Displacement of Br− and P22 in a Wetland Environment

Abstract

Relative displacement of bromide (Br−) and coliphage P22 was analyzed in surface water and vadose zone solution from a 3-ha surface flow constructed wetland. In the vadose zone, water samples at 0.3-, 0.76-, 1.5-, and 3-m depth were collected to quantify Br− and P22 simultaneously added into the wetland influent for a transport study. When P22 was detected, Br− arrived earlier to the monitoring depths than the phage suggesting that preferential flow facilitated P22 displacement in the vadose zone. Concentrations for both tracers indicated that bacteriophage removal through the vadose zone profile was exceeding 99.21 % of the peak concentration observed in surface water samples. For transport parameter estimation, the temporal moment method (MOM) was used to calculate convective velocity (v) and longitudinal dispersion coefficient (D) from the outlet Br− breakthrough curve. The transport parameters were estimated to be 55.7 m day−1 and 1652 m2 day−1 for v and D, respectively. For P22 simulation, a first-order removal coefficient of 0.3 day−1 (R 2 = 0.943) was assessed. The observed results suggest that this method can be applied for solute transport simulation in constructed wetlands.