Salih Fadhil M
Department of Clinical and Biomedical Physics, College of Medicine and Health Sciences, Sultan Qaboos University, P.O. Box 35, Al-Khod 123 Sultanate of Oman.
Water Res. 2003 Sep;37(16):3921-7. doi: 10.1016/S0043-1354(03)00307-5.
A mathematical model was formulated that will facilitate the prediction of solar disinfection by analyzing the effect of sunlight exposure (x(1)) and the load of bacterial contamination (x(2)), as predictor variables, on the efficiency of solar disinfection (y). Aliquots of 0.1 ml containing average numbers of E. coli, ranging between 1 and 5 x 10(3)cells/ml raw water, were introduced into each of the 96 wells of polystyrene microtitre plates. Plates, with the lid on, were exposed to sunlight for varying exposures ranging between 1.04 x 10(3) and 8.40 x 10(3)kJ m(-2). Double strength nutrient broth was then added. After 48 h incubation wells containing visible contamination were considered as containing one cell or more that survived the exposure. Data showed that disinfection is dependent both on the load of bacterial contamination and sunlight exposure. This relationship is characterized by curves having shoulders followed by a steep decline and then tailing off in an asymptotic fashion. The shoulder size increased with the increase of the contamination load, however, the slope remains the same. Statistical analysis indicates a positive correlation among the variables (R(2) = 0.893); the mathematical model, y=1-(1-e(-kx(1)))(x(2)), represents the relationship, with k being the solar inactivation constant. The exposure required to produce a given decontamination level can be predicted using the equation: x(1)=-1/kln[1-(1-y)(-1/x(2))]e(-micro/rho.m/A), where micro is the linear attenuation coefficient (m(-1)), rho is the density, m is the mass and A is the area of the exposed part of the sample. The predictor variables (x(1), x(2)) strongly influence the efficiency of solar disinfection, which can be predicted using the suggested mathematical model. The present data provides a means to predict the efficiency of solar disinfection as an approach to improve the quality of drinking water mainly in developing countries with adequate sunshine all year-round.
通过分析阳光照射量（x(1)）和细菌污染负荷（x(2)）这两个预测变量对太阳能消毒效率（y）的影响，建立了一个数学模型，以促进对太阳能消毒的预测。将含有平均数量大肠杆菌（每毫升原水中大肠杆菌数量在1至5×10(3)个细胞之间）的0.1毫升等分试样，分别加入到聚苯乙烯微量滴定板的96个孔中。盖上盖子的滴定板在阳光下暴露不同时间，照射量在1.04×10(3)至8.40×10(3)kJ m(-2)之间。然后加入双倍强度的营养肉汤。培养48小时后，含有可见污染物的孔被视为含有一个或多个在照射后存活的细胞。数据表明，消毒既取决于细菌污染负荷，也取决于阳光照射量。这种关系的特征是曲线先有一个平台期，然后急剧下降，最后以渐近方式逐渐减弱。平台期的大小随着污染负荷的增加而增大，然而斜率保持不变。统计分析表明变量之间存在正相关（R(2)=0.893）；数学模型y=1-(1-e(-kx(1)))(x(2))代表了这种关系，其中k是太阳能灭活常数。使用方程x(1)=-1/kln[1-(1-y)(-1/x(2))]e(-micro/rho.m/A)可以预测产生给定去污水平所需的照射量，其中micro是线性衰减系数（m(-1)），rho是密度，m是质量，A是样品暴露部分的面积。预测变量（x(1)，x(2)）强烈影响太阳能消毒效率，可使用所建议的数学模型进行预测。目前的数据提供了一种预测太阳能消毒效率的方法，作为改善主要是全年阳光充足的发展中国家饮用水质量的一种途径。
