College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao, 266590, China.
J Environ Manage. 2023 Apr 15;332:117371. doi: 10.1016/j.jenvman.2023.117371. Epub 2023 Feb 4.
Alleviating bacterial-induced clogging is of great importance to improve the efficiency of managed aquifer recharge (MAR). Enzymes (lysozyme and alkaline protease) and sodium hypochlorite (NaClO) are common biological and chemical reagents for inhibiting bacterial growth and activity. To investigate the applicability of these reagents to reduce bioclogging, percolation experiments were performed to simulate a weak alkaline recharge water infiltration through laboratory-scale sand columns, with adding 10 mg/L lysozyme, alkaline protease, and NaClO, respectively. The results showed that, with the addition of lysozyme, alkaline protease, and NaClO, the average clogging rates (the reduced percentages of relative saturated hydraulic conductivity of the sand columns per hour during the percolation experiments) were 0.53%/h, 0.32%/h and 0.06%/h, respectively, which were much lower than that in the control group (0.99%/h). This implied that bioclogging could be alleviated to some extent following the treatments. For further analyzing the mechanisms of the regents on alleviating bioclogging, the bacterial cell amount and extracellular polymeric substances (EPS) concentration were also measured to study the effects of lysozyme, alkaline protease, and NaClO on bacterial growth and EPS secretion. Lysozyme and alkaline protease could disintegrate bacterial EPS by hydrolyzing polysaccharides and proteins, respectively, while they had little effect on the bacterial cell amount. The addition of NaClO significantly decreased the bacterial cell amount (P < 0.05) and thus greatly alleviated bioclogging. Although the lowest average clogging rate was achieved in the NaClO group, it can generate disinfection by-products that are potentially harmful to the environment and human health. Therefore, the biological-based method, i.e., enzyme treatment, could be a promising option for bioclogging control. Our results provide insights for understanding the mechanisms of lysozyme, alkaline protease, and NaClO to alleviate bioclogging, which is of great importance for addressing the clogging problem during MAR activities and achieving groundwater resources sustainable utilization.
减轻细菌引起的堵塞对于提高含水层人工补给（MAR）的效率非常重要。酶（溶菌酶和碱性蛋白酶）和次氯酸钠（NaClO）是常用的抑制细菌生长和活性的生物和化学试剂。为了研究这些试剂在减少生物堵塞方面的适用性，进行了渗流实验，以模拟实验室规模的砂柱中弱碱性补给水的渗透，分别添加了 10mg/L 的溶菌酶、碱性蛋白酶和 NaClO。结果表明，添加溶菌酶、碱性蛋白酶和 NaClO 后，砂柱的平均堵塞率（渗流实验过程中每小时相对饱和水力传导率的降低百分比）分别为 0.53%/h、0.32%/h 和 0.06%/h，远低于对照组的 0.99%/h。这表明处理后可以在一定程度上减轻生物堵塞。为了进一步分析试剂缓解生物堵塞的机制，还测量了细菌数量和胞外聚合物物质（EPS）浓度，以研究溶菌酶、碱性蛋白酶和 NaClO 对细菌生长和 EPS 分泌的影响。溶菌酶和碱性蛋白酶可以分别通过水解多糖和蛋白质来破坏细菌 EPS，而对细菌数量影响不大。NaClO 的添加显著降低了细菌数量（P<0.05），从而大大减轻了生物堵塞。虽然 NaClO 组的平均堵塞率最低，但它会产生潜在有害环境和人类健康的消毒副产物。因此，基于生物的方法，即酶处理，可能是控制生物堵塞的一种有前途的选择。我们的研究结果为理解溶菌酶、碱性蛋白酶和 NaClO 缓解生物堵塞的机制提供了新的见解，这对于解决 MAR 活动中的堵塞问题和实现地下水资源的可持续利用具有重要意义。
