Sorption of microconstituents onto primary sludge

The presence of microconstituents (MCs) in the environment has become an emerging concern to scientists and engineers. Sorption is one of the important removal mechanisms for MCs in wastewater treatment plants (WWTPs) since there is significant sludge production. The purpose of this study is to explore sorption kinetics and isotherms of MCs onto primary sludge. Three MCs, bisphenol-A (BPA), 17-α-ethinylestradiol (EE2) and triclosan (TCS), were chosen for this study. They are hydrophobic and have low vapor pressure, which makes sorption a potential removal mechanism. Both sorption kinetics and isotherm experiments were conducted using primary sludge collected from a local municipal WWTP. The time to equilibrium was around 7 h for all chosen MCs. A pseudo second-order rate model was better at describing the sorption rate than a pseudo first-order rate model. Linear sorption isotherm models were found to fit the experimental data, and the solid-liquid partitioning coefficients for BPA, EE2 and TCS were 81, 728 and 6,407 L/kg.