Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Circular Economy Model Through Phosphorus Recovery to Obtain Struvite from Sewage Sludge

Version 1 : Received: 26 April 2023 / Approved: 27 April 2023 / Online: 27 April 2023 (04:40:57 CEST)

A peer-reviewed article of this Preprint also exists.

Cañas, J.; Álvarez-Torrellas, S.; Hermana, B.; García, J. Phosphorus Recovery from Sewage Sludge as Struvite. Water 2023, 15, 2382. Cañas, J.; Álvarez-Torrellas, S.; Hermana, B.; García, J. Phosphorus Recovery from Sewage Sludge as Struvite. Water 2023, 15, 2382.

Abstract

Environmental legislation on waste management coupled with the potential for nutrients recovery are key factors encouraging the use of advanced treatment technologies to manage biosolids waste. In this context, phosphorus recovery from a sewage sludge treated by a wet oxidation process was carried out. High organic matter (up to 85% in COD) and Total Solids content (up to 75%) removal values were achieved at elevated temperature (up to 300 ºC) and pressure (up to 200 bar) conditions. The liquid and solid fractions found in oxidation process effluent contain amounts of phosphorus that can be recovered. This research aims to maximize its valorization in both liquid and solid fractions. In the liquid effluent, phosphorus was recovered (up to 90 mg P L-1) by chemical precipitation as struvite (MgNH4PO4∙6 H2O), a slow-release fertilizer. In this case, P recoveries greater than 95% were achieved. Also, the solid fraction, analyzed after filtration and drying (68 mg P gsolid-1), was treated by acid leaching, to achieve up to 60% phosphorus recovery. All phosphorus extracted was in orthophosphate form.

Keywords

Circular economy; phosphorus; struvite; valorization; wet oxidation.

Subject

Environmental and Earth Sciences, Water Science and Technology

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