Micro-environment characteristics and microbial communities in activated sludge flocs of different particle size

Abstract

h i g h l i g h t s" Microelectrodes and molecular culture-independent techniques were applied. " The micro-environment and bacteria in flocs with different size were detected. " The DO, NH 4 + and NO 3 À concentration were distinct in flocs of different size." The bacterial population was closely related to the micro-environment in flocs.a r t i c l e i n f o b s t r a c tMicroorganisms in activated sludge flocs (ASF) play important roles in the wastewater treatment process. However, the interplay between micro-environmental variation and microbial responses within ASF is poorly understood. In this study, microelectrodes and molecular culture-independent techniques were applied to detect the internal environment, microbial composition, and distribution in flocs with different particle size. Results showed dissolved oxygen (DO) concentrations within the center of the flocs were less than at the surface, and the DO concentration distributions were distinct in flocs of different particle size. With floc particle size increasing from 100 to 250 lm, the DO concentrations in the floc centers decreased 10-55%, respectively, while no distinct change was observed in flocs of less than 100 lm.Similar phenomenon occurred for the distributions of NH 4 + and NO 3 À in flocs. Microbial structure indicated bacterial compositions and distributions were heterogeneous and responded to micro-environment variation in flocs of different particle size.

Performance and fate of organics in a pilot MBR–NF for treating antibiotic production wastewater with recycling NF concentrate

“…S3) in this study, and their closest relative sequences are shown in Table S7. Bacteria belonging to genera Proteobacteria, Firmicutes, and Bacteroidetes were abundant in all the activated sludge processes, which was consistent with Han's (Han et al, 2012) study involving the treatment of municipal wastewater. Fusobacteria, Planctomycetes, and Gammaproteobacteria (including Plesiomonas, Pseudomonas, Vibrio, and Thiothrix) were the most abundant bacteria in this system.…”

Temporal variation of microbial population in acclimation and start-up period of a thermophilic desulfurization biofilter

“…A hybridization solution that contained 5 ng mL À1 of probe was applied to the slide. The FISH procedure was similar to that described by Han (Han et al, 2012). The biomass on the slide was stained with DAPI solution.…”

Temporal variation of microbial population in a thermophilic biofilter for SO 2 removal

“…Facultative anaerobic or anaerobic microorganisms are abundant in environments with an oxygen volume fraction of less than 2% (Lee et al, 2001). With the innovation of microelectrodes, detection of the oxygen distribution in microenvironments is now possible and interesting oxygen microelectrode studies have been performed, including in nitrifying/denitrifying biofilms (Stief et al, 2003) and a single floc (Tsai et al, 2008;Han et al, 2012). Microelectrode measurements provide reliable and in situ information on the activity of microorganisms in biofilms formed on media (Chae et al, 2012).…”