Effect of copper nanoparticles on biological wastewater treatment

Abstract

The widespread use of nanoparticles (Nps) inevitably leads to their release into the environment, in particular from wastewater treatment plants. During wastewater treatment, nanoparticles undergo aggregation, sedimentation and transformation, which may cause their concentration in effluents and the sludge. Activated sludge contains microorganisms that play an important role in the biological wastewater treatment process. Microorganisms in biological treatment processes may be exposed to nanoparticles that were agglomerated or adsorbed to extracellular polymers during treatment. The aim of the study was to determine the effect of copper nanoparticles (CuNPs) on wastewater treatment in the sequencing batch reactor (SBR) bioreactor. Analyses of total organic carbon (TOC), suspended solids, volatile suspended solids, pH and total copper were performed. Microbial obser-vations of activated sludge were performed and, on their basis, the Madonia sludge biotic index was evaluated. It was found that at a concentration of 3 mg/L CuNPs, the degree of wastewater treatment decreased from 92.17% to 71.9% (based on the TOC). CuNPs may negatively affect the activity of activated sludge in SBR reactors.