| Summary: | The Marshland Upwelling System (MUS) is an alternative onsite wastewater treatment technology designed to utilize the natural ecology of saltwater marshes to remove human-borne contaminants. Over the past twelve years, MUSs have been installed in Port Fourchon, Louisiana, Moss Point, Mississippi, and Bayou Segnette, Louisiana. The purpose of this study was to investigate the nitrogen reduction capabilities of the Bayou Segnette system. The objectives of this research were to: 1) determine the first-order removal constants necessary for the development of nitrogen transport equations, 2) explore the spatial dependencies of nitrogen concentrations within the Bayou Segnette system, and 3) determine the nitrogen adsorptive capacities of the Bayou Segnette and Moss Point soil matrices.
The Bayou Segnette system was operated under three flow regimes. Flow regimes producing lower hydraulic loading rates provided greater nitrogen reduction at shorter travel distances. Overall removal efficiencies were in excess of 98% for TAN and 96% for TKN. A spatial trend, evident during each of the flow regimes, was characterized by increasing TAN concentrations in a northwest direction. Subsurface TAN concentrations were spatially correlated and successfully modeled using regression-kriging. The ammonium adsorptive capacities of Bayou Segnette and Moss Point soils were quantified using batch shake tests and modeled using sorption isotherms. In most instances, the Langmuir sorption isotherm provided better data estimates at higher aqueous concentrations. However, the linear sorption isotherm adequately modeled ammonium adsorption at dilute locations away from the point of injection.
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