Influence of a low-frequency magnetic field on the growth of microorganisms in activated sludge

Abstract

Activated sludge treatment systems for wastewater treatment are increasingly used worldwide, and their efficiencies in the removal of organic matter are high. However these depend on the growth and development of the microorganisms that compose it, therefore generating a stimulus that allows to increase the microbial growth to have an impact on the removal. One of the methods that are currently being researched to stimulate this growth is the use of low-frequency magnetic fields. Therefore, this article presents the response of different microorganisms contained in an activated sludge at magnetic field densities of 5, 10 and 20 mT in periods of time of 30, 60 and 120 minutes, finding that for magnetic fields of 10 mT for 60 minutes and 20 mT for 30 minutes there is an increase in the growth rate close to 68% in bacteria, while for fungi the greatest increase was found in the magnetic field of 5 mT during all exposure times close to 50%. On the other hand, there was also an inhibitory effect for bacteria and fungi in magnetic fields of 10 and 20 mT for different times.