Phytofiltration Of Arsenic From Drinking Water Using Arsenic-Hyperaccumulating Ferns

Arsenic is a known carcinogen and mutagen and is detrimental to the immune system. Arsenic contamination of drinking water poses significant health risks to millions of people all over the world. Chronic exposure to As in drinking water at concentrations of 50μg/L may result in human cancer risks as high as 13 in 1000 or cause noncancer effects. Recently, increasing concerns have been paid from the scientists and public for the technology using hyperaccumulating plants to phytoremediate the contaminated environment. Recently, it has been found that P. vittata. efficiently remove As from As-contaminated soils. However, there are few studies on As removal from water solution by hyperaccumulator P. vittata.High As groundwater usually has high concentrations of chloride and bicarbonate. This study examined the effects of Cl-, HCO3-, and As species on As uptake by hyperaccumulator P. vittata. Plants were exposed hydroponically to 5.0 mg/L As(III) or 5.0 mg/L As(V) in the presence of 0, 0.5, 1, 2, 5, 10, 20 mM of Cl- or 0, 0.5, 1, 2, 5, 10, 20 mM of HCO3- for 10 d. Addition of high Cl- concentrations (> 5.0 mM) slightly inhibits P. vittata growth (biomass), while high Cl- concentration (up to 20 mM) generally has no effect on plant As uptake. In contrast, increasing HCO3- concentration results in greater suppression both in plant growth and in As uptake. The inhibitory effects of Cl- and HCO3- on plant growth and/or As uptake are less apparent for the As(III) treatments than the As(V) treatment. For the addition of Cl- (1-20 mM), As concentration of the growth media rapidly decreases at first 4 d of exposure, and generally keeps constant when exposure time increases from 4 to 10 d. About 60% As is removed in first 4 d in the As(III) treatment with amendment of 20 mM Cl-. For the addition of HCO3-, As concentration gradually decreases during 10 d of incubation. Around 25% As is depleted in the As(III) treatment with amendment of 20 mM HCO3-. The results suggest that optimum plant growth and maximum As hyperaccumulation could be achieved by maintaining moderate concentrations of HCO3- and Cl- (2-5 mM) in the growth media.With an initial arsenic (As(III) and As(V)) concentration of 1 mg/L, As removal is tested from deionized water-synthesized As solution and the nutrient solution- synthesized As solution. Research shows that the inhibitory effects on As uptake are less apparent for the As(III) treatments than the As(V) treatment. But, P. vittata take up more As in the deionized water-synthesized As solution than that the nutrient solution-synthesized As solution.In the deionized water-synthesized As solution, P. vittata takes up more As with As concentration of 5 mg/L than with As concentration of 10 mg/L.At last, we try to establish natural ecological bed, in which P. vittata can live better and remove As more efficiently.