Renovation of Filtered Primary Effluent During Simulated Soil Aquifer Treatment (SAT)

Abstract

Soil aquifer treatment (SAT) for filtered primary effluent was simulated using two 1-m plexiglass columns (7 .62 cm i.d.) packed with sandy loam soil. When 0 2 was available, the organic levels achieved (mean DOC: 5.5 mg/1, mean UV A254: 0.1 cm-1) in the renovated water were not significantly different from those obtained when secondary eflluents are used. The combination of aerobic processes coupled with sorption and filtration were responsible for the removal of particulate (mean turbidity: 0.77 N.T.U.) and dissolved organic matter. Continuous 0 2 availability tended to block denitrification reactions causing nitrification to control the fate and transport of nitrogen species. The denitrification potential of filtered primary effluent, reflected in 32-57% overall nitrogen removals, was confirmed by nitrate effluent spiking and oxygen limited conditions with the decrease in organics removals. Relatively little phosphorus was retained through one-meter depth of soil during SAT. Significant removals on total (3-5 log units) and fecal (close and below detection limits) coliforms were achieved under continuous 0 2 availability. Coliphage removal efficiency, however, was less (