Performance evaluation of a Marshland Upwelling System for the removal of fecal coliform bacteria from domestic wastewater.
The Marshland Upwelling System (MUS), a potential alternative wastewater treatment strategy for coastal dwellings, was examined to assess its ability to remove fecal coliforms (FC) from domestic wastewater as a step towards total treatment. Wastewater was intermittently injected down a 4.6-m injection well into the surrounding salt marsh. Optimal performance was achieved at an injection flowrate of 1.9 L/min and injection frequency of 30 minutes every 3 hours. Average influent concentrations of 930,000+/-650,000 colonies/100 mL, were reduced to effluent counts of 4.6 colonies/100 mL. Coliform removal followed exponential decay versus vector distance traveled with predicted surface concentrations less than or equal to 0.1 colony/100 mL. Hydraulic performance was acceptable with no significant reductions in permeability observed. Increasing flows to 3.8 L/min produced localized hydraulic dysfunction as indicated by sudden increases in effluent bacterial counts and injection pressures. Although fecal coliform removal typically decreased with increasing injection flowrates and isolated instances of abnormally high effluent counts were observed the MUS never experienced a catastrophic failure during the 13-month evaluation period.
Watson
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Department of Civil and Environmental Engineering at Louisiana State University, Baton Rouge 70808-6405, USA.
Rusch
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D017753:Ecosystem; D004755:Enterobacteriaceae; D004867:Equipment Design; D011312:Pressure; D012037:Refuse Disposal; D014872:Water Movements