http://worldcat.org/entity/work/id/255726326

Overland flow treatment of wastewater interim report

Land application has been suggested as an effective, low-cost method for advanced treatment of wastewater from military reservation treatment plants. This study is being conducted to determine the mechanisms involved in wastewater treatment by overland flow so that operational feasibility, design, and performance criteria can be more accurately evaluated. A model 5 ft wide and 20 ft long was prepared with grass sod and a low-permeable Susquehanna clay to a 6-in. depth at a 2% slope. Secondary effluent from a model treatment plant was supplemented with 13.4 mg/l of nitrogen as ammonium nitrate and 0.2 mg/l of cadmium, copper, lead, manganese, nickel, and zinc to simulate average wastewater. The study was conducted for 12 weeks with effluent applied by flooding from the upper end of the slope at 0.5 in./day (6-hr periods) for 4 days per week. The wastewater was generally distributed into 20, 30, and 50% for subflow, evapotranspiration, and runoff, respectively. Analyses showed that 100, 95, 91, and 75% of the ammonium, nitrate, and organic nitrogen and phosphorus, respectively, were retained in the model. The loss of 25% of the applied phosphorus in runoff indicated a need for more surface contact, probably obtainable by increasing the model length. The subflow analyses showed excellent removal of nitrogen, phosphorus, and most heavy metals indicating effective removal mechanisms by the soil during the study period.

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