Properties of recycled sludge formed from different aluminiferous reagents during the ettringite process

Sapsford, Devin James; Tufvesson, S.

doi:10.1016/j.jwpe.2017.08.016

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…The desirability value was 0.77, showing that our model could be successfully applied to experimental data. The researchers have found different optimum conditions to form ettringite minerals in previous studies [35][36][37]. This is reveal that the composition of wastewater had an effect on stoichiometric ratio of each reagents and operating pH.…”

Section: Optimization Resultsmentioning

confidence: 90%

Removal of sulphate from landfill leachate by crystallization

Aygün

Doğan

Argun

et al. 2018

Environmental Engineering Research

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The present study explores the applicability of response surface methodology (RSM) in conjunction with central composite design (CCD) matrix to statistically optimize ettringite crystallization process for the removal of sulphate from landfill leachate. A three factor-five coded level CCD with 20 runs, was performed to estimate the best fitted model. The RSM results indicated that the fitted quadratic regression model could be appropriate to predict sulfate removal efficiency. The pH was identified as the most dominant parameter affecting sulphate removal. 61.6% of maximum sulphate removal efficiency was obtained at pH of 11.06 for a 1.87 of Ca/SO4 and 0.51 of Al/SO4 molar ratios. The operating cost for ettringite crystallization at optimized conditions was calculated to be 0.52 $/m 3. The significance of independent variables and their interactions were tested by analysis of variance. Scanning electron microscope (SEM) and SEM coupled with energy dispersive X-Ray spectroscopy results confirmed the formation of ettringite crystal and were used to describe its morphology features.

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Section: Optimization Resultsmentioning

confidence: 90%

Removal of sulphate from landfill leachate by crystallization

Aygün

Doğan

Argun

et al. 2018

Environmental Engineering Research

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“…The typically used aluminium reagents, such as sodium aluminate are costly (Sapsford and Tufvesson, 2017;Tian et al, 2019). The choice of aluminium reagent has high impact on operational cost of the ettringite precipitation method.…”

Section: Introductionmentioning

confidence: 99%

“…A cost effective sulphate removal process using an aluminium-based proprietary reagent has also been suggested in the literature (Reinsel, 1999). The selection of aluminium reagent influences the efficiency of sulphate removal, as well as sludge density and sludge settling velocity (Sapsford and Tufvesson, 2017).…”

Section: Introductionmentioning

confidence: 99%

Removal of sulphate and arsenic from wastewater using calcium sulfoaluminate (ye’elimite)

et al. 2022

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Chemical precipitation is one of the most widely known methods for treatment of industrial wastewaters with high sulphate content, where sulphate can be precipitated as practically insoluble ettringite (Ca6Al2(SO4)3(OH)12·26H2O). This treatment method is also widely recognised for solidifying hazardous components and toxic elements e.g. arsenic in wastewater. In the ettringite precipitation process, lime and aluminium salts are typically used as starting materials, in stoichiometric amounts to form ettringite from the sulphate-containing water, leading to a pH rise to ∼11.5 and ettringite precipitation. In the current study, for the first time, ye’elimite mineral (Ca4Al6O12SO4), also known as calcium sulfoaluminate (CSA) in cements, is used in order to investigate its suitability to form ettringite precipitate from sulphate and arsenic containing synthetic wastewater and industrial wastewater solutions. The dissolution of ye’elimite prior to dosing, optimal precipitation pH, and arsenic co-precipitation were studied. The effluent and precipitates were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM-EDS) and inductively coupled plasma atomic emission spectroscopy (ICP-OES). The results showed that high percentage of sulphate removal (98% in the synthetic wastewater and 87% in the industrial wastewater) can be achieved using ye’elimite as the aluminium source in ettringite precipitation. Additionally, up to 95% arsenic removal was achieved in arsenic co-precipitation experiments from the synthetic wastewater. The current developed technology can be used as a novel ecological and cost-effective approach for removal of sulphate and toxic elements from wastewater.

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“…Sulphate precipitation as ettringite [11][12][13][14][15][16] is a modification of the high pH (>11) lime precipitation process [17].…”

Section: Introductionmentioning

confidence: 99%

Sulphate removal from mine water by precipitation as ettringite by newly developed electrochemical aluminium dosing method

Nurmesniemi¹,

Hu²,

Rajaniemi³

et al. 2021

Desalination and Water Treatment

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Precipitation as ettringite (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 •26H 2 O) is an effective method for sulphate removal from mine water. The addition of calcium hydroxide and aluminium to sulphate-containing mine water in stoichiometric amounts induces an increase in pH to approximately 12.5, leading to the precipitation of ettringite. Typically, aluminium salts are used as the source of aluminium; however, in this research, an electrochemical dosage of aluminium was used, and the results were compared with the results of chemical ettringite precipitation as well as the results of computational simulations of sulphate removal. The mine water sulphate concentration was reduced 99.0% and 98.6% from the initial 1,060 ± 20 mg L -1 using a current density of 28 mA cm -2 in electrochemical aluminium dosing and chemical aluminium dosing, respectively, which was close to the theoretical 100% sulphate removal. When using the current density of 28 mA cm -2 in the electrochemical aluminium dosing, the recovered ettringite purity was 92.5%, which was almost the same as the 92.6% purity in the chemical aluminium dosing characterised with X-ray diffraction and Rietveld analysis. The results indicate that the electrochemical dosing of aluminium could be an alternative to aluminium salt application in ettringite precipitation.

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Properties of recycled sludge formed from different aluminiferous reagents during the ettringite process

Cited by 7 publications

References 15 publications

Removal of sulphate from landfill leachate by crystallization

Removal of sulphate from landfill leachate by crystallization

Removal of sulphate and arsenic from wastewater using calcium sulfoaluminate (ye’elimite)

Sulphate removal from mine water by precipitation as ettringite by newly developed electrochemical aluminium dosing method

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