Combined pollution of heavy metals and polycyclic aromatic hydrocarbons in non-ferrous metal smelting wastewater treatment plant: Distribution profiles, removal efficiency, and ecological risks to receiving river

Combined pollution status of heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) from nonferrous metal smelting (NFMS) industry is crucial but has not been explored. Herein, the co-distribution of HMs and PAHs in a NFMS wastewater treatment plant and the impacts on the receiving river were investigated. Cu, As, and Ni were found to be the characteristic HMs, while Acenaphthylene was the characteristic PAHs in the NFMS wastewater. The removal of HMs and PAHs in wastewater showed a strong positive correlation (R-2 > 0.84, p <0.05) with removal efficiency of 90.7 % and 94.1 %, respectively. It was estimated 547.5 kg HMs and 13.3 kg PAHs were discharged into the receiving river annually. The average concentration of HMs and PAHs in downstream was respective 1.6 and 2.7 times higher than that in upstream, and the sites near discharge outlet had significant spatial autocorrelation (p < 0.05), suggesting the discharge of NFMS wastewater had significantly influenced the receiving river. Aquatic organisms were posed to moderate chronic ecological risk (RQC > 0.1) and surrounding residents were posed to probable carcinogenic risk (TCR > 10- 5). This work provides new insights into understanding the combined pollution and corresponding ecological risks from key industrial sectors globally.