Iron-phosphate compound identification in sewage sludge residue

Seitz, Michelle E.; Riedner, R. J.; Malhotra, S. K.; Kipp, Raymond J.

doi:10.1021/es60076a005

Cited by 12 publications

(4 citation statements)

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“…In addition to a certain amount of Si and S in some particles, Ca, Al, and Mg coexisted at relatively high concentrations with the Fe phosphate minerals (Table S7). Impurity inclusion of Fe phosphate minerals is common, as other cations can replace Fe atoms in Fe phosphate mineral structures. − Previous studies also showed that vivianite is not present as free particles in anaerobically digested sludges. , …”

Section: Resultsmentioning

confidence: 99%

Effect of Interstage Hydrothermal Treatment on Anaerobic Digestion of Sewage Sludge: Speciation Evolution of Phosphorus, Iron, and Sulfur

Wang

Zhang

Liu

et al. 2020

ACS Sustainable Chem. Eng.

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Anaerobic digestion (AD) with interstage hydrothermal treatment (HT) (i.e., AD−HT−AD) is an emerging technology for energy and nutrient recovery from sewage sludge. Yet, systematic understanding on the speciation evolution of nutrient phosphorus (P) and other redox-sensitive elements iron (Fe) and sulfur (S) during AD−HT−AD is still missing. This study investigated the coupled changes of P, Fe, and S speciation during AD−HT−AD of sewage sludge using complementary chemical extraction, microscopy, and spectroscopy analyses. Results indicated that after the first-stage AD a significant fraction of Fe was present as vivianite in the AD solids due to the microbial reduction of strengite and other Fe(III) species. During HT of the anaerobically digested solids, less vivianite but more strengite formed in the HT hydrochars with increasing HT temperature. Partial auto-oxidation of vivianite by H 2 O at high HT temperatures (155 and 185 °C) induced the formation of strengite. For the second-stage AD, more vivianite formed in AD solids as compared to that in their corresponding hydrochars from higher HT temperatures (155 and 185 °C). Regarding S speciation, both AD stages and HT favored the formation of iron sulfides. Results from this study suggest that the cycling of both P and S is strongly coupled with Fe chemistry. This study sheds light on the reaction mechanisms during AD−HT−AD of sewage sludge and the nutrient recycling and reclamation options for sewage sludge management.

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Section: Resultsmentioning

confidence: 99%

Effect of Interstage Hydrothermal Treatment on Anaerobic Digestion of Sewage Sludge: Speciation Evolution of Phosphorus, Iron, and Sulfur

Wang

Zhang

Liu

et al. 2020

ACS Sustainable Chem. Eng.

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“…In WWTP's dosing iron, several researchers reported the presence of the iron phosphate mineral vivianite (Fe 3 (PO 4 ) 2 .8H 2 O). Frossard et al 1997 discovered sand-sized to silt-sized vivianite in sludge while Seitz et al 1973 observed it in dried sewage sludge. Nriagu and Dell 1974 evaluated that vivianite was the most thermodynamically stable FeP mineral in reductive environments, such as in sediments and sludge.…”

Section: Introductionmentioning

confidence: 99%

“…Magnetic separation would, therefore, provide a selective way to recover vivianite from sludge. Seitz et al 1973, already designed an experimental set-up to separate vivianite from dried sludge powder using magnetic attraction. There are also other devices from the mining industry like the Frantz separator that were used to extract magnetic fractions from streams but never tested to extract vivianite from sludge.…”

Section: Introductionmentioning

confidence: 99%

Magnetic separation and characterization of vivianite from digested sewage sludge

