if something is expelled in a process, then that something is a waste product of that process
vomit is expulsion. purification_process is removing_from_stuff. purge is removal. purge is not removal. excreting is not bodily_function_event. refining is not process_of_removing_unwanted_material. vomit is not expulsion. excreting is not emission_of_object. purification_process is not removing_from_stuff. excreting is bodily_function_event.