Effects of magnetic field on activity of activated sludge in wastewater treatment

In this study, the effects of magnetic field on activity of activated sludg e in wastewater treatment were investigated in a batch reactor system conta ining synthetic wastewater. The medium pH and the direct current (DC) magne tic field strength were changed in the ranges of 6.0 to 8.5 and 8.9 to 46.6 mT, respectively. Experiments were also conducted operating at pulsed DC a nd alternating current. The changes in the substrate (i.e. glucose) and mic roorganism concentrations were followed. The highest substrate removal and microorganisms growth rates were observed at pH 7.5. The difference between the substrate removal rates of experiments performed with magnetic field a nd without it was the maximum at this pH, which was about 44%. The substrat e removal rate was first increased by increasing the magnetic field strengt h, and reached the maximum at 17.8 mT, and decreased with further increase. Application of pulsed DC magnetic field did not change significantly the a ctivity of system, hereas using alternating current magnetic field instead of DC form even caused slight decrease in the activity. (C) 2000 Elsevier S cience Inc. All rights reserved.