This review evaluates the use of filter materials (FMs) to reduce dissolved reactive phosphorus (DRP) losses from tile-drained agricultural catchments, a key source of phosphorus pollution in surface waters. It concludes that sorption-based retention, especially using iron- and aluminum-rich FMs, outperforms precipitation-based methods due to strong DRP binding, fast reaction times, and low desorption. Calcium- and magnesium-based FMs are effective only under favorable catchment conditions and require optimal reactivity. Hydraulic retention time is critical for FM performance, particularly for precipitation-dependent materials. Designing and managing FMs in alignment with catchment-specific flow variability and DRP levels is essential for sustained high retention, cost-effectiveness, and environmentally safe effluent discharge.
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