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

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Sirajus Salehin
  • Jagadeesh kumar Kulandaivelu
  • Mario Rebosura Jr.
  • Olaf van der Kolk
  • Jürg Keller
  • Katrin Doederer
  • Wolfgang Gernjak
  • Bogdan C. Donose
  • Ilje Pikaar

Detail(s)

Original languageEnglish
Article number116179
Journal / PublicationWater Research
Volume184
Online published13 Jul 2020
Publication statusPublished - 1 Oct 2020
Externally publishedYes

Abstract

Recent studies demonstrated the practical potential of multiple beneficial reuse of ferric-rich drinking water sludge (ferric DWS) for sulfide and phosphate removal in wastewater applications. In practice, ferric DWS is often stored on-site for periods ranging from days to several weeks (or even months), which may affect its reuse potential through changes in iron speciation and morphology. In this study, we investigated for the first time the impact of ferric DWS ‘aging’ time on the iron speciation and morphology and its subsequent impact on its reactivity and overall sulfide and phosphate removal capacity. A series of coagulation tests were conducted to generate ferric DWS of a practically relevant composition by using raw influent water from a full-scale drinking water treatment plant (DWTP). A comparison with ferric DWS from 8 full-scale DWTPs confirmed the similitude. The presence of akaganeite (β-FeOOH) was detected in ferric DWS (through XRD analyses), independent of the DWS storage time. However, the morphology of akaganeite changed over time from a predominant poorly-crystalline phase in ‘fresh’ DWS (8 ± 0.1% of total Fe) to a highly crystalline phase (76 ± 3% of total Fe) at a sludge aging time of 30 days which was confirmed by means of Rietveld refinement in XRD analyses (n = 3). Subsequent batch tests showed that its sulfide removal capacity decreased significantly from 1.30 ± 0.02 mmol S/mmol Fe (day 1) to 0.60 ± 0.01 (day 30), a decrease of 54 % (p < 0.05). The level of crystallinity however had no impact on sulfide removal kinetics, most sulfide being removed within 10 minutes. Upon aeration of sulfide-loaded ferric DWS in activate sludge, amorphous iron oxides species were formed independent of the initial DWS crystallinity which resulted in efficient P removal at capacities similar to that of conventional FeCl3 dosing. © 2020 Elsevier Ltd.

Research Area(s)

  • Circular economy, Coagulant reuse, Drinking water sludge, Phosphate removal, Resource recovery, Sulfide control

Citation Format(s)

Effects of aging of ferric-based drinking water sludge on its reactivity for sulfide and phosphate removal. / Salehin, Sirajus; Kulandaivelu, Jagadeesh kumar; Rebosura Jr., Mario et al.
In: Water Research, Vol. 184, 116179, 01.10.2020.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review