Behavior of Microorganisms from Wastewater Treatments in Extremely Low-Frequency Electric Field

Abstract

The paper presents the research results regarding the metabolism of microorganisms from domestic wastewater treatment-activated sludge. The research approached this issue by dielectric spectroscopy measurements, chemical analyses, and specific microbiological techniques. In addition, the influence of extremely low-frequency (ELF) electric fields (1÷500 Hz) on microbial metabolism was studied. Four representative frequencies have been identified: 49.9, 99.9, 130.8, and 150.4 Hz using dielectric spectroscopy applied to the investigated samples. Also, dielectric loss and conductivity evolutions showed significant discontinuities, indicating oscillation/resonance phenomena in the investigated biomass, unlike the sterilized sludge samples (obtained either by boiling or electrically, applying a voltage that creates a 100 V/m electric field strength on the sample), which did not show discontinuities; instead, the values of tgδ and σ were approx. 5-6 times larger. Chemical and microbiological tests have shown that the metabolism, growth, and multiplication of microorganisms in activated sludge are significantly increased after exposure to 4-6 V/m electric field strength of 50 Hz. The research may continue by developing equipment and a bioelectrotechnological process to significantly increase the efficiency of wastewater treatment plants.