Health aspects of burning coal with a high arsenic content

Globally, arsenic introduced into the biosphere by human activities has greatly surpassed arsenic from natural sources, the supply of the element from these two sources being approximately 60 and 40%, respectively. However, numerous regions of the world have elevated concentrations of arsenic from natural sources. Arsenopyrite may contain up to 6000 μg∙g−1 of arsenic and the weathering of such geological materials can increase the levels of arsenic in groundwater. Long-term consumption of groundwater containing elevated concentrations of arsenic has caused natural chronic arsenic intoxication in local populations in Taiwan, Mexico, Chile, Argentina, and other countries. An endemic disease commonly called blackfoot disease, which is also caused by arsenic in drinking water, was documented in Taiwan in 1963. For more than 80 years local populations had consumed well water with arsenic concentrations as high as 1829 μg∙L−1. The widespread geographical distribution of minerals with high arsenic content suggests that many new regions with natural arsenic contamination will be identified in the near future.Key words: arsenic, natural, cycling, chronic, contamination.

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Bioprecipitation of Arsenic Sulphide at Low pH

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.71-73.581 ◽

2009 ◽

Vol 71-73 ◽

pp. 581-584 ◽

Cited By ~ 3

Author(s):

F. Battaglia-Brunet ◽

Dominique H.R. Morin ◽

S. Coulon ◽

Catherine Joulian

Keyword(s):

Bacterial Population ◽

Removal Rate ◽

Bacterial Consortium ◽

Low Ph ◽

Operating Conditions ◽

Arsenic Content ◽

Molecular Fingerprints ◽

Ph Values ◽

Reducing Activity ◽

High Arsenic

A process for the precipitation of trivalent arsenic sulphide in sulphate-reducing condition at low pH would be very attractive due to the high arsenic content (60%) in the final precipitate. A bacterial consortium able to reduce sulphate at pH 4.5 served to inoculate column bioreactors that were continuously fed with As(V) or As(III), glycerol and/or hydrogen, at pH values between 2 and 5. The diversity, functionality and evolution of the consortium colonizing the bioreactors were characterized by means of biomolecular tools, in relation with operating parameters (pH, As, sulphide, acetate). The highest As removal rate obtained during these experiments was close to 3 mg.l-1.h-1 using As(V) as the initial arsenic form, while precipitation rates were improved using As(III). When glycerol was replaced by hydrogen in a bioreactor containing a mature biofilm, sulphate-reducing activity increased roughly. Organisms related to Desulfosporosinus were the only sulphate-reducing bacterium (SRB) detected in the bioreactor. arrA genes, involved in As(V) dissimilatory reduction, were also detected and suggested that As(V) was reduced by a Desulfosporosinus-like organism. Molecular fingerprints evidenced an evolution of the bacterial population structure according to changes in operating conditions.

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