Unveiling typical emerging contaminants in wastewater from printed circuit board industries in South China.

China has gradually become the core producer and consumer of the global printed circuit board industry. The study systematically investigated the environmental behavior of three key functional chemical substances in the whole process of a printed circuit board industry in South China from the production source. Through tracing the environmental media in the industry, it was found that per- and polyfluoroalkyl substances (PFASs), used as surfactants, and polybrominated diphenyl ethers (PBDEs) and organophosphoric acid esters (OPEs), used as flame retardants, exhibited unique pollution characteristics. The concentrations of PFASs, PBDEs and OPEs in the wastewater were 0.65-34.82 ng/L, not detected (N.D.)-106.38 ng/L, and 75.27-7999.15 ng/L, respectively. The PFAS, PBDE, and OPE concentrations in the sludge were 0.13-1.48 ng/g dw, N.D.-0.98 ng/g dw, and 31.95-519.40 ng/g dw, respectively. It revealed that although OPEs dominated the total pollutants, a good removal efficiency and low ecological risk were demonstrated in the wastewater treatment process, and only tris (2-chloroethyl) phosphate showed a relatively weak removal effect. In contrast, 2,2',4,4',5,5'-Hexabromodiphenyl ether showed significant aquatic ecological risk (maximum risk quotient up to 20) despite its low concentration. In addition, an intrinsic links between different types of industries, annual production capacity, and annual emissions of emerging contaminants were revealed. This study not only provides a scientific basis for the development of differentiated pollution prevention and control strategies for industries, but also has important guiding significance for the realization of green manufacturing and sustainable development.