Non-ohmic electrical fringe field selective to biofilm suitable for addressing biofouling in wastewater treatment

Abstract

The non-ohmic electrical fringe field has been shown to be a viable approach for addressing biofouling in wastewater treatment. Existing attached growth systems require periodic mechanical- or chemical-based maintenance or part replacement to regulate excessive biofilm formation. The proposed electrical approach uses a non-ohmic fringe field at a low voltage of 10 V and a low frequency of 100 kHz, where bacterial biofilm growth is noticeably reduced. The fringe field was generated by insulated interdigitated electrodes embedded below the surface on which the biofilm grew. Electric field simulation showed field strength of 15.2 and 12.3 V/cm at 0.05 and 1 mm from the surface, respectively, which are sufficient to reduce biofilm growth. As the biofilm grows, the fringe field passing through it becomes denser (hence, higher field strength) owing to the difference in relative permittivity. It selectively targeted biofilms in water. The optical density measurements showed that the presence of fringe field was able to reduce the biofilm by ∼10.1 % as compared to the control. Adenosine triphosphate measurements suggested that the effect of fringe field on bacterial viability was even more pronounced at ∼20.6 % reduction. This is an efficient approach with no moving parts suitable for uninterrupted biofilm growth regulation in wastewater treatment.