Effects of Cu~(2+) on biological process of wastewater treatment plant (WWTP) in electroplating industrial park

摘要

The construction of industrial clusters in China increases the possibility of treating heavy metals containing wastewater by biological treatment process. Those heavy metals which entered wastewater treatment systems will have a toxic impact on the bacteria. The effects of 0-10mgL(-1) Cu2+ on the performance of an anoxic/oxicmembrane bioreactor (A/O-MBR) process, which simulated the wastewater treatment process in a local surface processing industrial park, in treating electroplating mixed wastewater were investigated in this research. Under the experimental conditions (simulated the real influent scenario), COD removal efficiency and nitrification efficiency of the process were obviously inhibited by 5 and 3mgL(-1) Cu2+, respectively, while were severely inhibited by 10 and 5mgL(-1) Cu2+, respectively. Above 1mgL(-1) of Cu2+ would put negative effects on the activities of both autotrophic and heterotrophic bacteria, moreover, autotrophic bacteria were more sensitive to Cu2+ than heterotrophic bacteria. The synthesis of the extracellular polymeric substance (EPS) can be stimulated by 1mgL(-1) Cu2+ while inhibited at higher concentrations. The quantity of EPS was in direct proportion to that of proteins in the experiment indicated that proteins in EPS played a major role in protecting cells from the harm of heavy metals.