when he returned to england, fowler suggested to edward ardern, his chief chemist, and william lockett, the chief research assistant, that they research ways to reduce the growth of algae. they lowered the light levels, as sunlight often triggered the growth of algae, and kept the precipitant floc, which contained many bacteria, from one experiment to the next. each subsequent experiment was more successful than the last, as the sludge showed better clarifying properties as it got older. ardern and lockett had discovered the activated sludge process, which was soon being used worldwide. the research was carried out at manchester university, and fowler presented the results at the grand hotel in manchester in april and november 1914.