Abstract: A cooling system is provided having a first heat exchanger for heating a cooling liquid, a second heat exchanger, which preferably comprises an evaporator, for cooling the cooling liquid, and a pump for guiding the cooling liquid through the first and second heat exchanger. The system includes a pellet reactor through which cooling liquid is fed, so as to remove impurities from the cooling liquid by grafting the impurities onto graft material in the pellet reactor. A method is also provided for using such a cooling system. An advantage of the system is especially that calcium salts can be grafted onto the graft material, as a result of which the concentration factor of the cooling system can be increased significantly.