Performance on simultaneous removal of arsenic, fluoride and alkalinity (bicarbonate) by pilot scale Nanofiltration

HUGO SAITUA AND ANTONIO PEREZ PADILLA

DESALINATION

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2010 p. 16 - 21

0011-9164

Abstract In this research, it has been evaluated the efficiency and the arsenic removal mechanism with a Nanofiltration (NF) pilot plant from naturally contaminated groundwater. The process integral evaluation at 10 bar shows a arsenate (HAsO4²-) rejection over a 95% and a total sulfate (SO4²-) rejection. Divalent ions calcium and magnesium (Ca²+ and Mg²+) rejection produced an 81% reduction of the total hardness. The total dissolved solids TDS concentration decreased in a 53%. Monovalent ions moderated rejections contributed to the membrane hydraulics stability. The  arsenate (HAsO4²-) rejection from a polyelectrolytes solution (SO42-, HCO3-, F-, Cl-, NO3-, Ca2+, Mg2+, K+ and Na+) was prevalently ruled by Donnan exclusion combined with the preferential passage of more permeable ions. Results show the importance of ionic composition on ions transmission and rejection in the studied membrane. Ions rejection in multicomponent solutions showed to be significantly different to that in individual salt solutions. Whereas monovalent anions rejections remarkably decreased, divalent cations rejections were three times superior. In arsenate rejection (HAsO4²-) from artificially contaminated natural groundwater, the membrane showed the same selectivity.