Removing dissolved phosphorus from drainage ditch water with phosphorus sorbing materials

The loss of nutrients, particularly phosphorus (P), in agricultural drainage waters is a priority conservation concern. Open drainage ditches concentrate runoff and therefore offer opportunities for capturing P in runoff from large areas of land. This paper provides an overview of the potential to use P sorbing materials in drainage ditches to sequester dissolved P from ditch water. We describe factors affecting the selection of P sorbing materials for use in treating ditch water and review several approaches to their application in ditches. In addition, experiential insight is provided with regard to developing and installing a P removal structure within a ditch that has high concentrations of dissolved P in flow. Preliminary data indicate that such structures have great promise in treating not only dissolved P in ditch flow, but also trace metals (arsenic, copper, nickel, zinc).