Bioclogging alleviation for constructed wetland based on the interaction among biofilm growth and hydrodynamics

Abstract

Bioclogging is the most crucial operation problem of the constructed wetlands, which reduce its removal e ciency and life span. A strategy through properly increasing hydraulic loading is proposed in this study to alleviate the bioclogging for CWs. The two-dimensional porous media ow cell (2D PMFC) test indicated that a quadratic correlation was found between local bio lms growth rate and the near-wall Reynolds number (r > 0.765, p < 0.05). The bio lm growth rate declined with the ow rate when Re exceeded 6. It was also found that the higher owrate (6 mL/min) lead to the homogeneous bio lm and velocity distribution in the PFMC. The column test indicated that the highest hydraulic loading (9.2 cm/h) produced the smallest decrease in hydraulic conductivity, which was 80 times more than that of low hydraulic load (3.0 cm/h) at the end (40 days) of experiment. Moreover, the relatively homogenized distribution of bio lm was found along the column with the highest hydraulic loading, which con rmed that the proper increase in hydraulic loading can alleviate bioclogging.