Impact of phosphorus on the functional properties of extracellular polymeric substances recovered from sludge
Nouran T. Bahgat, Philipp Wilfert, Stephen J. Picken, Leo Sorin, Yuemei Lin, Leon Korving, Mark C.M. van Loosdrecht
Abstract
• Analogue to synthetic polymers, phosphorus influences EPS properties. • Leveraging P chemistry in EPS aims to enhance EPS industrial applications. • Phosphorus in sludge enables EPS engineering along the EPS extraction process. • Organic P in EPS increases with chemical phosphorylation along its extraction process. Extracellular Polymeric Substances (EPS) are ubiquitous in biological wastewater treatment (WWT) technologies like activated sludge systems, biofilm reactors, and granular sludge systems. EPS recovery from sludge potentially offers a high-value material for the industry. It can be utilized as a coating in slow-release fertilizers, as a bio-stimulant, as a binding agent in building materials, for the production of flame retarding materials, and more. P recovered within the extracted EPS is an intrinsic part of the recovered material that potentially influences its properties and industrial applications. P is present in EPS in different speciation (e.g., P esters, poly-P, ortho-P, etc.). Such P species are already intensively used in the chemical industry to enhance thermal stability, viscoelasticity, emulsification, water-holding capacity, and many other properties of some natural and petroleum-derived polymers. The translation of this knowledge to EPS is missing which prevents the full utilization of phosphorus in EPS. This knowledge could allow us to engineer EPS via phosphorus for specific target properties and applications. In this review, we discuss how P could affect EPS properties based on experiences from other industries and reflect on how these P species could be influenced during the EPS extraction process or in the WWTPs.