Nutrients — commonly nitrogen and phosphorus — are found in agricultural and home fertilizers and also are generated by livestock, industrial, and municipal systems. Nutrients are needed to sustain life, but too many nutrients in aquatic environments lead to the depletion of oxygen, potentially leading to poor water quality or “dead zones” that cannot sustain life. Wastewater treatment plant effluent is one of several sources of nutrients in the aquatic environment. Water resource recovery facilities can achieve very low nutrient levels from  can be achieved through advanced biological and chemical methods, but trade-offs exist between the nutrient removal and the chemicals and energy consumption it requires.