Subsurface arsenic removal column tests: from the laboratory to the field
D. H. Moed1, D. van Halem1, J. Q. J. C. Verberk1, J. A. M. van Paassen2, and L. C. Rietveld11Delft University of Technology, Faculty of Civil Engineering and Geosciences, Stevinweg 1, 2628 CN Delft, The Netherlands 2Vitens, Oude Veerweg 1, 8019 BE Zwolle, The Netherlands
Received: 17 Apr 2012 – Accepted for review: 06 May 2012 – Discussion started: 30 May 2012
Abstract. Previous laboratory column experiments have given evidence of competitive effects between different groundwater constituents in the process of subsurface arsenic removal, a process in which arsenic is removed from groundwater by injecting water with oxygen into the subsurface. The presence of phosphate and other anions significantly limited arsenic removal. To investigate the influence of phosphate in natural groundwater, pumping stations in Loosdrecht (the Netherlands) and Subotica (Serbia) both with low phosphate concentrations (<0.1 mg l−1) and considerable arsenic concentrations (30 and 110 μg l−1) were chosen, to perform experiments identical to the previous laboratory work. Despite of the absence of phosphate, the subsurface arsenic removal process performed poorly in Subotica, with 50% arsenic breakthrough occurring after 2 to 4 column pore volumes of abstracted water. In Loosdrecht subsurface arsenic removal showed more promising results, 50% breakthrough after 6 to 7 pore volumes, while having a lower pH than Subotica and similar silicate concentrations. The water composition of both locations gives reason to suggest that natural organic matter has a limiting effect on subsurface arsenic removal as well. The presented results have shown the complexity of factors influencing subsurface arsenic removal, making it very challenging to select appropriate sites.
Moed, D. H., van Halem, D., Verberk, J. Q. J. C., van Paassen, J. A. M., and Rietveld, L. C.: Subsurface arsenic removal column tests: from the laboratory to the field, Drink. Water Eng. Sci. Discuss., 5, 193-207, doi:10.5194/dwesd-5-193-2012, 2012.