Twomey Kelly M, Stillwell Ashlynn S, Webber Michael E
Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA.
J Environ Monit. 2010 Jan;12(1):218-24. doi: 10.1039/b913137j. Epub 2009 Oct 20.
Increases in corn cultivation for biofuels production, due to the Energy Independence and Security Act of 2007, are likely to lead to increases in nitrate concentrations in both surface and groundwater resources in the United States. These increases might trigger the requirement for additional energy consumption for water treatment to remove the nitrates. While these increasing concentrations of nitrate might pose a human health concern, most water resources were found to be within current maximum contaminant level (MCL) limits of 10 mg L(-1) NO(3)-N. When water resources exceed this MCL, energy-intensive drinking water treatment is required to reduce nitrate levels below 10 mg L(-1). Based on prior estimates of water supplies currently exceeding the nitrate MCL, we calculate that advanced drinking water treatment might require an additional 2360 million kWh annually (for nitrate affected areas only)--a 2100% increase in energy requirements for water treatment in those same areas--to mitigate nitrate contamination and meet the MCL requirement. We predict that projected increases in nitrate contamination in water may impact the energy consumed in the water treatment sector, because of the convergence of several related trends: (1) increasing cornstarch-based ethanol production, (2) increasing nutrient loading in surface water and groundwater resources as a consequence of increased corn-based ethanol production, (3) additional drinking water sources that exceed the MCL for nitrate, and (4) potentially more stringent drinking water standards for nitrate.
根据2007年的《能源独立与安全法案》，用于生物燃料生产的玉米种植面积增加，这可能会导致美国地表水和地下水资源中的硝酸盐浓度上升。这些增加可能会引发对用于去除硝酸盐的水处理额外能源消耗的需求。虽然这些不断增加的硝酸盐浓度可能会引发对人类健康的担忧，但大多数水资源仍在目前10毫克/升（以氮计）的最大污染物水平（MCL）限值内。当水资源超过这一MCL时，就需要进行能源密集型的饮用水处理，将硝酸盐水平降至10毫克/升以下。根据先前对目前超过硝酸盐MCL的供水情况的估计，我们计算得出，先进的饮用水处理每年可能需要额外增加2.36亿千瓦时（仅针对受硝酸盐影响的地区）——这些地区水处理的能源需求增加了2100%——以减轻硝酸盐污染并满足MCL要求。我们预测，预计水中硝酸盐污染的增加可能会影响水处理部门的能源消耗，这是由于几个相关趋势的共同作用：（1）基于玉米淀粉的乙醇产量增加；（2）由于基于玉米的乙醇产量增加，地表水和地下水资源中的养分负荷增加；（3）超过硝酸盐MCL的额外饮用水源；（4）可能对硝酸盐制定更严格的饮用水标准。
