Replicable simulation of distal hot water premise plumbing using convectively-mixed pipe reactors
Replicable simulation of distal hot water premise plumbing using convectively-mixed pipe reactors
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DOI：
10.1371/journal.pone.0238385
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发表时间：
2020-09
期刊：
影响因子：
3.7
通讯作者：
M. S. Spencer;Abraham Cullom;W. Rhoads;A. Pruden;Marc A Edwards
中科院分区：
文献类型：
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作者：
M. S. Spencer;Abraham Cullom;W. Rhoads;A. Pruden;Marc A Edwards
缺乏在实验室规模下真实模拟热水前提管道条件的可复制测试系统是识别支持机会性病原体（OP）生长和阻止疾病传播的机会的关键因素的障碍。在这里，我们开发了对流混合管道反应器（CMPR）作为一个简单的可重复系统，由现成的管道材料组成，通过自然对流自混合，并能够并行测试多个，复制和现实的前提管道条件。进行了一项为期10周的验证研究，将三种管道材料（PVC、PVC-铜和PVC-铁;各n = 18）与无对流混合的停滞对照管道（各n = 3）进行了比较。发现重复CMPR产生一致的水化学作为管道材料的函数，到第9周差异变得不太明显。温度是已知控制OP生长的首要因素，在所有54个CMPR中保持一致，变异系数<2%。由于腐蚀，PVC-铁（1.96 ± 0.29 mg/L）中的溶解氧（DO）仍低于PVC（5.71 ± 0.22 mg/L）或PVC-铜（5.90 ± 0.38 mg/L）CMPR，如预期。此外，PVC-铁CMPR中的DO是在相应的停滞管中观察到的DO（6.03 ± 0.33 mg/L）的33%，证明了内部对流混合在刺激腐蚀和微生物呼吸中的重要作用。16 S rRNA基因扩增子测序表明，无论是散装水（Padonis = 0.001，R2 = 0.222，Pbetadis = 0.785）和生物膜（Padonis = 0.001，R2 = 0.119，Pbetadis = 0.827）微生物群落CMPR与停滞的管道之间的差异，与创建一个独特的生态位。总体而言，CMPR可以提供比先前研究中常用的反应堆更真实的前提管道某些方面的模拟，其成本，空间和大型试验规模钻机的水需求仅为一小部分。
A lack of replicable test systems that realistically simulate hot water premise plumbing conditions at the laboratory-scale is an obstacle to identifying key factors that support growth of opportunistic pathogens (OPs) and opportunities to stem disease transmission. Here we developed the convectively-mixed pipe reactor (CMPR) as a simple reproducible system, consisting of off-the-shelf plumbing materials, that self-mixes through natural convective currents and enables testing of multiple, replicated, and realistic premise plumbing conditions in parallel. A 10-week validation study was conducted, comparing three pipe materials (PVC, PVC-copper, and PVC-iron; n = 18 each) to stagnant control pipes without convective mixing (n = 3 each). Replicate CMPRs were found to yield consistent water chemistry as a function of pipe material, with differences becoming less discernable by week 9. Temperature, an overarching factor known to control OP growth, was consistently maintained across all 54 CMPRs, with a coefficient of variation <2%. Dissolved oxygen (DO) remained lower in PVC-iron (1.96 ± 0.29 mg/L) than in PVC (5.71 ± 0.22 mg/L) or PVC-copper (5.90 ± 0.38 mg/L) CMPRs as expected due to corrosion. Further, DO in PVC-iron CMPRs was 33% of that observed in corresponding stagnant pipes (6.03 ± 0.33 mg/L), demonstrating the important role of internal convective mixing in stimulating corrosion and microbiological respiration. 16S rRNA gene amplicon sequencing indicated that both bulk water (Padonis = 0.001, R2 = 0.222, Pbetadis = 0.785) and biofilm (Padonis = 0.001, R2 = 0.119, Pbetadis = 0.827) microbial communities differed between CMPR versus stagnant pipes, consistent with creation of a distinct ecological niche. Overall, CMPRs can provide a more realistic simulation of certain aspects of premise plumbing than reactors commonly applied in prior research, at a fraction of the cost, space, and water demand of large pilot-scale rigs.