Author
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Hunter, William |
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Submitted to: Book Chapter
Publication Type: Book / Chapter Publication Acceptance Date: 1/31/2006 Publication Date: 7/20/2008 Citation: Hunter, W.J. 2008. Remediation of drinking water for rural populations. Book Chapter. pp 597-621, J.L. Hatfield and R.F. Follett (eds). Nitrogen in the Environment; Sources, Problems, and Management. 2nd editiion. Elsevier Sci Pubs. Interpretive Summary: Nitrate contamination of rural drinking waters is a common and growing problem in the US, Europe, and in other parts of the world. Agricultural activities, especially fertilizer use, have contributed to the problem. Ingestion of nitrate is a concern because of the effects that nitrate can have on human and animal health. While nitrate is not very toxic, nitrate is easily converted to nitrite which is toxic. Methemoglobinemia or blue baby syndrome is associated with the ingestion of nitrate. In the US it is recommended that human drinking water contain no more the 10 mg/L nitrate-nitrogen. At the present time methods for removing nitrate from drinking water include reverse osmosis, electrodialysis, ion exchange, and distillation. Systems under development include biological denitrification and catalytic systems. Technical Abstract: Nitrate is the most common nitrogen contaminant in raw water supplies. In rural areas agricultural activities that involve the use of fertilizers and animal manures are major sources of nitrate contamination. Several processes are currently available that can effectively remove nitrate from raw water. Systems that are suitable for small rural communities include: reverse osmosis, ion exchange, and electrodialysis. However, disposal of the reject water or brine water is a major expense and environmental issue that is associated with all three systems because these systems simply move the nitrate from the raw water and concentrate it in the reject water or brine. Several emerging systems are under development that convert nitrate to harmless nitrogen gas. These include biological denitrification systems and catalytic systems. The ability of these systems to convert the nitrate to nitrogen gas is a major advantage. Above ground denitrification reactors might be used to provide nitrate free water to rural communities in the not too distant future. Reverse osmosis, ion exchange, and distillation can be used in home systems to remove nitrate from raw water. Reverse osmosis and distillation are small point of use systems that provide water for cooking and drinking. With these systems the small volume of reject water generated would be flushed to the septic system and would not normally present a disposal problem. A more important concern might be the volume of water used by some of the systems. Some emerging systems might prove suitable for home or farm use in the future. Biobarriers might be used to protect a well from a contaminated aquifer or to protect an aquifer used for drinking water from a source of nitrate pollution. |
