Prior to starting the experiments, the MFCs were matured for 14 days using a solution composed of sludge supplemented with 100mM acetate as the substrate. At this starting point, the cathode chamber was completely empty and dry, in order for catholyte to be actively synthesised, as a direct result of the MFC operation. During this process, the MFCs generated sufficient amounts of catholyte to be subsequently usedfor microalgae lysis.