Integrated disinfection strategies for treatment of drinking water

在饮用水分配系统中，细菌和其他病原体往往聚集在管道表面，否则称为生物膜的形成。消毒是尽量减少这种形成的关键步骤，这种形成有可能导致致病微生物的增加。由于不同的原因，供应商通常会在处理过程中联合使用一级和二级消毒剂，尽管这是一种广泛使用的做法，但很少强调消毒剂之间可能产生的协同效益。当消毒剂“协同工作”时，协同效益将包括增强减少分配系统中细菌的能力。很少有专门研究协同作用的研究发表，特别是使用紫外线处理饮用水。兰德博士之前的工作已经在实验室测试中证实，紫外线和氯基消毒剂之间存在协同作用，可以去除大肠杆菌。通过模拟分配系统进行的实地研究也发现，有可能产生协同效益。为了计算协同作用，采用了Koivunen等人（2005）提出的概念，该概念指出，当联合消毒策略的去除量大于单独使用每种消毒剂的去除量之和时，就存在协同作用。虽然这是一个有用的公式，但它只依赖于消毒剂的功效。因此，很难应用于长期的研究中，因为管道材料、水质、营养物供应等问题对生物膜的形成会产生严重的影响。然而，如果协同作用可以实际量化，这可能导致供应商能够在不增加消毒剂剂量的情况下减少更多的致病微生物。本研究的目的是调查不同条件下消毒剂之间协同作用的潜力，并开发一个模型来量化协同作用，以便公用事业公司可以在没有长期实验和试点研究的情况下模拟他们的系统。

In drinking water distribution systems, bacteria and other pathogens tend to cluster on pipe surfaces, otherwise known as the formation of biofilm. Disinfection is a key step for minimizing this formation, which has the potential to lead to an increase in pathogenic microorganisms. Suppliers will often utilize primary and secondary disinfectants in combination in the treatment process for different reasons, and although this is a widely used practice little emphasis has been placed on the potential for synergistic benefits between disinfectants. Synergistic benefits would include an enhanced ability to reduce bacteria in distribution systems when the disinfectants "work together". There have been few studies published that were designed specifically to investigate synergy, especially using UV light for the treatment of drinking water. Previous work done by Dr. Rand has established in laboratory tests that synergy exits between UV light and chlorine-based disinfectants for removing Escherichia coli (E. coli). It was also found in field studies through simulating distribution systems that there was potential for synergistic benefits. To calculate synergy, a concept presented by Koivunen et al. (2005) was adopted, which stated that synergy was present when the removal of a combined disinfection strategy was greater than the sum of removals achieved by each disinfectant alone. Although this is a useful equation, it relies on disinfectant efficacy alone. Therefore, it is difficult to apply in long-term studies, where pipe material, water quality, nutrient supply and other issues would play a serious role in the formation of biofilm. However, if synergy could be quantified realistically, this could lead to suppliers being able to reduce more pathogenic microorganisms without increasing disinfectant dosages. The purpose of this research is to investigate the potential for synergy between disinfectants under different conditions and to develop a model to quantify synergy so that utilities might be able to simulate their systems without long-term bench and pilot studies.