Low energy nitrogen removal wetland technology

A method for nitrogen removal in wetlands comprising:

• receiving drainage inflow at a first column with the drainage flowing vertically within the first column, the first column filled with a first plurality of layers of filter media including rock media with ammonia adsorption capacity;
• receiving drainage from the first column at a mid-level reservoir;
• receiving drainage from the mid-level reservoir at a second column with the drainage flowing vertically within the second column, the second column filled with a second plurality of layers of filter media;
• and
• receiving discharge from the second column at a lower level reservoir, whereby nitrogen is removed from the effluent by the adsorption of ammonia, and wherein the first plurality of layers of filter media have ammonia adsorption capacity greater than 25 g ammonia N per cubic meter.