Density-Based Separation of Microbial Functional Groups in Activated Sludge

Abstract

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.

Spatial and temporal variability and data bias in wastewater surveillance of SARS-CoV-2 in a sewer system

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Removal of SARS‐CoV‐2 viral markers through a water reclamation facility

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Biological Activated Sludge from Wastewater Treatment Plant before and during the COVID-19 Pandemic

“…This condition is commonly associated with a sludge that is not the case of the studied wastewater treatment plant. The sludge flocs are usually light and fluffy because it has a low density [ 56 ]. Thus, the activated sludge from the studied WWTP is of good and healthy quality and the wastewater treatment process returns a high-quality effluent.…”