Improved removal of arsenic from groundwater using pre-corroded steel and iron tailored granular activated carbon.
The authors have combined corrosion of steel fittings or perforated sheets with granular activated carbon (GAC) that had been pre-treated with Fe(III)-citrate, to produce an innovative and low-maintenance technique for removing arsenic from groundwater. Removal of arsenic was measured using two GAC column configurations: rapid small scale column tests (RSSCT's) and mini-column tests. Independent variables included pH, pre-corrosion procedure, and idling of the column (i.e. intentionally stopping flow for defined times in order to create reducing conditions). Use of corroded steel plus pre-treated GAC removed arsenic to below 10 microg/L for up to 248,000 bed volumes (BV) at pH 6, compared to 7,000 BVs for pre-treated GAC without pre-corroded steel. Performance was not as good at pH 6.5 or 7.5. Idling the system recovered the iron corrosion ability by reducing the passive Fe(III) layer on pre-corroded steel surface, as a result the BVs to arsenic breakthrough was doubled. But idling also caused brief periods of arsenic and iron release after restart, due to reductive dissolution of arsenic-containing ferric oxides. GAC was also effective as filtration media for removal of iron (hydr)oxide particles (and associated arsenic) that was released from the pre-corroded iron.
Zou
J
J
Department of Civil and Enviornmental Engineering, The Pennsylvania State University, University Park, PA 16802, USA. jzz107@psu.edu
Cannon
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FS
Chen
W
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Dempsey
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BA
D001151:Arsenic / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D003343:Corrosion; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D013232:Steel / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D014874:Water Pollutants, Chemical; D013232:Steel; D002244:Carbon; D007501:Iron; D001151:Arsenic