Abstract: A waste water treatment system is provided that includes a basin for holding water; nitrifying and denitrifying bacteria; macroalgae; and a biobed having a at least one layer and being constructed of materials selected to provide sufficient level of pH for enabling bacterial growth. In the biobed de-nitrification and nitrification bacterial processes are separated. Oxygen produced by algae is used by the nitrifying bacteria. Water is provided continuously to the biobed at an inlet and exits the system downstream after having gone through the biobed. The system may be used with waste water in water treatment plants, domestic waste water (sewage), waste water from diverse industries, drain water from waste deposits, runoff water from roads, water waste treatment and recycling plants, agricultural and farm land and surrounding land of populated areas. The algae and bacteria are combined for symbiotic remediation of water that may be flexibly controlled to adapt to a broad range of applications.