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首页> 外文期刊>Journal of Environmental Science and Health >Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality
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Assessment of the extent of bacterial growth in reverse osmosis system for improving drinking water quality

机译：评估反渗透系统中细菌的生长程度，以改善饮用水质量

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This study was carried out to assess reverse osmosis (RO) treatment efficacy of drinking water in terms of biological stability in the distribution system. Two flat-sheet RO membranes were used in this study. Experiments were designed to investigate the growth of biofilm and bulk phase bacteria for the RO-treated water flowing through a model distribution system under controlled conditions without disinfectants. RO membranes improved the water quality of drinking water in terms of inorganic, organic and bacterial contents. Organic matter including the fraction available for microbes was efficiently removed by the RO membranes tested. More than 99% of bacterial cells in the tap water was retained by the RO membranes, leaving <50 cells/mL in the permeate water. In spite of the low nutrient contents and few cells in the RO permeates, monitoring of the model distribution systems receiving the RO permeates showed that remarkable biofilm accumulation and bulk cell growth occurred in the RO permeate water. In quasi-steady state, the total cell numbers in the biofilm and bulk water were of order 10~3 cells/cm~2 and 10~3 cells/mL, respectively, which were about 2 orders of magnitude lower than those grown in the tap water produced from conventional water treatment. The culturable heterotrophic bacteria constituted a significant part of the total cells (20.7-32.1% in biofilms and 21.3-46.3% in bulk waters). Biofilm maximum density and production rate were of the order 10~4 cells/cm~2 and 10~2 cells/cm~2/day, respectively. The specific cell growth rate of bacteria in the biofilms was found to be much lower than those in the bulk waters (0.04-0.05 day~(-1) versus 0.28-0.36 day~(-1)). The overall specific cell growth rate which indicates the growth potential in the whole system was calculated as 0.07-0.08 day~(-1), representing a doubling time of 9.1-10.1 days. These observations can be indicative of possibilities for bacterial growth in the RO permeate water with easily assimilable organic carbon concentrations below values proposed for biostability. RO permeate water does not appear to be biologically stable water. Therefore, efforts to minimize bacterial growth in the RO permeate water and in the distribution system must consider post-disinfection.
机译：进行这项研究以评估饮用水在分配系统中的生物稳定性方面的反渗透（RO）处理功效。在这项研究中使用了两个平板RO膜。设计实验以研究在没有消毒剂的可控条件下，经RO处理的水流过模型分配系统时生物膜和体相细菌的生长。反渗透膜从无机，有机和细菌含量方面改善了饮用水的水质。通过测试的反渗透膜可有效去除包括微生物可利用部分在内的有机物。自来水中超过99％的细菌细胞被RO膜截留，而渗透水中的细菌细胞数量仍少于50个/ mL。尽管RO渗透物中的养分含量低且细胞很少，但对接收RO渗透物的模型分布系统的监控显示，RO渗透水中发生了显着的生物膜积累和大量细胞生长。在准稳态下，生物膜和大量水中的总细胞数分别为10〜3个细胞/ cm〜2和10〜3个细胞/ mL，比生长在水中的细胞数少约2个数量级。由常规水处理产生的自来水。可培养的异养细菌占总细胞的很大一部分（生物膜占20.7-32.1％，散装水占21.3-46.3％）。生物膜的最大密度和生产率分别约为10〜4个细胞/ cm〜2和10〜2个细胞/ cm〜2 /天。发现生物膜中细菌的比细胞生长速率远低于散装水中的细菌生长速率（0.04-0.05天〜（-1）比0.28-0.36天〜（-1））。计算表明整个系统中的生长潜力的总比细胞生长速率为0.07-0.08天〜（-1），表示倍增时间为9.1-10.1天。这些观察结果可以表明，在RO渗透水中细菌生长的可能性很大，而有机碳的浓度容易低于可吸收的生物稳定性值。 RO渗透水似乎不是生物学稳定的水。因此，为尽量减少反渗透水和分配系统中细菌的生长而进行的努力必须考虑消毒后的情况。

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