Performance of Ca(OH)2–Al2(SO4)3 Addition Method in Removing Boron from Wastewater Discharged from Flue-Gas Desulfurizer

JOURNAL OF CHEMICAL ENGINEERING OF JAPAN

Yuki Hiraga¹  Naoya Shigemoto¹ 

[1] Chemical Technology Department, Shikoku Research Institute, Inc.

关键词: Ettringite;    Boron Removal;    Wastewater Treatment;    Precipitation;   

DOI  :  10.1252/jcej.10we307

来源: Maruzen Company Ltd

【 摘 要 】

References(15)Cited-By(1)After adding Al2(SO4)3 to wastewater that was discharged from a flue-gas desulfurizer, alkalization by solid Ca(OH)2 or NaOH solution was carried out in order to examine the effects of the reaction conditions such as the concentration of the Al2(SO4)3 that was added and the pH of solution on the precipitation of the boron in the wastewater. Higher concentrations of Al2(SO4)3 added into the wastewater resulted in the precipitation of larger amounts of boron. The amount of precipitated boron increased with an increase in the pH of the reacted wastewater solution and attained the peak or plateau value at pH values in the range of 10 to 12. The concentration of the precipitated boron was in proportion to the concentration of precipitated Al(OH)3 at pH <10 and to the concentration of precipitated ettringite at pH >10. Alkalization by Ca(OH)2, rather than by NaOH, promoted the formation of ettringite and thereby promoted the removal of boron. It was found that if the SO4/Al, Ca/Al, and OH/Al molar ratios of the feed wastewater solution were higher than the corresponding theoretical molar ratios of ettringite, the formation of ettringite was promoted.

【 授权许可】

Unknown