Characterization and Significance of Sub-Visible Particles and Colloids in a Submerged Anaerobic Membrane Bioreactor (SAnMBR)

The distribution, composition and morphological structure of subvisible particles and colloids (0.01–10 μm) in the supernatant of a lab-scale submerged anaerobic membrane bioreactor (SAnMBR), and their role in membrane fouling, was investigated. Photometric analysis showed that the supernatant and membrane foulants were dominated by particles and colloids (0.45–10 μm), which accounted for over 90% of the total organics (proteins and polysaccharides). Excitation–emission matrix (EEM) fluorescence spectra and monosaccharide analysis showed that these particles and colloids were rich in fluorescent proteins, rhamnose, ribose and arabinose, all of which could be related to cellular and extracellular substances. Fluorescence and scanning electron microscopy confirmed the presence of bacterial cells in/on the subvisible particles and colloids. The microparticles (5–10 μm) were primarily composed of Streptobacilli and/or filamentous bacteria in the form of microcolonies, while the submicrometer particles and colloids (1–5 μm and 100 kDa-1 μm) had more free/single cocci and bacilli. The ratio of live/dead cells varied in different size-fractions, and the particles (1–10 μm) contained more live cells compared with the colloids (100 kDa-1 μm). Our findings suggest that bacterial cells in/on the particles and colloids could have an important effect on fouling in SAnMBRs as they represent pioneering species attaching to membranes to form fouling layers/biofilm. Such insights reveal that previous foulant-characterization studies in MBRs tended to overestimate organic fouling, while the biofouling induced by these bacteria in/on the particles and colloids was overlooked

Data_Sheet_1_Characterization of sewage quality and its spatiotemporal variations in a small town in Eastern Guangdong, China.PDF

The domestic sewage in rural areas of South China is characterized by a relatively low concentration of organic pollutants; however, the factors causing this have not been carefully examined. This study conducted a comprehensive survey on two sewer networks in a small town of Eastern Guangdong, China, via grab water sampling at a frequency of once every 2 weeks lasting for 1 year. The sewage quality showed significant variations across the systems, while a gradual decrease in the concentrations of chemical oxygen demand (COD), total nitrogen (TN) and phosphorus (TP) from the upper to lower reaches of sewers could be observed. Storm events could have a flushing effect on TP in the upper reach of sewers, but a dilution effect on COD and TN in flat terrains. The diurnal pattern of sewage was largely impacted by the position of the manholes and water consumption difference between holidays and normal days. Both COD/TN and TN/TP ratios of the sewage showed a lognormal distribution dominating in the range of 2.0–3.0 and ~10.0, respectively. The low ratio of COD/TN in the morning discharge peak could be attributed to the wide use of septic tanks in the area, while groundwater infiltration played more important roles in the basal flow conditions. This study could serve as a basic reference for designing and managing sewage infrastructure in rural areas of South China and highlights that prevention of groundwater infiltration is crucial to improve the efficiency of sewage infrastructure in high water table areas.</p