Ammonium removal by partial nitritation and Anammox processes from wastewater with increased salinity

Abstract

This work is dedicated to the biological treatment of wastewater with increased salinity using a combination of partial nitritation and Anammox processes. Two one-stage deammonification moving bed biofilm reactors were operated with the increase in NaCl concentration every two weeks by 5 and 2.5 g/L. The strategy with a step of 5 g/L of salinity increase led to complete inhibition of the process at the salinity level of 15 g/L. The strategy with a step of 2.5 g/L gave possibility to adapt bacteria to the elevated salinity. After reaching the salinity level of 10 g NaCl/L, the reactor was operated during 92 days with a nitrogen removal rate of 0.39 ± 0.19 g N/(m²·day) (0.078 ± 0.038 kg N/m³·day) and an average nitrogen removal efficiency of 59%. It was shown that conductivity cannot be used for monitoring the process when a reactor is treating wastewater with increased salinity, whereas pH can be correlated to effluent ammonium concentration regardless of wastewater salinity.

Keywords:

• wastewater
• ammonium
• nitrification
• Anammox
• activity

Acknowledgement

Financial support for research by Swedish Water Development (SVU) is greatly appreciated. We gratefully acknowledge scholarships provided by Swedish Institute and Ministry of Education and Science of Ukraine to Andriy Malovanyy for his PhD studies. The experimental work was performed at Hammarby Sjöstadsverk (Swedish Water Innovation Center), Stockholm, Sweden. Help of Xin Zhang and Arslan Ahmad with operation of reactors is highly appreciated.