Phosphorus Renovation of Wastewater by Overland Flow Land Application

摘要

A study was set up to monitor an operating overland flow wastewater system on soils derived from clayey coastal plain sediments. Three treatments were imposed on the Reed Canarygrass (Phalaris canarlensis) cover: cut 4 times per year and leave residue; cut 4 times and harvest residue; and cut 1 time and leave residue. Effluent was sampled at 6, 12, 18, and 27 m from the point of application as well as from final collection weirs and directly from spray nozzles. Inflow and outflow rates were monitored. Samples were collected on 8 dates at the beginning and end of each of 4 spray cycles consisting of 4-6 weeks of continuous spraying followed by a rest period of 4-6 weeks. Levels of total P in the applied effluent were low (1.5 mg/l) but application rates were high (15 to 23 cm/wk). The cutting treatments had no significant effect on P removal.