The present disclosure relates to a system and process for cultivation of microalgae to produce algal biomass for production of environmentally friendly bioenergy. a novel approach leverages unused waste storage spaces for microalgae cultivation, facilitating the removal of radioiodine i-131 by growing microalgae in decay tanks. these tanks, which contain human excreta and radionuclide wastewater from thyroid cancer patients undergoing high dose radiation iodine treatment (hdrit), enable microalgae to absorb radioiodine. subsequently, the microalgae, treated with polyethylene glycol (peg), are processed into biogas, biofuels and bioelectricity. it is a new and innovative method and system of algae power cleanup of radioactive sludge to bioenergy.