All these outcomes together have not been observed in the current most used processes of sulphate precipitation, i.e. gypsum and ettringite precipitation.

Ettringite formation can also provide a polishing effect, allowing precipitation of difficult-to-remove metals such as chromium, arsenic, selenium and cadmium, often below their respective analytical detection limits. Boron, fluoride and up to 30 percent of the chloride and nitrate in water have also been removed.

2020-01-01 · The precipitation rates of ettringite R total determined in all the experiments reported in this work can therefore be expressed as the sum of several contributions: the homogeneous nucleation rate R homo depending only on β, the secondary nucleation rate R sec depending on β, the number of crystals N and their surface S and the growth rate R growth depending on β and S. (11) R total = R The aluminium precipitation with the simultaneous formation of ettringite was chosen for laboratory testing as it is appropriate when the concentrations of sulphates have to be reduced-up to 300 Chemical precipitation. Sulphide precipitation; Precipitation with barium salts; Ettringite precipitation; Iron co-precipitation; Ion exchange; Membrane processes; Sulphate reduction in reactors; Treatment/disposal of water treatment residues; Passive treatment technologies. Aerobic constructed wetlands; Anaerobic constructed compost wetlands In the present study, ettringite precipitation was theoretically and experimentally evaluated as a means of sulphate removal. The results showed that ettringite precipitation is an effective and reliable method for sulphate removal. Synthetically prepared samples which were simulated to total wastewaters originating from the textile industry (sulphate concentration of 0.06 M) and to dye bath Ettringite precipitation based on formation of sulphate salts with low solubility can be used as a pretreatment method to overcome sulfate inhibition in anaerobic process. Calcium alumina-sulfate is commonly used to identify ettringite mineral. The following equation shows the basic chemical reaction to form ettringite Eq (1):) 1 ( A novel sulfate removal process via ettringite precipitation was developed by dissolving ettringite and recycling Al3+ under low pH condition.

• Softening and pH adjustment by re-carbonation. Figure 1 shows a schematic process flow diagram. All these outcomes together have not been observed in the current most used processes of sulphate precipitation, i.e. gypsum and ettringite precipitation. 22 Aug 2020 Alkali substituted C3A converted to ettringite faster and more completely solution due to premature precipitation of calcium pyrophosphate. The T-200B precipitation - rain gauge for all weather precipitation monitoring.

The prismatic crystals are typically colorless, turning white on partial dehydration. It is part of the ettringite-group which includes other sulfates such as thaumasite and bentorite. The effect of Mg 2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg 2+.

The formation of ettringite as a precipitate is another technique that can be used to treat mine-impacted water and has the capability of achieving sulphate concentrations that adhere to potable water and effluent discharge guidelines. Ettringite represents a group of acicular calcium aluminate hydrates (Damons and Petersen, 2002).

et al., 1996). This precipitation process is well-understood, reliable and can be easily controlled. The SAVMIN process is similar to the One of the main challenges in industrial wastewater treatment and recovery is the removal of sulfate, which usually coexists with Ca2+ and Mg2+. The effect of Mg2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg2+.

23 Nov 2018 Sulphate removal from mine water with precipitation as ettringite and further utilisation of the precipitate as arsenate sorbent was investigated in

The determined reconstruction time for ettringite lay within 1.2-4 years, which resulted in a dissolution-precipitation rate of 10 À 12.2 to 10 À 11.5 mol m À 2 days À 1 . For monosulfate, the data for the two series for 45 Ca agreed well, both resulting in a reconstruction time around 500 days. In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using Response Surface Methodology (RSM) and Central Composite Design (CCD). The statistical analysis of the results showed that the operating parameters such as molar rates of Ca/ SO4 and Al/SO4, and pH had a significant effect on sulfate removal ettringite precipitation Source. OnePetro (1) Date. 2020 (1) to. Go SPE Disciplines.

Sulphate control by ettringite precipitation in textile industry wastewaters In the present study, ettringite precipitation was theoretically and experimentally evaluated as a means of sulphate removal. The results showed that ettringite precipitation is an effective and reliable method for sulphate removal. Precipitation of ettringite The most common image of sulfate attack is associated with the precipitation of ettringite, leading to expansion and cracking. Ettringite is a calcium sulfoaluminate hydrate with a composition of C 6ASS 3H 32: As such, the penetrating sulfates need to ﬁnd a source of aluminium and calcium with which to react. Alumin- Ettringite was precipitated in the presence of TcO 4 –, IO 3 –, and/or CrO 4 2–, known contaminants of concern to nuclear waste treatment, over pre-determined precipitation periods.
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The SAVMIN process is similar to the One of the main challenges in industrial wastewater treatment and recovery is the removal of sulfate, which usually coexists with Ca2+ and Mg2+. The effect of Mg2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg2+. In the absence of Mg2+, the optimum conditions with sulfate removal of 99.7% were obtained at calcium-to-sulfate ratio of 3.20, aluminum-to-sulfate ratio of 1.25 and pH of 11.3 using response surface Ettringite was precipitated in the presence of TcO4-, IO3-, and/or CrO42-, known contaminants of concern to nuclear waste treatment, over pre-determined precipitation periods. Solution analyses quantified contaminant removal and the collected solid was characterized using bulk and microprobe XRD coupled with PDF and microprobe XRF more » analyses. The determined reconstruction time for ettringite lay within 1.2-4 years, which resulted in a dissolution-precipitation rate of 10 À 12.2 to 10 À 11.5 mol m À 2 days À 1.

Ettringite precipitation (Equation (2)) has been shown to be an effective method for sulphate removal, as it can reduce sulphate concentration to 200 mg/L (Madzivire et al. 2010). Ettringite is also considered to be stable waste for long-term disposal.
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Abstract In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using

After the precipitation reaction is complete, the ettringite solids are separated from the feed water, filtered and thickened. Due to the high sulphate removal efficiencies of 85-90 % (Tolonen et al., 2016) and of over 95-98 % (Fang et al., 2018) With regard to the precipitation rate of ettringite from solution (stage 3), Baur et al. 22) measured the dissolutionprecipitation reaction rate between the solid ettringite and the aqueous Abstract In the present study, experiments were conducted to optimize sulfate removal efficiency with ettringite precipitation from landfill leachate using ettringite precipitation Source.