Treatment Alternatives for Nitrate Contaminated Groundwater Supplies
Mohamed F. Dahab
AbstractNitrate concentrations in groundwater supplies throughout many areas in the United States, particularly in the Midwest, have steadily increased well past the Maximum Contaminant Limit established by the Safe Drinking Water Act of 1974 and its amendments of 1986. The concern over nitrate contamination stems from the fact that these salts have been linked to infant methemoglobinemia (blue-baby syndrome). Nitrates also have been linked to the formation of nitrosoamines and nitrosoamides, which are potent carcinogens. There are several methods of removing nitrates from groundwater supplies with varying degrees of efficiency, cost, and relative ease. These methods include anion exchange, biological denitrification, reverse osmosis, electrodialysis, and potentially chemical precipitation. The technical feasibility and economics of these processes indicate that only the first three can be considered viable at the present. This article is intended to discuss the relative technical feasibility of removing nitrates from groundwater supplies when using the above mentioned methods. Results from bench-scale experiments as well as data from the literature are used to develop a basis of comparison. The results of this effort indicate that ion-exchange is most advantageous when dealing with moderate nitrate contamination situations. However, in extreme contamination cases, biological denitrification followed by other water purification processes seems to be the most effective method of treatment.
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