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Open AccessArticle

Density-Based Separation of Microbial Functional Groups in Activated Sludge

Department of Civil and Environmental Engineering, University of Nevada, Reno, NV 89557, USA
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Int. J. Environ. Res. Public Health 2020, 17(1), 376; https://doi.org/10.3390/ijerph17010376
Received: 15 November 2019 / Revised: 20 December 2019 / Accepted: 27 December 2019 / Published: 6 January 2020
(This article belongs to the Section Environmental Science and Engineering)
Mechanistic understanding of how activated sludge (AS) solids density influences wastewater treatment processing is limited. Because microbial groups often generate and store intracellular inclusions during certain metabolic processes, it is hypothesized that some microorganisms, like polyphosphate-accumulating organisms (PAOs), would have higher biomass densities. The present study developed a density-based separation approach and applied it to suspended growth AS in two full-scale domestic water resource recovery facilities (WRRFs). Incorporating quantitative real-time PCR (qPCR) and fluorescence in situ hybridization (FISH) analyses, the research demonstrated the effectiveness of density-based separation in enriching key microbial functional groups, including ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and PAOs, by up to 90-fold in target biomass fractions. It was observed that WRRF process functionalities have significant influence on density-based enrichment, such that maximum enrichments were achieved in the sludge fraction denser than 1.036 g/cm3 for the enhanced biological phosphorus removal (EBPR) facility and in the sludge fraction lighter than 1.030 g/cm3 for the non-EBPR facility. Our results provide important information on the relationship between biomass density and enrichment of microbial functional groups in AS, contributing to future designs of enhanced biological treatment processes for improved AS settleability and performance. View Full-Text
Keywords: activated sludge; density-based separation; enrichment of microbial functional groups; ammonia-oxidizing bacteria (AOB); nitrite-oxidizing bacterial (NOB); phosphate accumulating organisms (PAOs); qPCR; FISH activated sludge; density-based separation; enrichment of microbial functional groups; ammonia-oxidizing bacteria (AOB); nitrite-oxidizing bacterial (NOB); phosphate accumulating organisms (PAOs); qPCR; FISH
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Li, L.; You, Y.; Pagilla, K. Density-Based Separation of Microbial Functional Groups in Activated Sludge. Int. J. Environ. Res. Public Health 2020, 17, 376.

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