Novel bio-electro-Fenton process for the treatment of non-biodegradable pollutants. Salinity-gradient energy drove the bio-electro-Fenton process for azo dye removal. High removal efficiency was achieved at relatively higher azo dye concentration. Identified key factors affecting the azo dye degradation in the MREC-Fenton system. Completely removal of azo dye with low energy consumption in MREC-Fenton system.