#$%^&*AU2018204275A120180705.pdf#####ABSTRACT A method and device to treat liquid to reduce the amount of microorganisms in the liquid to a preselected level and/or to mitigate the growth of microorganisms are disclosed. Utilizing the method or device, liquid product is sprayed into a cavity of a reactor using a nozzle that produces a flat spray to provide means for efficient heating and treatment of the liquid.