Evaluation of the fertiliser replacement value of phosphorus-saturated filter media

V. Arenas-Montaño,B. Moore,M.G. Healy,O. Fenton

doi:10.1016/j.jclepro.2021.125943

Abstract

The use of filter media to adsorb phosphorus (P) from nutrient-rich waters is an effective, simple and low-cost method to recover and reuse P as an inorganic fertiliser replacement. Although it is assumed that the saturated filter media can be applied to cropland as a safe fertiliser replacement, there is presently a lack of information on the fertiliser replacement value (FRV) of such products and their negative effects on plants and soil. Therefore, the aims of this paper were to evaluate the (1) P removal capacity and plant response to soil application of waste media from three sectors (industry, agriculture, and construction and demolition), and natural and synthetic materials (2) potentially confounding risks arising from the reuse of media as a fertiliser replacement, and (3) factors affecting their fertilising efficiency once applied to soil. The predominant factors affecting the FRV of P-saturated media were their adsorption capacity and chemical composition, soil pH, and composition of water used for saturation. Some measures to overcome the negative impacts of the land application of P-saturated media include selecting the most appropriate soil-filter material combinations, the use of P solubilising microorganisms, and mixing with manure before land application. Despite confounding factors and a lack of information on the performance of some media under comparable study conditions, this study found that there is a significant potential for P-saturated filter media to partially replace the use of P mineral fertilisers and aid in the attainment of a “circular economy” in agriculture.

Highlights

The recovery and reuse of phosphorus (P) is a main requirement towards a circular bioeconomy (Jarvie et al, 2019), which aims at safeguarding future rock phosphate resources and achieving planetary P sustainability goals (Withers et al, 2015; Carraresi et al, 2018)
Despite confounding factors and a lack of information on the performance of some media under comparable study conditions, this study found that there is a significant potential for P-saturated filter media to partially replace the use of P mineral fertilisers and aid in the attainment of a “circular economy” in agriculture. 36 Keywords: Fertiliser replacement value; filter media; phosphorus; circular economy; waste management; adsorption. 39 1
These factors have been grouped into four classifications: adsorption capacity of the media, chemical composition of the media, soil pH, and composition of water used for saturation

Summary

Introduction

The recovery and reuse of phosphorus (P) is a main requirement towards a circular bioeconomy (Jarvie et al, 2019), which aims at safeguarding future rock phosphate resources and achieving planetary P sustainability goals (Withers et al, 2015; Carraresi et al, 2018). Some studies mention their suitability as P fertilisers based on their P concentration post sorption or after desorption tests (Huang et al, 2019; Jellali et al, 2011; Liu et al, 2019; Shepherd et al, 2016), but relatively few studies have evaluated their FRV in pot or field agronomical studies (Tables 2 to 6) Natural materials, such as sand and limestone, industrial waste materials, such as water treatment residuals, blast furnace slag and steel slag, and synthetic materials, such as layered double hydroxides, have been examined for their P adsorption capacity and for plant and soil response to the land application P-loaded filter media. Further economic and environmental studies are needed to justify the production of modified biochars for P removal and recycling to soil, as well as field studies comparing it to a mineral fertiliser for plant growth

Other materials with a potential as a P fertiliser

Other engineered materials

Findings

Conclusion