Removal of Arsenic Compounds From Waste Water
Land disposal of arsenic containing waste, use of arsenic containing pesticides and ore smelting have resulted in increased environmental levels of arsenic containing compounds. (15, 13) A significant amount of these arsenic containing compounds contaminates waste water. An examination of any process for reducing increased levels of arsenic containing compounds in waste water involves an understanding of the chemistry of dissolved arsenic containing compounds, an effective method for measuring dissolved arsenic compounds, and an efficient system for removal of arsenic containing compounds from waste water. Removal of arsenic containing compounds should be addressed in the context of an integrated waste water management program.
Anderson and Bruland (1) examined the forms that arsenic containing compounds take in aqueous solution. Inorganic arsenic
may be found as arsenate (H2ASO4-), arsenite (AS(OH)3), arsine
(AsH3), monomethylarsenate (CH3AsO2OH-) , dimethylarsenate
((CH3)2AsO2OH-), dimethylarsine ((CH3)2AsH3) trimethylarsine
((CH3)2AsH3), and triethylarsine ((CH3-CH3)2AsH3). In a survey of
California lakes and rivers, total arsenic levels ranged from a low of 6.9 nM in Lake Ontario to a high of 230000 nM in Mono lake. The relatively high values in Mono Lake and Pyramid Lake (1300 nM) were two to six orders of magnitude higher than the values found in the other sites tested. (1) In this study, Mono Lake had the highest level of inorganic arsenic, at 230000 Mono Lake also had the highest level of methylated arsenic containing compounds.
Knowles and Benson have hypothesized that the source of the organoarsenicals are organisms that produce organoarsenicals from inorganic arsenic containing compounds in order to detoxify the inorganic arsenic compounds in their environment. (8) Yancey et al. indicate that methylation of arsenic containing compounds may play a ...