title: Phosphorus partitioning in co-dewatering biosolids and water treatment residuals.
abstract: Stabilization and dewatering methods for wastewater solids determine the concentration and nature of phosphorus (P) in biosolids and in-plant sidestreams recycled to the liquid treatment facility. Because water treatment residuals (WTR) exhibit strong immobilization of soluble P, this study evaluated the impact of co-dewatering WTR and biosolids on the P partitioning during dewatering and the environmental lability of biosolids-P measured by water-extractable P (WEP). Overall, P progressively partitioned into the water-insoluble particulate-bound form in dewatered cake with increasing blending ratio (BR) - defined as the dry mass ratio of WTR to biosolids. The reject water total P (TP) content from dewatering biosolids alone (250 mg L⁻¹) was reduced to 60 mg L⁻¹ for a BR = 1.5. Polymer addition resulted in statistically (α = 0.05) lower reject liquid TP, suggesting the cationic polyelectrolyte contributed to P binding. The WEP of the dewatered cake (∼20% solids) dropped from 2.36 g kg⁻¹ (biosolids only) to ∼0.14 g kg⁻¹ for BR = 1.5, meaning the P in land-applied co-processed cake is less susceptible to solubilization by surface runoff compared to unamended biosolids. Co-dewatering can reduce P in return flows and fix P in the dewatered solids in a form less prone to off-site migration following land application.
authors.affiliation: Agricultural and Biological Engineering Department, Penn State University, 249 Ag Engineering Building, University Park, PA 16802, USA E-mail: hae1@psu.edu.
authors.forename: Herschel A
authors.initials: HA
authors.lastname: Elliott
authors.affiliation: Atkins North America Inc., Calverton, MD, USA.
authors.forename: Malcolm
authors.initials: M
authors.lastname: Taylor
mesh_terms: D010758:Phosphorus / Q000302:isolation & purification*; D012722:Sewage; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D012722:Sewage; D014874:Water Pollutants, Chemical; D010758:Phosphorus