Performance Evaluation of a Marshland Upwelling System for the Treatment ofDomestic Wastewater from Coastal Dwellings

摘要

Currently approved on-site treatment techniques (I.e. Septic systems and adsorption fields) are severely impairedrnin the saturated, tidally influenced soils of coastal regions and can contribute to water quality problems. ThernMarshland Upwelling System (MUS) is a decentralized treatment strategy designed specifically for the uniquernhydrogeological conditions of coastal zones. The MUS uses the soil's natural filtration properties and densityrndifferences between the wastewater and saline subsurface to provide cost-effective, low-maintenance treatment.rnCosts are limited to operation of an injection pump that intermittently delivers wastewater down a shallow (12-15rnft), Class V well. Upon injection, the waste percolates upwards through the media in the direction of decreasingrndensity prompting waste stabilization prior to reaching the ground surface.rnThe nine-year, on-going study has focused primarily on system's efficacy in removing fecal pathogens fromrnsettled and secondary domestic wastewater sources. The MUS has reduced coliform bacteria concentrations tornbelow standards for shellfishing and recreational waters in the Scatlake soils and salinity regime found at the PortrnFourchon, LA experimental site. Optimal performance was achieved at a flowrate of 1.9 L/min when injectedrnintermittently for 30 minutes every 3 hours. Informal results also revealed extreme reductions in influent BOD.rnAn additional pilot system has been installed along Bayou Cumbest in Moss Point, MS to evaluate its ability tornprovide total treatment under different soil types and salinity profiles. Nutrient, organic, and bacterial removal isrnlargely dependent on the wastewater plume dynamics. Thus, evaluation of the fundamental mechanismsrnresponsible for plume development is a primary concern. Preliminary data concerning the fate and transport ofrnfecal coliform bacteria and organic matter (CBOD5) will be presented. The ultimate goal of the MUS project is torndevelop operational criteria, based upon economical and ecological concerns, in hopes of providing an approved,rneffective treatment alternative for coastal dwellings.