Recovery of in-sewer dosed iron from digested sludge at downstream treatment plants and its reuse potential

Iron Transformation and Its Role in Phosphorus Immobilization in a UCT-MBR with Vivianite Formation Enhancement

“…Specifically, for the vUCT-MBR system used in the studies described here, in which vivianite formation/crystallization is enhanced in the sewage treatment units, the influence of sulfide on the vivianite route of P recovery differs, to some extent, to the case of anaerobic digesters. Oxidation of sulfide as FeS can be achieved in aerated activated sludge in hours with sulfate as the product. , The soluble sulfate ions would be discharged with the effluent, and the regenerated iron (as Fe III oxyhydroxides) would be recirculated to the anaerobic units of the vUCT-MBR. This approach, with necessary system optimization, can hopefully provide a way to eliminate the negative influence of sulfide through binding iron.…”

“…They proposed that the soil redox cycles induced alternate dissolution and precipitation of Fe III solids, accelerating the Ostwald ripening process and promoting the formation of more crystalline Fe minerals. Recently, Salehin et al 24 reported a more relevant phenomenon that the crystallinity of the inorganic fraction, with vivianite being a major form, in the thickened activated sludge increased to >40% during a 5 month experiment. The sludge was from a sequencing batch reactor (SBR) for sewage treatment, operated with a cyclic sequence of four operating stages, including 3 h of aerobic mixing.…”

“…Nitrogen removal in sludge digesters can also be improved by coupling Fe III reduction with anaerobic ammonium oxidation and possibly by NO x – -dependent Fe II oxidation . In lab-scale sludge thickeners and digesters/fermenters with Fe amendments, the formation of vivianite has been reported to play an important role in immobilizing P. − Vivianite has also been found to be a dominant P sink in full-scale WWTPs operated with Fe salt dosing. , …”

Magnetic nanoadsorbents for micropollutant removal in real water treatment: a review

“…Based on our analysis of the literature so far, we infer there is reasonable ground for developing a large-scale (industrial) usage of magnetic nanoadsorbents for water purification and wastewater treatment together with the incorporation of magnetic separation operating downstream for recovering the spent magnetic nanoadsorbents (Lee et al 2011 ; Liu et al 2013 ; Simeonidis et al 2015 ; Roy et al 2017 ; Mirshahghassemi et al 2017 ; Lompe et al 2018 ; Lingamdinne et al 2019b, a; Augusto et al 2019 ; Huang et al 2019 ; Prot et al 2019 ; Cui et al 2020 ; Ghernaout and Elboughdiri 2020 ; Abdel Maksoud et al 2020 ; Kheshti et al 2020 ; Powell et al 2020 ; Salehin et al 2020 ; Khan et al 2020 ; Hussen Shadi et al 2020 ; Acosta et al 2020 ; Rais et al 2021 ; Leonel et al 2021 ).…”

Effects of aging of ferric-based drinking water sludge on its reactivity for sulfide and phosphate removal

“…Rietveld refinements) were conducted to evaluate the degree of crystallinity of the Fe-DWS as a function of the sludge aging time as well as to determine the amount of different types of iron oxide in the Fe-DWS using TOPAS V-4.2 software. For this purpose, corundum (α-Al 2 O 3 ) was used as an internal standard for all semi-quantitative measurements following a procedure described previously (Salehin et al, 2019;Salehin et al, 2020).…”