Yan Dazhuang, Bai Zhihui, Mike Rowan, Gu Likun, Ren Shumei, Yang Peiling
College of Water Conservancy and Civil Engineering, China Agricultural University, Beijing 100083, China.
J Environ Sci (China). 2009;21(6):834-41. doi: 10.1016/s1001-0742(08)62349-9.
Using reclaimed wastewater for crop irrigation is a practical alternative to discharge wastewater treatment plant effluents into surface waters. However, biofouling has been identified as a major contributor to emitter clogging in drip irrigation systems distributing reclaimed wastewater. Little is known about the biofilm structure and its influence on clogging in the drip emitter flow path. This study was first to investigate the microbial characteristics of mature biofilms present in the emitters and the effect of flow path structures on the biofilm microbial communities. The analysis of biofilm matrix structure using a scanning electron microscopy (SEM) revealed that particles in the matrix of the biofilm coupled extracellular polysaccharides (EPS) and formed sediment in the emitter flow path. Analysis of biofilm mass including protein, polysaccharide, and phospholipid fatty acids (PLFAs) showed that emitter flow path style influenced biofilm community structure and diversity. The correlations of biofilm biomass and discharge reduction after 360 h irrigation were computed and suggest that PFLAs provide the best correlation coefficient. Comparatively, the emitter with the unsymmetrical dentate structure and shorter flow path (Emitter C) had the best anti-clogging capability. By optimizing the dentate structure, the internal flow pattern within the flow path could be enhanced as an important method to control the biofilm within emitter flow path. This study established electron microscope techniques and biochemical microbial analysis methods that may provide a framework for future emitter biofilm studies.
将再生水用于作物灌溉是一种切实可行的替代方案，可避免将污水处理厂的废水排放到地表水中。然而，生物污垢已被确认为是在分配再生水的滴灌系统中导致滴头堵塞的主要因素。关于生物膜结构及其对滴头流道堵塞的影响，人们所知甚少。本研究首次调查了滴头中成熟生物膜的微生物特性以及流道结构对生物膜微生物群落的影响。使用扫描电子显微镜（SEM）对生物膜基质结构进行分析后发现，生物膜基质中的颗粒与细胞外多糖（EPS）结合，并在滴头流道中形成沉积物。对生物膜物质（包括蛋白质、多糖和磷脂脂肪酸（PLFA））的分析表明，滴头流道样式会影响生物膜群落结构和多样性。计算了灌溉360小时后生物膜生物量与流量减少之间的相关性，结果表明PLFA的相关系数最佳。相比之下，具有不对称齿状结构且流道较短的滴头（滴头C）具有最佳的抗堵塞能力。通过优化齿状结构，可以增强流道内的内部流动模式，这是控制滴头流道内生物膜的一种重要方法。本研究建立了电子显微镜技术和生化微生物分析方法，可为未来滴头生物膜研究提供一个框架。
