NOVELTY - A system comprises a tank (a), mixing device (b), device (c) for exposing the reaction mixture to light, a source of carbon dioxide, a device (d) connected to the source of CO2 gas for introducing CO2 into the reaction mixture and a device (e) for separating algae from the reaction mixture to produce remediated aqueous solution.    USE - The system is useful for removal of a contaminant (e.g. uranium, trans-uranium element, cobalt, chromium) from an aqueous solution (preferably water) (claimed).    ADVANTAGE - The system utilizes photosynthetic algae with less efforts for large scale removal of contaminants, as well as daughter products of uranium decay, other heavy metals and any trans-uranium species in aqueous solution (elements with atomic numbers greater than that of uranium) from the aqueous solution. The removal of contaminants from solution by algae is largely irreversible process. The system is cost-effective as photosynthetic algae are relatively simple and cost-effective to grow and maintain.    DETAILED DESCRIPTION - A system for removal of a contaminant from an aqueous solution containing the contaminant, utilizing photosynthetic algae that interacts with the contaminant to remove it from the aqueous solution, comprises a tank (a), mixing device (b), device (c) for exposing the reaction mixture to light, a source of carbon dioxide, a device (d) connected to the source of CO2 gas for introducing CO2 into the reaction mixture and a device (e) for separating algae. (a) Has at least two side walls and a floor for containing a reaction mixture. (a) Is open on its top side for exposure of the reaction mixture to light and air; and has an inlet for introducing fresh reaction mixture into the tank and an outlet spaced apart from the outlet pipe, for withdrawing reaction mixture which includes a quantity of aqueous solution with the contaminant and a quantity of photosynthetic algae that interacts with at least a portion of the contaminant to remove the contaminant from the aqueous solution while the reaction mixture is contained within the tank. (b) Is positioned for turning and operable to turn in the reaction mixture, to expose at least a portion of photosynthetic algae contained in the reaction mixture to light and air. (e) Separates algae from the reaction mixture to produce remediated aqueous solution; and connected to the outlet pipe.    An INDEPENDENT CLAIM is also included for a removal of uranium from an aqueous solution, involving selecting a photosynthetic algae for removal of uranium from the aqueous solution; introducing a first quantity of photosynthetic algae into a reactor and the aqueous solution into the reactor; mixing the first quantity of aqueous solution and the photosynthetic algae to form a reaction mixture; injecting CO2 gas into the reaction mixture; directing light onto at least a portion of the reaction mixture; continuing the mixing, injecting and directing light steps for a specified period, to attain desired growth of the algae and removal of uranium from the aqueous solution; removing a first portion of the reaction mixture from the reactor through an outlet in the reactor; and following the step of removing a portion of the reaction mixture, filtering the reaction mixture to remove photosynthetic algae for producing remediated aqueous solution.