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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472
EISSN: 1735-2630
Vol. 12, No. 1, 2015, pp. 161-172
Bioline Code: st15014
Full paper language: English
Document type: Editorial
Document available free of charge

International Journal of Environment Science and Technology, Vol. 12, No. 1, 2015, pp. 161-172

 en Boron recovery from high boron containing wastewater using modified sub-micron Ca(OH)2 particle
Tsai, H.C. & Lo, S.L.

Abstract

In the present study, two modified calcium hydroxide (Ca(OH)2) particles, sub-micron Ca(OH)2 made by CaCl2 and Ca(NO3)2, were applied to improve efficiency of boron recovery from concentrated wastewater under mild temperature conditions. The two modified calcium hydroxide particles led to higher recovery efficiencies at 95 °C for 1 h (77.2 and 76.3 %) as compared to the efficiency by using un-modified Ca(OH)2 (67.2 %). The difference was due to their different particle size constitutions. For the reaction kinetic of boron removal, it was found that the pseudo-first-order model fitted well in the experimental data. The sub-micron Ca(OH)2 were used to remove and recover boron from a polarizer manufacturing wastewater. The findings revealed that it is worth recovering the boron containing precipitates because of the close boron content in the precipitates (sub-micron Ca(OH)2 made by CaCl2: 7.0 %, sub-micron Ca(OH)2 made by Ca(NO3)2: 7.1 %) as compared to natural boron minerals (borax: 11.3 %). In addition, in order to estimate energy efficiency of boron recovery by chemical precipitation method, an evaluating formula, energy consumption of boron uptake, was developed. The value of energy consumption of boron uptake by using sub-micron Ca(OH)2 made by CaCl2 with the optimum condition was comparatively high (35.4 μg-B/g-Ca(OH)2/kJ). Therefore, the sub-micron Ca(OH)2 particles were observed more effective for boron recovery from concentrated wastewater under moderate temperatures.

Keywords
Sub-micron particle; Chemical precipitation; Boron removal; Boron recovery; Polarizer manufacturing wastewater

 
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