Mg/Al LDH Enhances Sulfate removal and Clarification of AMD Wastewater in Precipitation Processes

Materials

Tiina Leiviskä¹  Jakub Matusik²  Paulina Maziarz³ 

[1] AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Krakow, Poland;Faculty of Geology, Geophysics and Environmental, Protection;Department of Mineralogy, Petrography and Geochemistry;

关键词: acid mine drainage water;    sulfate;    precipitation;    layered double hydroxides;    calcium hydroxide;   

DOI  :  10.3390/ma12142334

来源: DOAJ

【 摘 要 】

The sulfate removal from acid mine drainage (AMD) water (initial concentration: 5301 mg/L) was investigated by precipitation and/or adsorption using calcium hydroxide (Ca(OH)₂) and synthetic layered double hydroxide (LDH) of the Mg/Al type. The exclusive use of LDH efficiently removed sulfates (64.2% reduction); however, alteration of its structure was observed due to low pH. The use of Ca(OH)₂ in different doses calculated in relation to gypsum stoichiometry allowed to achieve an 86% removal of sulfates. Depending on the equilibrium pH, gypsum or ettringite were the main identified phases. The two-step removal, involving the use of Ca(OH)₂ followed by LDH, was less efficient than the use of the Ca(OH)₂/LDH mixture when the stoichiometric amount of Ca(OH)₂ in relation to gypsum was applied. The application of mixture resulted in a fast pH increase, which prevented destruction of the LDH structure. Most importantly, the use of mixture significantly reduced the sludge volume and enhanced its settling velocity.

【 授权许可】

Unknown