WRRCTR No.102 Nitrogen Removal from Secondary Effluent by a Laboratory Soil Column

Abstract

The objective of the project was the investigation of the percolate rate and the disposition of nitrogen from a laboratory soil column when chlorinated secondary sewage effluent was applied under both continuous and intermittent loading. A 1.7-m (5.5-in.) diameter column was packed to a depth of 1.5 m (5 ft) with a well-aggregated Oxisol soil (Lahaina series). A constant head was maintained by a modified Mariotte bottle during the application of effluent. Percolate was sampled through ports at 7 depths as well as from a bottom drain.

When effluent was continuously ponded on the surface: (1) percolate rate decreased with time, (2) ammonium ions were adsorbed, (3) nitrification was suppressed, (4) denitrification occurred, and (5) the denitrification biological community required more than 2 days to develop.

When effluent application was stopped after 2 days and aerobic conditions developed, nitrification was very active within 5 days.

The solute breakthrough curve appeared well in advance of 1 pore volume and was highly skewed with an extended tail.