*3.1.2 Phosphorous removal*

Phosphorus removal is primarily through sorption by clay, and typically will reach a saturation point after which phosphorus can leach back into the water it should be treating [23], and upon reaching this point, wetland clay materials should be replaced. Additional sorption can be achieved via decomposed plant matter [23]. Studies on the Prado wetlands in California USA suggest that constructed wetlands have, on average, 40–50% TP removal [22].