Prot

Nguyen²,

Wilfert

et al. 2019

Separation and Purification Technology

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To prevent eutrophication of surface water, phosphate needs to be removed from sewage. Iron (Fe) dosing is commonly used to achieve this goal either as the main strategy or in support of biological removal. Vivianite (Fe(II) 3 (PO 4 ) 2 *8H 2 O) plays a crucial role in capturing the phosphate, and if enough iron is present in the sludge after anaerobic digestion, 70 to 90% of total phosphorus (P) can be bound in vivianite. Based on its paramagnetism and inspired by technologies used in the mining industry, a magnetic separation procedure has been developed. Two digested sludges from sewage treatment plants using Chemical Phosphorus Removal were processed with a lab-scale Jones magnetic separator with an emphasis on the characterization of the recovered vivianite and the P-rich caustic solution. The recovered fractions were analyzed with various analytical techniques (e.g., ICP-OES, TG-DSC-MS, XRD and Mössbauer spectroscopy). The magnetic separation showed a concentration factor for phosphorus and iron of 2-3. The separated fractions consist of 52% to 62% of vivianite, 20% of organic matter, less than 10% of quartz and a small quantity of siderite. More than 80% of the P in the recovered vivianite mixture can be released and thus recovered via an alkaline treatment while the resulting iron oxide has the potential to be reused. Moreover, the trace elements in the P-rich caustic solution meet the future legislation for recovered phosphorus salts and are comparable to the usual content in Phosphate rock. The efficiency of the magnetic separation and the advantages of its implementation in WWTP are also discussed in this paper.

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“…Vivianite is a biogenic mineral product of dissimilatory metal reduction bacteria (DMRB). Though the existence of vivianite in sludge has been known for a long time, − its potential in phosphorus recovery was only recognized recently and accounts for 40–50% in iron-based phosphorus removal. , As a dominant component of sludge phosphorus with a higher P content (a Fe:P molar ratio of 1:0.67 compared to 1:0.4 for ferric FeP precipitates in wastewater experiments), vivianite is believed to be the most important phosphorus pool and a promising route for phosphorus recovery in WWTPs . However, since the growth of DMRB also consumes phosphate, chemical vivianite formation is usually a competition between phosphorus and bacteria, which is a significant problem in real systems.…”

Section: Introductionmentioning

confidence: 99%

Phosphorus Competition in Bioinduced Vivianite Recovery from Wastewater

Shu

Wan

et al. 2018

Environ. Sci. Technol.

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Phosphorus undergoes a one-way flow from minerals to soil to water, which creates a phosphorus crisis as well as aquatic eutrophication. Dissimilatory metal reduction bacterial (DMRB)induced vivianite recovery from wastewater is a promising route to solve these problems synthetically. In this study, phosphorus competition between biomass growth and bioinduced vivianite mineralization was investigated at the batch scale. Biomass growth leads to phosphorus utilization over vivianite mineralization. Geobacter was selected as the main functional microorganism and presented higher vivianite recovery rates (20−48%) than sewage biomass (7−33%). An optimal Fe/P stoichiometric ratio of 1:1 was observed for both sewage biomass and Geobacter-inoculated batches. The highest vivianite yield of 4.3 mM was obtained in Geobacter-inoculated batches at a Fe:P of 1:1, with values 59% higher than those at a Fe:P of 1:0.67 (equal to the Fe/P molar ratio in vivianite). Sufficient PO 4 3− stimulated cell growth and yielded a higher Fe 3+ reduction rate and vivianite yield. Nevertheless, excessive PO 4 3− facilitated the precipitation of KFe 3 (PO 4 ) 2 (OH)• 8H 2 O and Fe 7 (PO 4 ) 6 , which inhibited vivianite synthesis. In the optimal Geobacter batch, the μ−S curve indicated a mixed order reaction (0 < x < 1) for both vivianite formation and biomass growth. The vivianite growth series proceeded as follows: tiny blue particles, plain pieces, dark blue nodules, and large spherical crystals.

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Iron-phosphate compound identification in sewage sludge residue

Cited by 12 publications

References 0 publications

Effect of Interstage Hydrothermal Treatment on Anaerobic Digestion of Sewage Sludge: Speciation Evolution of Phosphorus, Iron, and Sulfur

Effect of Interstage Hydrothermal Treatment on Anaerobic Digestion of Sewage Sludge: Speciation Evolution of Phosphorus, Iron, and Sulfur

Magnetic separation and characterization of vivianite from digested sewage sludge

Phosphorus Competition in Bioinduced Vivianite Recovery from Wastewater

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