Impact of conventional wastewater treatment and reuse site practices on the bacterial community structure of reclaimed water

Published: October 15, 2018

Author(s)

Prachi Kulkarni, Nathanael D. Olson, Joseph N. Paulson, Mihai Pop, Cynthia Maddox, Emma Claye, Rachel E. Rosenberg Goldstein, Manan Sharma, Amy R. Sapkota

Abstract

Reclaimed water use continues to expand across the United States, from areas that have access to advanced, potable-level treated reclaimed water, to areas that only have access to reclaimed water treated at conventional municipal wastewater treatment plants. This expansion makes it even more important to further characterize the microbial quality of these conventionally-treated water sources. Therefore, we used 16S rRNA gene sequencing to characterize total bacterial communities present in differentially treated wastewater and reclaimed water (n=67 samples) from four U.S. wastewater treatment plants and one associated spray irrigation site conducting on-site ultraviolet treatment and open-air storage. The number of observed operational taxonomic units was significantly lower (p<0.01) in effluent, compared to influent, after conventional treatment. However, the relative abundance of Legionella increased as treatment progressed in one treatment plant that performed chlorination and in one plant that did not chlorinate. Overall, the alpha-diversity of bacterial communities in reclaimed water decreased (p<0.01) during wastewater treatment and spray irrigation site ultraviolet treatment (p<0.01), but increased (p<0.01) after open-air storage at the spray irrigation site. Ultraviolet treatment at the spray irrigation site had no effect on Legionella and Mycobacterium relative abundance. The relative abundance of Legionella was higher at the sprinkler system pumphouse at the spray irrigation site than in the influent from the treatment plant supplying the site. These data suggest that conventional wastewater treatment and reuse site practices may not effectively reduce the occurrence of some opportunistic pathogens in reclaimed water, and additional treatment approaches are necessary to protect public health.
Citation: Science of the Total Environment
Volume: 639
Pub Type: Journals

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Keywords

Wastewater treatment, bacteria, 16S rRNA gene sequencing, reclaimed water, public health, water reuse
Created October 15, 2018, Updated November 10, 2018