Phosphorus removal in overland flow system for domestic wastewater treatment

摘要

> face="verdana" size="2">In order to evaluate the overland flow treatment efficiency for removing phosphorus (P) at different application rates: 0.24, 0.36 and 0.48 m3 h-1 m-1 of domestic wastewater, in flow slopes with a down-slope grade of 2%, an experiment was developed in the experimental area of the Agricultural Engineering Department of the Federal University of Viçosa. For the biomass production the 'coastcross' bermudagrass Cynodon dactylon was used. The highest removal rates for samples collected at 8 m from the beginning of the borders occurred for the application rate of 0.24 m3 h-1 m-1: 47.46% for total-P; 47.45% for total dissolved-P; 42.60% for inorganic dissolved-P; and 85.12% for organic dissolved-P. However, for total suspended-P, the highest removal rate (55.65%) occurred for the application rate of 0.36 m3 h-1 m-1. Soils samples were collected in two layers at 1 m from upper end: L1 (0 to 10 cm) and L2 (50 to 60 cm). A decrease in P for both layers for the treatments with 0.24 and 0.48 m3 h-1 m-1 of application rate was detected. In an opposite way, the amount of P for the treatment with 0.36 m3 h-1 m-1 increased. The treatment with 0.36 m3 h-1 m-1 of application rate, in 137 days, presented the highest values of P removals by the 'coastcross' bermudagrass.