Oates Peter M, Shanahan Peter, Polz Martin F
Department of Civil and Environmental Engineering, Parsons Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Water Res. 2003 Jan;37(1):47-54. doi: 10.1016/s0043-1354(02)00241-5.
Haiti and other developing countries do not have sufficient meteorological data to evaluate if they meet the solar disinfection (SODIS) threshold of 3-5 h of solar radiation above 500 W/m2, which is required for adequate microbial inactivation in drinking water. We have developed a mathematical model based on satellite-derived daily total energies to simulate monthly mean, minimum, and maximum 5-h averaged peak solar radiation intensities. This model can be used to assess if SODIS technology would be applicable anywhere in the world. Field measurements were made in Haiti during January 2001 to evaluate the model and test SODIS efficacy as a point-of-use treatment option. Using the total energy from a measured solar radiation intensity profile, the model recreated the intensity profile with 99% agreement. NASA satellite data were then used to simulate the mean, minimum, and maximum 5-h averaged peak intensities for Haiti in January, which were within 98.5%, 62.5%, and 86.0% agreement with the measured values, respectively. Most of the discrepancy was attributed to the heterogeneous nature of Haiti's terrain and the spatial resolution of the NASA data. Additional model simulations suggest that SODIS should be effective year-round in Haiti. Actual SODIS efficacy in January was tested by the inactivation of total coliform, E. coli, and H2S-producing bacteria. Exposure period proved critical. One-day exposure achieved complete bacterial inactivation 52% of the time, while a 2-day exposure period achieved complete microbial inactivation 100% of the time. A practical way of providing people with cold water every morning that has undergone a 2-day exposure would be to rotate three groups of bottles every morning, so two groups are out in the sun and one is being used for consumption.
海地和其他发展中国家没有足够的气象数据来评估它们是否达到了太阳能消毒（SODIS）所需的阈值，即500瓦/平方米以上的太阳辐射3至5小时，这是饮用水中微生物充分失活所必需的。我们基于卫星获取的每日总能量开发了一个数学模型，以模拟月平均、最低和最高的5小时平均峰值太阳辐射强度。该模型可用于评估SODIS技术在世界任何地方是否适用。2001年1月在海地进行了实地测量，以评估该模型并测试SODIS作为一种现场使用的处理选项的效果。利用测量的太阳辐射强度曲线的总能量，该模型重建了强度曲线，吻合度达99%。然后利用美国国家航空航天局（NASA）的卫星数据模拟了海地1月份的平均、最低和最高5小时平均峰值强度，分别与测量值的吻合度为98.5%、62.5%和86.0%。大部分差异归因于海地地形的不均匀性和NASA数据的空间分辨率。额外的模型模拟表明，SODIS在海地全年都应有效。1月份通过总大肠菌群、大肠杆菌和产硫化氢细菌的失活测试了实际的SODIS效果。暴露时间证明至关重要。一天的暴露有52%的时间能使细菌完全失活，而两天的暴露时间能100%地使微生物完全失活。每天早上为人们提供经过两天暴露的冷水的一种实用方法是每天早上轮换三组瓶子，这样两组放在阳光下，一组用于饮用。
