Clean Technology 2010
J. Smeraldi, G. Rajagopalan, W.J. Cooper, T. Hosseini, D. Rosso
University of California, Irvine, US
nanocopper, wastewater, activated sludge, adsorption
Objective of this study is to compare the fate, removal and inhibitory effects of nanocopper (oxide) with ionic copper in activated sludge. Impacts of functionalization (complexation) of nanocopper as well as the mechanism of nanocopper removal (precipitation, aggregation, biosorption) were also investigated. Adsorption isotherm studies were performed with unfiltered and filtered (0.45 µm) activated sludge, to estimate the copper removed by chemical precipitation or physical aggregation. The difference in these two studies yielded the copper removed by biosorption. Nanocopper and copper ion were analyzed by ICP-MS, particle size distribution and count of nanomaterials were evaluated using dynamic light scattering, inhibitory effects of nanocopper to activated sludge bacteria were evaluated through MPN studies. Results from the isotherm studies indicated that nanocopper (94-96%) was removed more effectively than copper ion (55-85%). Nearly 80 % of nanocopper was removed by aggregation/settling and 15% through biosorption. Nearly 60 % of copper ion was removed by chemical precipitation and 15% through biosorption. MPN tests indicated that at 10 mg/l concentration both nanocopper and copper ions were inhibitory to all bacteria. Nanocopper was less inhibitory than copper ions to bacteria, was more effectively removed and showed lower toxicity under the experimental conditions used.