Impacts of Solids Retention Time and Antibiotic Loading in Activated Sludge Systems on Secondary Effluent Water Quality and Microbial Community Structure

Document Type

Article

Publication Date

1-28-2019

Publication Title

Water Environment Research

Volume

91

Issue

6

First page number:

546

Last page number:

560

Abstract

Solids retention time (SRT) is one of the most important factors in designing and operating activated sludge systems for biological wastewater treatment. Longer SRTs have been shown to alter the structure and function of microbial communities, thereby leading to improved treatment efficacy with respect to bulk and trace organics, nutrient removal, and membrane fouling. Research has also shown that longer SRTs and/or higher influent antibiotic concentrations may lead to increased prevalence of antibiotic resistance. However, it is unclear whether elevated, yet subclinical, concentrations of antibiotics also impact the overall microbial community. The purpose of this study was to characterize changes in microbial community structure in a laboratory‐scale activated sludge system as a function of SRT (2–20 days) and influent concentrations (1×–100× ambient) of ampicillin, sulfamethoxazole, tetracycline, trimethoprim, and vancomycin. Changes in microbial community structure were evaluated based on 16S rRNA gene sequencing, and microbial community function was evaluated based on changes in effluent water quality, including attenuation of bulk and trace organics. The results confirmed that longer SRTs—but not antibiotic loadings—had a significant impact on microbial community structure and effluent water quality. Therefore, moderate spikes in influent antibiotic concentrations are not expected to adversely impact biological wastewater treatment.

Keywords

16S rRNA gene; Activated sludge; Antibiotics; Microbial community; Solids retention time; Trace organic compound Wastewater treatment

Disciplines

Environmental Engineering | Hydrology

Language

English

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