Nitrogen enters the wastewater in various forms such as ammonia, organic nitrogen, nitrite and nitrate. The nitrate is usable by plants as a food source.
Natural systems remove phosphorus through absorption onto soil particles.
Emergent plants may also be able to extract phosphorus from wastewaters. The cooperative growth of plants, bacteria, fungi, and other microorganisms play a key role in natural wastewater treatment. Once microorganisms are established on plant roots they form a symbiotic relationship with the plants, degrading and removing organic chemicals from wastewater surrounding the root systems. The microorganisms degrade the organics, producing metabolites which they and the plants utilize along with nitrogen, phosphorus and other minerals as a food source. By using each other's waste products as a food source, organics are rapidly removed.