ABSTRACT
Nowadays nanofiltration has been considered for the treatment of organic and inorganic pollutants in surface and groundwater resources. In this study, rejection characteristics of arsenic compounds such as As[III] to form As[2]O[3] and As[V] to form Na[2]HasO[4].7H[2]O by a commercial nanofilter NF90 [DOW-FilmTec] was investigated. Arsenic rejection experiments included variations of feed arsenic concentration, transmembrane pressure and pH. In these experiments, as increasing initial concentration As[V] from 120 micro g/L to 1026 micro g/L in feed water, the percentage of rejection of As[V] decreased from 98.35% to 96.59% [permeate water concentration was 2 micro g/L to 35 micro g/L], while as increasing initial concentration As[III] from 118 micro g/L to 985 micro g/L in feed water, the percentage of rejection of As[III] decreased from 94.07% to 87.51% [permeate water concentration was 7 micro g/L to 123 micro g/L]. Due to increase of pressure from 4 bar to 7 bar, the percentage of rejection of As[V] in finished water increased from 95.68% to 99.02% [permeate water concentration decreased from 21 micro g/L to 5 micro g/L],while the percentage of rejection of As[III] decreased from 80.99% to 95.11% [permeate water concentration decreased from 96 micro g/L to 25 micro g/L]. Also due to increasing pH from 3 to 11, the percentage of rejection of As[V] in finished water increased from 95.45% to 99.00% [permeate water concentration decreased from 22 micro g/L to 5 micro g/L], while the percentage of rejection of As[III] decreased from 86.6% to 94.81% [permeate water concentration decreased from 65 micro g/L to 25 micro g/L]. Finally, nanofiltration application for arsenic removal from drinking water was recognized suitable regarding its proper efficiency and convenience operation and was recommended for point-of-use applications