metabolic waste nitrogenous wastes metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste nitrogen excretion nitrogenous wastes metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste metabolic waste Ammonia Metabolic waste nitrogenous wastes getting rid of nitrogen metabolic wastes metabolic waste metabolic waste en.wikipedia.org metabolic waste nitrogenous wastes