Copper removal from semiconductor CMP wastewater in the presence of nano-SiO2 through biosorption

Copper-bearing wastewater from chemical mechanical planarization (CMP) is a typical semiconductor development byproduct. How to effectively treat Cu2+ in the CMP wastewater is a great concern in the microchip manufacturing industry. In this study, we investigated the potential for the microbial removal of Cu2+ by a multiple heavy metal-resistant bacterium Cupriavidus gilardii CR3. The environmental factors, including pH, nano-SiO2, ionic strengths, and initial concentrations of Cu2+, and adsorption times on the bioremoval of Cu2+ in CMP wastewater were optimized. Under optimal condition, the maximum biosorption capacity for Cu2+ was 18.25 mg g−1 and the bioremoval rate was 95.2%. The Freundlich model is described well for the biosorption of Cu2+ in CMP wastewater in the presence of nano-SiO2 (R2 = 0.99). The biosorption process obeyed the pseudo-second-order kinetic equation (R2 > 0.99). In the column experiment, the advection–dispersion–retention model fitted the breakthrough curve of all experiments well (R2 > 0.95). The attachment coefficient in the sand matrix coated by CR3 biofilm was 2.24–2.80 times as that in clean sand. Overall, C. gilardii CR3 is a promising candidate to remove Cu2+ from CMP wastewater. Nano-SiO2 in CMP wastewater did not inhibit the bioremoval of Cu2+ but showed a slight promotion effect instead.