Successful use of electrochemical nitrate sensor for bioremediation monitoring in microalgal cultures

Abstract

In this work, a copper-based electrochemical sensor, obtained using a single-side copper plate board commonly employed in printed circuit board technology, was proposed for the analysis of nitrate ions in microalgal cultures. The sensor with a three-electrodes configuration was fabricated by using a micro-milling machine. After the modification of the reference electrode with a silver/silver chloride paste and of the counter electrode with graphite ink, sensor performance was evaluated by assessing repeatability, reproducibility, stability, and selectivity using linear scan voltammetry to detect the reduction peak of nitrate ions. The produced sensor had a limit of detection of 5.2 ppm with a sensitivity of 0.776 μA ppm−1 and a relative standard deviation of 0.67 %. The sensor was then used to monitor the concentration of nitrates during the bioremediation by an indigenous microalgal culture in both synthetic and real wastewater. A linear correlation between the results obtained using both the standard ionic chromatography and the sensor was found (R2> 0.99). Thus, this work demonstrated the feasibility of using electrochemical sensors for real-time analysis in biological remediation processes. This potential application can be useful for optimizing microalgal use in wastewater treatment.