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Salinity effect on freshwater Anammox bacteria: Ionic stress and ion composition
Limin Lin1, Steven Pratt1, Oliver Crick1
1School of Chemical Engineering, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia.
Water Research
|October 17, 2020
Summary
High salinity inhibits freshwater Anammox bacteria (FAB) crucial for wastewater treatment. This study reveals specific ion effects and mechanisms, showing both ionic stress and composition contribute to inhibition.
Area of Science:
- Environmental microbiology
- Wastewater treatment technologies
- Anammox process
Background:
- Salinity poses a challenge for Anammox application in wastewater treatment.
- Previous research focused on osmotic effects, neglecting ion composition impacts on freshwater Anammox bacteria (FAB).
Purpose of the Study:
- To investigate the individual and combined inhibitory effects of NaCl, KCl, and Na2SO4 on FAB.
- To elucidate the mechanisms of salinity inhibition by analyzing gene expression.
Main Methods:
- Batch tests were conducted to assess FAB inhibition by different salts.
- mRNA abundance of nitrite reductase (nirS), hydrazine synthase (hzsB), and hydrazine dehydrogenase (hdh) genes were analyzed.
Main Results:
- NaCl, KCl, and Na2SO4 exhibited varying inhibition levels (EC50: 0.106 M, 0.096 M, 0.063 M, respectively).
- Combined salt inhibition showed synergistic effects for NaCl+KCl and NaCl+Na2SO4, and additive effects for NaCl+KCl+Na2SO4.
- Gene expression analysis indicated NaCl inhibited ammonium transport, Na2SO4 inhibited both nitrite and ammonium transport, and high salinity reduced enzyme activity.
Conclusions:
- Both ionic stress and specific ion composition contribute to salinity inhibition of FAB.
- Understanding these mechanisms is vital for optimizing Anammox processes in high-salinity wastewater.
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