A Review of Phosphorus Removal Structures: How to Assess and Compare Their Performance

Abstract

Controlling dissolved phosphorus (P) losses to surface waters is challenging as most conservation practices are only effective at preventing particulate P losses. As a result, P removal structures were developed to filter dissolved P from drainage water before reaching a water body. While many P removal structures with different P sorption materials (PSMs) have been constructed over the past two decades, there remains a need to evaluate their performances and compare on a normalized basis. The purpose of this review was to compile performance data of pilot and field-scale P removal structures and present techniques for normalization and comparison. Over 40 studies were normalized by expressing cumulative P removal as a function of cumulative P loading to the contained PSM. Results were further analyzed as a function of retention time (RT), inflow P concentration, and type of PSM. Structures treating wastewater were generally more efficient than non-point drainage water due to higher RT and inflow P concentrations. For Ca-rich PSMs, including slag, increased RT allowed for greater P removal. Among structures with low RT and inflow P concentrations common to non-point drainage, Fe-based materials had an overall higher cumulative removal efficiency compared to non-slag and slag materials.

Phosphorus Solubilizing and Releasing Bacteria Screening from the Rhizosphere in a Natural Wetland

“…Much research is concerned with the effects of P removal by plants in wetlands [1,5,6], especially with the control of non-point source pollution [7]. However, plants can only absorb P in dissolved forms such as the free orthophosphate ions, H 2 PO 4 − and HPO 4 2− [8], while the available P in natural soil can be easily converted into insoluble complexes such as iron and aluminum hydrous oxides, crystalline and amorphous aluminum silicate, and calcium carbonate [9]. P can be dissolved by several mechanisms including Fe reduction [10], Ca removal and ligand exchange.…”

Phosphorus and the Chesapeake Bay: Lingering Issues and Emerging Concerns for Agriculture

“…Monitoring and mitigation of stormwater from such developments should be treated as a priority water quality concern as well as a priority research topic. Practices such as the use of P sorbing materials in runoff detention/retention basins or P‐rich soils around poultry houses all show potential (Buda et al, 2012 Bryant et al, 2012; Penn et al, 2017). …”

Increasing the Effectiveness and Adoption of Agricultural Phosphorus Management Strategies to Minimize Water Quality Impairment

“…Water‐control structures can reduce SRP loss from fields by affecting hydrology (Evans et al, 1991; Penn et al, 2017; Zhang et al, 2017). Evans et al (1991) found a net reduction in edge‐of‐field total P losses of 35% under controlled drainage.…”

“…Phosphorus sorbing materials offer the potential to trap edge‐of‐field P losses when used in off‐site stormwater treatment structures. Off‐site structures that contained PSMs were found by multiple researchers (Penn et al, 2017; Qin and Shober, 2018) to be effective at removing soluble P (and to some extent particulate P) from runoff. Additionally, several researchers have demonstrated that PSMs in drain tiles may be useful in reducing leached P (King et al, 2016; McDowell et al, 2008).…”

“…Many factors affect P reduction by off‐site structures, including structure material, resident time, and influent concentration. In their review, Penn et al (2017) determined that Fe‐containing PSMs performed better (∼35%) at reducing P concentrations in agricultural runoff than did nonslag and slag materials containing Al (∼25%). However, to be cost‐efficient, these structures must carefully balance the P adsorptive capacity of the material, as well as the flow dynamics of the system (i.e., containment structure or buffered filter).…”