School of Environmental Science & Engineering, Tianjin University, Tianjin 300350, China; College of Water Resources and Civil Engineering, China Agricultural University, Beijing 100083, China.
School of Environmental Science & Engineering, Tianjin University, Tianjin 300350, China.
Sci Total Environ. 2022 Aug 15;834:155289. doi: 10.1016/j.scitotenv.2022.155289. Epub 2022 Apr 18.
Biofilm formation in reclaimed water (RW) distribution systems presents significant technical challenges to RW utilization. Two main technologies to control biofilm formation, microbial antagonism (MA) and electrochemical oxidation (EO), are not yet widely used in drip irrigation systems (DIS) and their mechanisms of action need further clarification. In this study, we first showed that the MA and EO treatments reduced biofilm formation by about 62% and 68%, respectively, and extracellular polymeric substance (EPS) content by 14% and 49%, respectively, in biofilms compared with raw RW type 1 (R-RW1) in unused pipes, thus effectively improving the performance of DIS. When MA-RW and EO-RW were applied to already clogged systems, the degree of clogging alleviation varied depending on the severity of the original clogging. We recommend adding the antagonist, Bacillus subtilis, to RW at 25% clogging for the maximum effect and to slow the microbial adaptation process. Compared to MA, the recovery effect of EO was slower initially but lasted longer and had a significantly better alleviating effect on severely clogged pipelines. Illumina Mi-SEQ high-throughput sequencing data showed that both MA and EO resulted in a significant decrease in microbial diversity, dynamic changes in bacterial community structure, and disruption of network interaction and network modularity. Meanwhile, both treatments promoted the growth of specific microorganisms, enhanced the interaction between certain microbial components, and improved the efficiency of information, matter, and energy exchange within the modules. In summary, we verified the dredging effect of two strategies on DIS under different water conditions, revealed the differences in their mechanisms of action, and proposed their application scenarios. Our results will help improve the efficiency of RW in agricultural drip irrigation systems and effectively reduce maintenance costs.
再生水（RW）分配系统中的生物膜形成对 RW 的利用提出了重大的技术挑战。控制生物膜形成的两种主要技术，微生物拮抗（MA）和电化学氧化（EO），尚未在滴灌系统（DIS）中广泛应用，其作用机制需要进一步澄清。在本研究中，我们首先表明，与未使用管道中的原始 RW 类型 1（R-RW1）相比，MA 和 EO 处理分别将生物膜中的生物膜形成减少了约 62%和 68%，并分别将细胞外聚合物（EPS）含量减少了 14%和 49%，从而有效地改善了 DIS 的性能。当 MA-RW 和 EO-RW 应用于已经堵塞的系统时，缓解堵塞的程度取决于原始堵塞的严重程度。我们建议在 RW 中添加拮抗剂枯草芽孢杆菌，以在 25%堵塞时达到最佳效果，并减缓微生物适应过程。与 MA 相比，EO 的恢复效果最初较慢，但持续时间更长，对严重堵塞的管道具有更好的缓解效果。Illumina Mi-SEQ 高通量测序数据显示，MA 和 EO 都导致微生物多样性显著降低，细菌群落结构动态变化，以及网络相互作用和网络模块性的破坏。同时，这两种处理方法都促进了特定微生物的生长，增强了某些微生物成分之间的相互作用，并提高了模块内信息、物质和能量交换的效率。总之，我们验证了两种策略在不同水质条件下对 DIS 的疏浚效果，揭示了它们作用机制的差异，并提出了它们的应用场景。我们的研究结果将有助于提高 RW 在农业滴灌系统中的效率，并有效降低维护成本。
