetic and real ammonium-rich refinery wastewater (sour water) with different inorganic carbon to nitrogen (C_i/N) molar ratios, in order to evaluate its possible implementation downstream of a steam stripping unit in a double-stage SHARON–ANAMMOX or SHARON–heterotrophic denitritation process. A synthetic influent containing -N (2,000 mg/L) was initially fed to promote biomass acclimation, and then real sour water containing also organic substrate, cyanides, sulphides and phenols was supplied. With both synthetic and real wastewater, the applied C_i/N molar ratio was progressively increased from 1 to 2 and the SHARON reactor produced an effluent suitable for further treatment by autotrophic ANAMMOX or heterotrophic denitritation, respectively. Acute toxicity assessments based on the specific measurement of nitritation activity confirmed that biomass acclimation to the toxic substances contained in the real wastewater occurred successfully. Moreover, high removal of organic matter (73 ± 12%) suggested the absence of any competition between heterotrophic and autotrophic micro-organisms. Controlling influent C_i/N molar ratio was shown to represent a key operating strategy to properly regulate SHARON performance, depending on the chosen downstream treatment, proving its actual feasibility under harsh operating conditions and providing useful indications for its implementation at full scale.

Keywords:

• Alkalinity
• Ammonium
• Industrial wastewater
• Nitrogen removal
• Partial nitritation
• SHARON

Acknowledgements

This research was financially supported by SARAS SpA and Fondazione Banco di Sardegna. The authors wish to thank SARAS SpA also for supplying the real wastewater used in the experiments. M. Perra gratefully acknowledges Sardinia Regional Government for the financial support of her PhD scholarship (P.O.R. Sardegna F.S.E. Operational Programme of the Autonomous Region of Sardinia, European Social Fund 2007–2013—Axis IV Human Resources, Objective I.3, Line of Activity I.3.1).

Notes

Presented at the 13th International Conference on Environmental Science and Technology (CEST 2013), 5–7 September 2013, Athens, Greece