1 IN-SITU REMOVAL OF ARSENIC FROM GROUNDWATER USING PERMEABLE REACTIVE BARRIERS WITH IRON BASED SORBENTS

Four types of materials have been used in the construction of permeable reactive barriers (PRB) used in the treatment of arsenic contaminated groundwater: zero valent iron (ZVI), furnace slag, sorbents and composite materials (organic + ZVI or a sorbent). Although barriers using sorbents are promising they are the less studied and no real applications, to our knowledge, have been implemented to the present. There are no published systematic studies regarding the potentialities of some iron oxides and hydroxides that are available in the market for a long time, such as ARM 300 and GEH 102. This research analyzes the capacities and drawbacks of these last two sorbents as materials for in-situ removal of arsenic using laboratory studies at batch scale and continuous operation in columns. Isotherms and breakthrough curves were determined for different operating conditions that are compared. Both sorbents adsorb As(III), As(V) and mixtures of both. Breakthrough curves allow determining the uptake capacity of both sorbents that are similar, 20 g As / kg, a consistent value somehow inferior to values already published in the literature. Finally it is studied the spatial distribution of arsenic concentration in the sorbent particles usin