Collaborative Research: Influence of Drinking Water Chemical Composition on Biofilm Properties and Decay of Disinfectant Residual: An Experimental and Modeling Study

经配水系统处理和监测的自来水通常被认为是安全的。然而，最近几次我们所依赖的供水基础设施的故障突出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。这项研究的重点是在建筑物内的“前提管道”，最不了解和监测的一部分，供水系统。管道在分配系统中具有最高的表面积与体积比，使其容易受到管道表面化学和生物反应的影响。此外，水通常可以在小管道中停滞数天，导致残留消毒剂活性的损失和导致管道表面生物膜中的病原体生长。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，以及在房屋管道表面生长的生物膜中病原体的生长。这将通过消毒剂的对照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，以制定最佳管理实践，确保家庭饮用水的安全。本研究基于以下假设：（H1）饮用水化学成分控制房屋管道生物膜的多孔结构;（H2）这些生物膜特性控制生物膜和主体水相之间的消毒剂质量交换，从而控制消毒剂的残留浓度;和（H3）在饮用水存在下生长的实验室生物膜将具有在由这些来源供应的房屋管道网络中发生的生物膜的扩散和反应性质。合作研究计划将通过多阶段研究计划来测试这些假设。首先，在PEX和PVC上具有耗尽的消毒剂浓度的停滞条件下的生物质生长，PEX和PVC是使用用防垢和/或防腐蚀化学品修正的自来水来模拟经处理的饮用水的常见前提管道材料。将通过基于从这些不同沃茨生长的生物膜的光学相干断层扫描分析生物膜基质的3D多孔结构来测试H1。将通过试样和管段规模的反应性运输实验和建模，通过量化消毒剂与生物膜的相互作用来测试H2。H3将通过在伊利诺伊大学和华盛顿州立大学的建筑规模实验中在不同停滞时间下量化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建筑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NSF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.