31-11 Removal of Arsenic (As) from Mississippi Lakes using Raw Bauxite found in Northern Mississippi

Session: Environmental Geochemistry and Health (Posters)

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Abstract:

Arsenic is being introduced to lakes within Mississippi due to multiple processes (e.g. runoff from farmlands or production waste). There are growing health concerns as most lakes are used recreationally by millions of people. Extended exposure to arsenic can lead to skin damage and multiple forms of cancer. Enid Lake, Mississippi, is used for fishing and swimming by locals. Using previous data, the lake has an average As level between 4 to 6 µg/L. The EPA sets the maximum contaminant level (MCL) is 10µg/L, but the maximum contaminant level goal (MCLG) at 0µg/L for As, so health effects can still be caused by extended exposure. Using bauxite, which is an abundant geological unit in northern Mississippi, is a more efficient and cheaper alternative to other treatment methods. This study will use raw clay-rich-bauxite to investigate the efficient removal of contaminants (e.g. As) following sorption models. 

Fifteen water samples were collected; over 5 locations in Enid Lake. Physicochemical parameters such as pH, temperature, specific conductivity, ORP, and dissolved oxygen have been recorded at each sampling location. The average pH recorded at 7.22; temperature was 25.26°C; specific conductivity was 52.44 µS/cm; ORP was 104 mV; and 8.68mg/L dissolved oxygen. Two series of preliminary batch experiments were performed to remove arsenic. The first batch uses a solution containing 1 g/L of bauxite while the second batch uses 10g/L of bauxite. The lake samples were spiked with arsenic to reach the MCL and allowed 24-hour contact time with the bauxite. Every sample in the second batch shows 100% removal of As, while 50% of the samples show efficient As removal in the first batch with the lower bauxite dosage. The detection limit for both experiments was about 65%, but it is assumed at least 90% was removed from the samples. This confirms that raw bauxite sorption capacity is efficient in removing As.

Further sorption experiments will be performed in Ross Barnett Reservoir near Jackson, Mississippi area. The preliminary data indicates that raw bauxite has a high potential to be a cost-effective material to remove As efficiently from contaminated lake water. 

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