Adapting to life in a changing climate: optimizing water treatment processes

许多饮用水处理厂(WTP)现在使用膜来去除有害微生物。气候变化预计将增加污水处理厂与藻类和蓝藻相关的问题，包括更多的味道和气味事件，更多的膜污染和蓝藻毒素的释放。溶气浮选是一种去除藻类和蓝藻的有效工艺，但仅在部分污水处理厂得到应用。活性碳吸附过程是去除味道和气味化合物、蓝藻毒素和其他微量污染物的最佳技术之一；由于热再生过程中AC质量损失5%至15%，目前正在开发替代吸附剂，如NYEX。这项提案的目标是通过以下举措帮助改进WTP并使其更具应对气候变化的能力。首先，开发一种新的实验室规模的DAF测试装置，并对不同的水域进行测试，包括在藻类水华期间的一次测试。第二，比较DAF和压载沉淀法在处理藻类水华期间的水的效率。申请人的团队发现，对于渥太华河水，采用DAF预处理减少膜污染优于采用沉淀预处理。第三，确定膜系统类型和处理水的类型是否会影响DAF的优势。计划中的实验包括在藻类大量繁殖条件下进行测试。第四，继续研究NYEX吸附/电化学再生系统作为活性碳吸附去除痕量污染物的替代方案。具体地说，申请人的团队将确定NYEX去除微量污染物(如杀虫剂和蓝藻毒素)的能力是否比活性碳受到天然有机物存在的影响较小，这是活性碳的一个缺点。所有这些举措都将有助于设计水处理系统，使其能够在未来更频繁的藻类/蓝藻水华中发挥更好的作用，并避免像2014年8月俄亥俄州托莱多为期3天的“禁酒令”那样的情况。

Many drinking water treatment plants (WTPs) now use membranes to remove harmful microorganisms. Climate change is expected to increase algal and cyanobacterial-related problems at WTPs including greater taste and odour incidents, greater fouling of membranes and the release of cyanobacterial toxins. Dissolved air floatation (DAF) is an effective process for the removal of algae and cyanobacteria, but it used in only some WTPs. Activated carbon adsorption processes are one of the best technologies for the removal of taste and odour compounds, cyanobacterial toxins and other trace contaminants; due to the 5 to 15% AC mass losses during thermal regeneration, alternative adsorbents, such as NYEX, are currently being developed. The objective of this proposal is to help improve WTPs and make them more climate-change resilient through the following initiatives. First, to develop a new bench-scale DAF testing unit, and test it for different waters, including one during an algal bloom. Second, to compare the efficiency of DAF with that of ballasted sedimentation, a competing separation process, for the treatment of water during algal blooms. The applicant's team has found that for Ottawa River water, to reduce membrane fouling pretreatment by DAF was superior to pretreatment by sedimentation. Third, to confirm if this DAF superiority is impacted by the membrane system type and the type of water treated. Planned experiments include testing during algal bloom conditions. Fourth, to continue researching the NYEX adsorption/electrochemical regeneration system as an alternative to activated carbon adsorption for the removal of trace contaminants. Specifically, the applicant's team will determine if NYEX's capacity to remove trace contaminants (such as pesticides and cyanobacterial toxins) is less impacted than that of activated carbon by the presence of natural organic matter, which is a drawback of activated carbon. All of these initiatives will help design water treatment systems that can perform better under the more frequent algal/cyanobacterial blooms expected in the future, and avoid situations like the 3-day “no drink order` in Toledo, OH in August 2014.