Dear Colleagues,

Nitrogen is one of the most concerning constituents that threatens aquatic ecosystems worldwide. Throughout the history of wastewater treatment, nitrogen has been one of the primary target contaminants to remove, and therefore much effort has been spent on its removal. However, the environmental problems that nitrogen causes are still unsolved in many regions, in which surface and/or groundwater with high and stable concentrations of nitrogen can still be found, severely affecting water bodies and their flora and fauna.

In addition to the different sites and engineered ecosystems where nitrogen contamination are important, there has been brilliant work done on the development of novel technologies for the treatment of nitrogen in wastewater, such as those based on electrochemical processes or mediated by recently discovered metabolisms of novel microorganisms such as DPANN archaeal members, which promote different pathways for nitrogen removal and/or add value to the removal of nitrogen from wastewater or groundwater.

For these reasons, this Special Issue becomes of importance for the field of nitrogen removal from wastewater. The dissemination of research that can cast light on ecological systems under nitrogen stress and in situ remediation techniques, as well as new advances on recently developed nitrogen removal mechanisms that can compete with the traditional systems, is fundamental to the continued mitigation of the impact that this contaminant is still generating on our aquatic ecosystems.

Thus, this new Special Issue of Water titled ‘Removal of nitrogen from wastewater and groundwater’ will gather contributions on these topics:

• Novel processes for removal of nitrogen from wastewater and groundwater;
• In situ remediation techniques for aquatic environments under nitrogen pollution stresses.

Dr. Alejandro Rodriguez-Sanchez
Guest Editor

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• denitrification
• anaerobic ammonium oxidation (anammox)
• nitrite/nitrate-dependent anaerobic methane oxidation (n-DAMO)
• bioelectrochemical processes
• eutrophication
• groundwater
• wetlands
• agriculture runoff
• granular sludge
• membrane processes