The characteristic of electrode of degradation of bio-electrochemical system based on in-situ ultrasonic monitoring: Biofilm and ion precipitation

Highlights: • Ultrasound was used to in-situ monitor the fouling layer of electrode surface • The deposition layer gradually invaded the biofilm from the electrode interface. • An in-situ cleaning method for contaminated cathode was proposed. Electrode interface behavior is a decisive factor affecting the performance of bio-electrochemical systems, and traditional monitoring methods cannot provide real-time feedback. Therefore, in situ ultrasonic monitoring was performed to continuously monitor the formation process of electroactive biofilm and salt precipitation on the cathode surface. The results showed that biofilm was attached to the cathode surface first. Then, Ca²⁺ and Mg²⁺ precipitation gradually invaded the biofilm and accumulated between the cathode and the biofilm. The electrochemical performance of the biofilm adhesion and initial ion invasion process was improved. However, the electrochemical performance of the precipitation layer was decreased, while the operation time increases. In this paper, based on the air cathode scaling analyzing a new method for monitoring the electrode interface of bio-electrochemical system was provided, and the performance was recovered by using reverse electric field.