Influence of biofilms on the adsorption behavior of nine organic emerging contaminants on microplastics in field-laboratory exposure experiments.

Microplastics (MPs) are ubiquitous in aquatic environments, which are important carriers of emerging contaminants (ECs). Biofilms can be attached to the surface of MPs in a natural aquatic environment, which may influence chemical adsorption; however, knowledge of its impact is still limited. This study investigated the effect of biofilms on MPs on the adsorption of ECs through field-laboratory exposure experiments. Three types of MPs were naturally colonized with biofilms in lake. Then, biofilm-absent/biofilm-attached MPs were exposed to nine EC solutions at a concentration of 8 µg/L of each compound in laboratory. Most compounds exhibited 3.8 times lower concentrations on biofilm-attached MPs than on biofilm-absent MPs; only a few compounds showed enhanced adsorption. Pseudo-equilibrium was achieved within 72 h based on adsorption kinetics, implying fast adsorption of ECs on biofilm-attached MPs. The partition coefficients (Kd) for biofilm-attached MPs were 0.14 (diclofenac) to 535 (miconazole) L/kg and were positively correlated with octanol/water partition coefficients (Kow). This indicated that chemical properties (such as Kow) of the compounds determined their final adsorption amounts on MPs, although these were influenced by the presence of the biofilm. Hence, multiple influencing factors should be considered when evaluating the carrier potential of MPs for ECs in aquatic environments.

Profile and removal of bisphenol analogues in hospital wastewater, landfill leachate, and municipal wastewater in South China.

The presence of bisphenol analogues (BPs) in wastewater can have adverse effects to organisms in the environment. However, knowledge of the wastewater sources, such as hospitals and landfills, as well as the removal of BPs are still limited. Fifteen BPs were investigated in hospital, landfills, and municipal wastewater treatment plants (WWTPs) in South China. Eleven BPs were detected in various source wastewaters, and bisphenol A (BPA) is generally the dominant pollutant. In 4 hospitals, the total concentrations of BPs (∑BPs) in hospital wastewater and treated wastewater ranged from 122 to 1040 ng/L. In the landfill, ∑BPs in leachate and treated leachates were 32,130 and 145 ng/L, respectively. In 5 municipal WWTPs, ∑BPs was up to 17,200 ng/L in influents, 502 ng/L in effluents, and 291 ng/g in sludges. The modified A2/O process exhibited best removal profile for BPs, while the UNITANK process had no advantages. The annual mass load estimates of hospital treated wastewater, landfill treated leachate, and WWTP effluents in Guangdong Province, South China, were 630, 9.46, and 4697 kg/y, respectively. The risk quotient values in source effluents revealed low to medium estrogenic risks to receiving rivers. Control measures should be applied to further remove BPs not only from WWTP effluents but also from other sources.