Fecal Bacteria Removal and Background Recovery Within the Marshland Upwelling System

摘要

The marshland upwelling system (MUS) was developed as an onsite wastewater treatment approach for coastal dwellings. The MUS removes fecal bacteria in injected wastewater by utilizing the processes of filtration, straining, adsorption, predation, and die-off through saturated subsurface sediments. The objective of this research was to evaluate the long-term sustainability of the MUS by evaluating removal efficiency of fecal bacteria from raw wastewater and assessing the system background recovery after the MUS stopped operation. Based on 32-month monitoring on an MUS site located in Bayou Segnette Canal Waterway, Louisiana, we found that the MUS compared well with other constructed wetland systems. The MUS showed an enhanced efficacy of fecal bacteria removal after long-time operation due to the deposition of solid particles from primary wastewater and the growth of biofilm in subsurface over time. Moreover, the background recovery study indicates that the subsurface environment has recovered completely from the MUS fecal bacteria loading in less than 4 months after the MUS shut down. Natural die-off was the dominant kinetic account for the fecal bacteria level returning to baseline prior to system initiation. In conclusion, the long-term monitoring results suggest the MUS a sustainable wastewater treatment alternative for coastal dwellings.