Antimicrobial effects of pulsed electromagnetic fields from commercially available water treatment devices – controlled studies under static and flow conditions

Abstract

BACKGROUND: Pulsed-electromagnetic field (PEMF) devices are marketed and utilized for the non-chemical management of biofouling, with little scientific validation of their effectiveness. Proof-of-principle studies were carried out previously to systematically investigate the effect of two such commercial devices on the culturability of bacteria under controlled static (i.e. non-flowing) conditions and anti-microbial effects were demonstrated. However, such effects were small and an expanded investigation, using these devices and including the effect of flow, was deemed necessary. RESULTS: The effect of the electromagnetic fields generated by the same two commercial devices on the bacterial culturability of Escherichia coli and Pseudomonas fluorescens under flow conditions has been contrasted with previous static results. It has been found that the effectiveness of PEMF exposure depends on waveform, extent of flow, type of bacteria and PEMF exposure duration. CONCLUSION: Both stimulatory and inhibitory effects are observed that are uniquely dependent upon device type (i.e. a range of parameters including waveform), species of microorganism, presence and degree of flow and PEMF exposure time. For both devices and both microorganisms, stimulatory effects are uniformly observed for one device under static conditions and inhibitory effects are uniformly observed for the other device at low flow and for the former at high flow. © 2017 Society of Chemical Industry.