Effect of low-impact technologies on urban runoff water treatment.

The impact of a bioretention cell on the treatment of urban runoff water (aeu) was evaluated. The cell was constructed with the following stratification of materials (from the base): 20% gravel, 40% gravel, hydrogel, 40% clinoptilolite, and succulent plants as cover. Real aeu was fed for 24 hours at constant rate to simulate 3.9 mm of precipitation. Samples were taken at the cell inlet and outlet to analyze dqo, N-NH4 +, N-NO2 -, N-NO3 -, PO43- (total and dissolved), Escherichia coli count and various metals (Al, Fe, Cu, Mn, Pb, Zn, Cr, Cd and Ni). To evaluate the effect of the cell on water quality, an index was proposed and calculated for the aeu before and after treatment. The system removed several of the contaminants evaluated: dqo (28.5%), N-NH4+ (84.3%), N-NO3 - (49.4%), total PO4 3- (94.8%), and dissolved PO43- (86.2%). Metals were removed with efficiencies ranging from 90% to 99%, with the exception of Ni (58.7%), while E. coli was removed at 100%.The quality index calculated for the treated water was considerably lower than the index of the input aeu, showing that the cell improved water quality.