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SUMMARY:EESS talk on "Addressing the arsenic crisis in Bangladesh: Geochem
 istry and adapted technologies"
DTSTART:20160524T121500
DTEND:20160524T131500
DTSTAMP:20260427T204145Z
UID:a071b53a2186d4891df4a69d37f5cdeb9af664bbec860f93a5b0ed8f
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr Stephan Hug\, head of Chemistry and Water Resources\, EAWAG
 \, CH\nAbstract:\nGroundwater aquifers are the main source of water for dr
 inking and for irrigation in Bangladesh. Since the early 1990s it is known
  that the groundwater in large regions of Bangladesh and other countries c
 ontains arsenic at concentrations from 50-1000 µg/L\, multiple times high
 er than the WHO limit of 10 µg/L and local limits of 50 µg/L. Despite la
 rge efforts and significant successes\, over 20 million people in Banglade
 sh still consume drinking water with arsenic above these limits.\nThe most
  successful measure has been the targeting of deeper aquifers with lower A
 s-concentrations\, but more detailed studies have shown that the optimal d
 epth for deep tubewells has to be determined locally to minimize other unw
 anted solutes such as manganese and salt. Arsenic removal remains an impor
 tant option in areas where arsenic-free water is not available.\nAmong the
  most promising arsenic removal technologies with inexpensive and locally 
 available materials are filters using zero-valent iron (ZVI). The corrosio
 n of ZVI under oxic and anoxic conditions produces a variety of reactive i
 ntermediates and solid phases that can transform and immobilize inorganic 
 and organic pollutants. In intermittently oxic and anoxic ZVI-layers in sa
 nd filters\, As(III) is oxidized to more strongly adsorbing As(V) by oxidi
 zing intermediates and incorporated into iron oxide phases. The slow trans
 formation of initially formed voluminous iron(hydr)oxides to denser phases
  such as magnetite are crucial processes that can explain the long-term ef
 ficiency and functioning of some types of ZVI-based filters\, such as the 
 SONO-filters which are deployed in large numbers in Bangladesh. The presen
 tation will focus on geochemical processes of arsenic release and sequestr
 ation and on strategies to improve the efficiency and application of ZVI-f
 ilters for arsenic removal.Short biography:\nStephan Hug studied chemistry
  at the Technikum (Fachhochschule) in Burgdorf and then went to\nthe Unite
 d States\, where he completed his studies and research in biophysical chem
 istry with a PhD degree from the University of California at Santa Cruz in
  1989. After a postdoc in the department of chemistry at Stanford Universi
 ty\, he returned to Switzerland and started a tenure track position as a r
 esearcher in aquatic chemistry at Eawag in Duebendorf in 1992.  Since 200
 0\, he leads the research group “Chemistry of Water Resources” in the 
 department of “Water Resources and Drinking water” at Eawag. His main 
 research interests are the biogeochemical cycling of metals and trace elem
 ents in ground- and surface waters and the treatment of polluted waters wi
 th adapted technologies.
LOCATION:GR C0 01 http://plan.epfl.ch/?room=GR%20C0%2001
STATUS:CONFIRMED
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