Collaborative Research: Influence of drinking water chemical composition on biofilm properties and decay of disinfectant residual: an experimental and modeling study

自来水经过配水系统的处理和监测，通常被认为是安全的。然而，我们所依赖的供水基础设施最近发生了几起故障，这突显了更好地了解和监测国家水质的必要性。最近的研究表明，从饮用水处理厂的源头到家庭的水龙头，水质可能会恶化。这项研究的重点是建筑内部的“前提管道”，这是水分配系统中最不为人所知和监测的部分。住宅管道在分配系统中具有最高的表面体积比，使其容易受到管道表面化学和生物反应的影响。此外，水往往会在小管道中滞留数日，导致剩余消毒剂活性丧失，并导致病原体在管道表面生物膜中生长。该项目将确定如何减少消毒剂的腐烂，有毒消毒剂副产品的形成，以及在前提管道表面生长的生物膜中病原体的生长。这将通过使用消毒剂的控制实验和生物膜中存在的微生物的分子水平表征来实现。结果将与饮用水行业、水监管机构和其他利益相关者分享，以制定确保家庭饮用水安全的最佳管理做法。提出了一项系统的研究，以了解风险是如何、何时以及在何处发生的。本研究基于以下假设：（H1）饮用水化学成分控制前提管道生物膜的多孔结构；（H2）这些生物膜的特性控制了生物膜和水相之间消毒剂的质量交换，从而控制了消毒剂的残留浓度；（H3）在饮用水中生长的实验室生物膜将具有从这些来源供应的室内管道网络中发生的生物膜的扩散和反应特性。一个合作研究项目将通过一个多阶段的研究项目来检验这些假设。首先，在PEX和PVC消毒剂浓度降低的停滞条件下，生物质生长，常见的管道材料使用自来水添加抗结垢和/或抗腐蚀化学物质来模拟处理过的饮用水。H1将通过基于从这些不同水域生长的生物膜的光学相干断层扫描分析生物膜基质的三维多孔结构来测试。氢气将通过定量消毒剂与生物膜的相互作用，通过片状和管道段尺度的反应输送实验和建模来测试。在伊利诺伊大学和华盛顿州立大学的建筑规模实验中，H3将在不同的停滞时间下通过定量的游离氯衰变和消毒剂副产物的形成来进行测试。这项研究的成功完成将改变我们对室内管道中生物膜生长和消毒剂化学的认识，并帮助监管机构和其他利益相关者更好地管理供水系统，以保护人类健康。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Tap water treated and monitored by the water distribution system has generally thought to be safe. However, several recent failures of water infrastructure that we rely on for this safety have highlighted the need to better understand and monitor the Nation's water quality. Recent research has shown that water quality can deteriorate from the source at the drinking water treatment plant to the taps in homes. A focus of this research is on in-building "premise plumbing", the least understood and monitored part of the water distribution system. Premise plumbing has the highest surface-to-volume ratios in the distribution system, making it susceptible to pipe surface chemical and biological reactions. In addition, water can often sit stagnant in small pipes for days, resulting in loss of residual disinfectant activity and resulting pathogen growth in pipe surface biofilms. This project will determine how to reduce the decay of disinfectant, the formation of toxic disinfectant byproducts, and the growth of pathogens in biofilms that grow on premise plumbing surfaces. This will be achieved by controlled experiments with disinfectants and molecular level characterization of the microbes present in the biofilm. Results will be shared with the drinking water industry, water regulators, and other stakeholders to develop best management practices for ensuring the safety of home drinking water.A systematic study is proposed to understand how, when, and where risk occurs in premise plumbing. The research is based on the following hypotheses: (H1) drinking water chemical constituents control the porous structure of premise plumbing biofilms; (H2) these biofilm properties control the mass exchange of disinfectant between the biofilm and bulk aqueous phases and consequently the residual concentrations of disinfectants; and (H3) laboratory biofilms grown in the presence of drinking water will have diffusion and reaction properties of biofilms occurring in premise plumbing networks supplied from those sources. A collaborative research program will test these hypotheses through a multi-stage research program. First, biomass growth under stagnant conditions with depleted disinfectant concentrations on PEX and PVC, common premise plumbing materials using tap water amended with anti-scaling and/or anti-corrosion chemicals to simulate treated drinking water. H1 will be tested by analyzing 3D porous structure of biofilm matrix based on optical coherence tomography of biofilms grown from these different waters. H2 will be tested by quantifying the interaction of disinfectant with biofilm via coupon- and pipe-section scale reactive transport experiments and modeling. H3 will be tested by quantifying free chlorine decay and formation of disinfectant byproducts in building scale experiments at the University of Illinois and Washington State University under different stagnation times. Successful completion of this research will transform our knowledge of biofilm growth and disinfectant chemistry in premise plumbing and help regulators and other stakeholders better manage water supply systems to protect human health.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.