Treatment of wastewater ammonium under varying salinity conditions within the marshland upwelling system

ABSTRACT

Coastal wetlands and estuaries are impacted by nutrient loads from a variety of sources including infrequently occupied hunting and fishing camps. The marshland upwelling system (MUS) was designed to treat wastewater in the coastal environment where traditional septic systems or centralized wastewater collection and treatment are not viable. A laboratory macrocosm study was designed to simulate field conditions in which domestic wastewater is treated via injection into a marsh subsurface. Treatment of wastewater nitrogen (N) utilizing the MUS was examined under high (∼20 ppt) and low (∼2 ppt) salinity conditions. Two N wastewater solutions were used, one treatment consisted of 100 mg NH₄-N L⁻¹, while a second treatment consisted of 80 mg NH₄-N L⁻¹/20 mg NO₃-N L⁻¹. The 20 ppt salinity treatment was found to have a negative impact on NH₄-N sorption. The potentially mineralizable N rate was higher in the low salinity treatment, which could potentially be offset by the higher sorption capacity at lower salinities. The background salinity of the local groundwater should be considered as the salinity will play a role in the longevity of the system.

GRAPHICAL ABSTRACT

KEYWORDS:

• Wastewater treatment
• treatment wetland
• ammonium
• salinity
• sorption

Acknowledgements

The authors would like to thank Adam Janot, Michael McCracken, Dhaval Shah, Erika Hamm, and Maverick LeBlanc for their help in this research. We are also extremely grateful to Louisiana Sea Grant for funding this research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Louisiana Sea Grant, Louisiana State University [grant number NA06OAR4170022].