Ranzinger Florian, Matern Maximilian, Layer Manuel, Guthausen Gisela, Wagner Michael, Derlon Nicolas, Horn Harald
Engler-Bunte-Institut, Water Chemistry and Water Technology, Karlsruhe Institute of Technology, Engler-Bunte-Ring 9, 76131, Karlsruhe, Germany.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Process Engineering, CH-8600, Dübendorf, Switzerland.
Water Res X. 2020 Apr 6;7:100050. doi: 10.1016/j.wroa.2020.100050. eCollection 2020 May 1.
The removal or degradation of particulate organic matter is a crucial part in biological wastewater treatment. This is even more valid with respect to aerobic granular sludge and the impact of particulate organic matter on the formation and stability of the entire granulation process. Before the organic part of the particulate matter can be hydrolyzed and finally degraded by the microorganism, the particles have to be transported towards and retained within the granulated biomass. The understanding of these processes is currently very limited. Thus, the present study aimed at visualizing the transport of particulate organic matter into and through an aerobic granular sludge bed. Magnetic Resonance Imaging (MRI) was successfully applied to resolve the different fractions of a granular sludge bed over time and space. Quantification and merging of 3D data sets allowed for a clear determination of the particle distribution within the granular sludge bed. Dextran coated super paramagnetic iron oxide nanoparticles (SPIONs, = nm) served as model particles for colloidal particles. Microcrystalline cellulose particles ( = 1-20 μm) tagged with paramagnetic iron oxide were applied as a reference for toilet paper, which is a major fraction of particulate matter in domestic wastewater. The results were supplemented by the use of real wastewater particles with a size fraction between 28 and 100 μm. Colloidal SPIONs distributed evenly over the granular sludge bed penetrating the granules up to 300 μm. Rinsing the granular sludge bed proved their immobilization. Microcrystalline cellulose and real wastewater particles in the micrometer range accumulated in the void space between settled granules. An almost full retention of the wastewater particles was observed within the first 20 mm of the granular sludge bed. Moreover, the formation of particle layers indicates that most of the micrometer-sized particles are not attached to the biomass and remain mobile. Consequently, these particles are released into the bulk phase when the granulated sludge bed is resuspended.
颗粒有机物的去除或降解是生物废水处理的关键环节。对于好氧颗粒污泥以及颗粒有机物对整个颗粒化过程的形成和稳定性的影响而言，这一点更为重要。在颗粒物质的有机部分能够被微生物水解并最终降解之前，颗粒必须被输送到颗粒状生物质中并保留在其中。目前对这些过程的了解非常有限。因此，本研究旨在可视化颗粒有机物进入和好氧颗粒污泥床并穿过该床的传输过程。磁共振成像（MRI）被成功应用于解析颗粒污泥床在时间和空间上的不同部分。3D数据集的量化和合并使得能够清晰地确定颗粒在颗粒污泥床中的分布。葡聚糖包被的超顺磁性氧化铁纳米颗粒（SPIONs，直径 = 纳米）用作胶体颗粒的模型颗粒。用顺磁性氧化铁标记的微晶纤维素颗粒（直径 = 1 - 20μm）被用作卫生纸的参考，卫生纸是生活污水中颗粒物质的主要部分。通过使用尺寸在28至100μm之间的实际废水颗粒来补充结果。胶体SPIONs均匀分布在颗粒污泥床上，穿透颗粒达300μm。冲洗颗粒污泥床证明了它们的固定化。微米级的微晶纤维素和实际废水颗粒聚集在沉淀颗粒之间的空隙中。在颗粒污泥床的前20mm内观察到几乎完全截留废水颗粒。此外，颗粒层的形成表明大多数微米级颗粒未附着在生物质上且保持可移动性。因此，当颗粒污泥床重新悬浮时，这些颗粒会释放到主体相中。
