Electrochemical pH control and carbon supply for microalgae cultivation

Abstract

This study suggests a new water electrolysis-based microalgae cultivation system, which is capable of both pH control and the continuous supply of carbon source for bicarbonate-based microalgae cultivation. Daily basis running of a water electrolytic cell could effectively lower the pH of an algal culture medium within 6 to 90 min depending on the applied voltage, and at the same time, approximately 100–150 mg L−1 of carbon could be successfully supplemented into the anodic algal culture solution. Interestingly, the resulting algal biomass productivity reached the same final biomass concentration of 1.67 g L−1 regardless of the applied voltage and the concentration of catholyte; moreover, the applied voltage of 3–6 V did not affect the viability or lipid productivity of algal cells. The present study conclusively demonstrated that productive and convenient bicarbonate-based cultivation of microalgae is indeed possible when coupled with the water electrolysis-based electrochemical CO2 absorption process.