Concentrations and fate of parabens and their metabolites in two typical wastewater treatment plants in northeastern China.

Parabens are widely used in food, pharmaceuticals, and personal care products because they are excellent preservatives. Recently, the environmental fate of parabens has attracted attention owing to their similarity to some endocrine disrupters. Wastewater treatment plants (WWTPs) are both important sinks of parabens discharged from our daily activities and key pollution sources for the environment if the parabens are not completely removed. However, research in this area is scarce, especially in Asia. In this study, 6 commonly used parabens and 4 metabolites were analyzed in wastewater and sludge samples from two typical WWTPs with different treatment processes (the anaerobic-oxic (A/O) and cyclic activated sludge technology (CAST) treatment processes). The average concentrations of parabens in the A/O and CAST treatment processes were 1510 ng/L and 2180 ng/L, respectively, in the influent, and 70.5 ng/L and 19.7 ng/L, respectively, in the effluent. The paraben removal efficiencies in the A/O treatment process were between 56.8% and 100%, which is lower than the efficiencies for the CAST treatment process (97.7% to 100%). The average concentrations of metabolites in the A/O treatment process, which were much higher than paraben concentrations, were 35,200 ng/L in the influent, 334 ng/L in the effluent, and 146 ng/g in the sludge samples. The removal efficiencies for the 4 metabolites were >92% for the A/O treatment process. In total, for the A/O treatment process, 5.07 kg and 16.8 kg of parabens, and 24.4 kg and 16.0 kg of metabolites, were discharged into the environment annually via effluent and sludge, respectively. Overall, the results of this study indicate that the A/O and CAST treatment processes are both effective at removing parabens and their metabolites.

Removal characteristic of surfactants in typical industrial and domestic wastewater treatment plants in Northeast China.

Surfactants are widely used in household and industrial products for cleaning and/or solubilization in our daily life. Therefore, they are finally discharged into wastewater treatment plants (WWTPs), which may be the major point pollution source for environment if they were not completely removed during wastewater treatment. In this study, two typical industrial and domestic WWTPs with different wastewater treatment technologies were considered for the topic. Totally, two types of surfactants were analyzed in 24 h influent and each processing unit effluent. Four linear alkylbenzene sulfonates (LASs) with the alkyl chain from C10 to C13, and two benzalkonium chlorides (BACs) with the alkyl chain of C12 and C14 were selected as target compounds. The total concentrations of LASs in influent varied from 19.2 to 1889 µg/L and LAS-C11 and LAS-C12 were the predominant compounds with the concentration from 6.01 to 641 µg/L and 8.02-674 µg/L, respectively. The total concentrations of BACs were much lower than those of LASs, with the concentration ranging from 0.00935 to 1.85 µg/L. Significant positive correlations were observed between concentrations of LASs and BACs in influent, indicating their same and/or similar sources. Compared with the concentration of influent, the concentration of effluent was much lower, indicating the high removal efficiency by the two wastewater treatment processes. Biological treatment unit and cyclic activated sludge system were the main treatment units for the removing of surfactants, which suggested that these two types of surfactants can be easily degraded under aerobic condition. Seasonal variation indicated that the removal efficiencies of surfactants in autumn were a little higher than those in winter. The results of this study provided new insights into the environmental fate of surfactants in wastewater treatment system.