Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Sulfate removal from wastewater using ettringite precipitation: Magnesium ion inhibition and process optimization
One of the main challenges in industrial wastewater treatment and recovery is the removal of sulfate, which usually coexists with Ca.sup.2+ and Mg.sup.2+. The effect of Mg.sup.2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg.sup.2+. In the absence of Mg.sup.2+, 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 methodology. In the presence of Mg.sup.2+, sulfate removal efficiency decreased with increasing Mg.sup.2+ concentration, and the inhibitory effect of Mg.sup.2+ matched the competitive inhibition Monod model with half maximum inhibition concentration of 57.4 mmol/L. X-ray diffraction and Fourier transform infrared spectroscopy analyses of precipitates revealed that ettringite was converted to hydrotalcite-type (HT) compound in the presence of Mg.sup.2+. The morphology of precipitates was transformed from prismatic crystals to stacked layered crystals, which confirmed that Mg.sup.2+ competes with Ca.sup.2+ for Al.sup.3+ to form HT compound. A two-stage process was designed with Mg.sup.2+ removal before ettringite precipitation to eliminate the inhibitory effect, and is potential to realize sludge recovery at the same time of effective removal of sulfate and hardness.
Sulfate removal from wastewater using ettringite precipitation: Magnesium ion inhibition and process optimization
One of the main challenges in industrial wastewater treatment and recovery is the removal of sulfate, which usually coexists with Ca.sup.2+ and Mg.sup.2+. The effect of Mg.sup.2+ on sulfate removal by ettringite precipitation was investigated, and the process was optimized in the absence and presence of Mg.sup.2+. In the absence of Mg.sup.2+, 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 methodology. In the presence of Mg.sup.2+, sulfate removal efficiency decreased with increasing Mg.sup.2+ concentration, and the inhibitory effect of Mg.sup.2+ matched the competitive inhibition Monod model with half maximum inhibition concentration of 57.4 mmol/L. X-ray diffraction and Fourier transform infrared spectroscopy analyses of precipitates revealed that ettringite was converted to hydrotalcite-type (HT) compound in the presence of Mg.sup.2+. The morphology of precipitates was transformed from prismatic crystals to stacked layered crystals, which confirmed that Mg.sup.2+ competes with Ca.sup.2+ for Al.sup.3+ to form HT compound. A two-stage process was designed with Mg.sup.2+ removal before ettringite precipitation to eliminate the inhibitory effect, and is potential to realize sludge recovery at the same time of effective removal of sulfate and hardness.
Sulfate removal from wastewater using ettringite precipitation: Magnesium ion inhibition and process optimization
Dou, Weixiao (Autor:in) / Zhou, Zhen / Jiang, Lu-Man / Jiang, Aijian / Huang, Rongwei / Tian, Xiaoce / Zhang, Wei / Chen, Dongqing
2017
Aufsatz (Zeitschrift)
Englisch
BKL:
43.00
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