title: Characterization, Recovery Opportunities, and Valuation of Metals in Municipal Sludges from U.S. Wastewater Treatment Plants Nationwide.
abstract: U.S. sewage sludges were analyzed for 58 regulated and nonregulated elements by ICP-MS and electron microscopy to explore opportunities for removal and recovery. Sludge/water distribution coefficients (KD, L/kg dry weight) spanned 5 orders of magnitude, indicating significant metal accumulation in biosolids. Rare-earth elements and minor metals (Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) detected in sludges showed enrichment factors (EFs) near unity, suggesting dust or soils as likely dominant sources. In contrast, most platinum group elements (i.e., Ru, Rh, Pd, Pt) showed high EF and KD values, indicating anthropogenic sources. Numerous metallic and metal oxide colloids (<100-500 nm diameter) were detected; the morphology of abundant aggregates of primary particles measuring <100 nm provided clues to their origin. For a community of 1 million people, metals in biosolids were valued at up to US$13 million annually. A model incorporating a parameter (KD × EF × $Value) to capture the relative potential for economic value from biosolids revealed the identity of the 13 most lucrative elements (Ag, Cu, Au, P, Fe, Pd, Mn, Zn, Ir, Al, Cd, Ti, Ga, and Cr) with a combined value of US $280/ton of sludge.
authors.affiliation: †School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Westerhoff
authors.affiliation: †School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States.
authors.forename: Sungyun
authors.initials: S
authors.lastname: Lee
authors.affiliation: †School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yang
authors.affiliation: ‡School of Earth and Space Exploration, Arizona State University, Tempe, Arizona 85287-1404, United States.
authors.forename: Gwyneth W
authors.initials: GW
authors.lastname: Gordon
authors.affiliation: §The Polytechnic School, Ira A. Fulton Schools of Engineering, Arizona State University, Peralta Hall 330A, 7171 E. Sonoran Arroyo Mall, Mesa, Arizona 85212-2180, United States.
authors.forename: Kiril
authors.initials: K
authors.lastname: Hristovski
authors.affiliation: †School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, Arizona 85287-3005, United States.|∥Center for Environmental Security, The Biodesign Institute at Arizona State University, Security and Defense Systems Initiative, 781 E. Terrace Mall, Tempe, Arizona 85287-5904, United States.
authors.forename: Rolf U
authors.initials: RU
authors.lastname: Halden
authors.affiliation: ⊥Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287-1604, United States.
authors.forename: Pierre
authors.initials: P
authors.lastname: Herckes
mesh_terms: D001130:Arizona; D018533:Biomass; D003102:Colloids / Q000737:chemistry; D008670:Metals / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D052638:Particulate Matter / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D014481:United States; D014484:United States Environmental Protection Agency; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D003102:Colloids; D008670:Metals; D052638:Particulate Matter; D012722:Sewage; D062065:Wastewater