The project for sustainable water use in chemical, paper, textile and food industries
This report is a result of the project AquaFit4Use, a large-scale European research project cofinanced by the 7th framework programme of the European Union on water treatment technologies and processes. This report describes investigations devoted to studying the impact of Ag nanoparticles on biological processes in effluent treatment. The action of silver nanoparticles has been analysed using model systems for anaerobic and aerobic treatment processes. The impact of nanoscale silver on the respiratory activity of aerobic activated sludge was traced continuously by means of respirometric measurement. Industrial process media (effluents, activated sludge, pellet sludge) from a paper mill were used for the analyses. Furthermore, trials were conducted in lab-scale and on mile-site to study the action that surfacebonded Ag nanoparticles had on preventing slime formation. For this purpose, especially prepared steel plates were positioned in the splash zone of a paper machine and the coating of the surface compared once the exposure time has expired. The methods used are explained, the testing equipment is described. The results of the individual test series are presented both in tabular and graphical form. The results demonstrate that no impairment of effluent treatment processes is to be expected when Ag nanoparticles are used in the concentrations recommended by the manufacturer.