Microbiological impacts of blending advanced-treated wastewater in pipe loops

Direct potable reuse offers water-scarce regions a local and reliable source of drinking water through advanced treatment of wastewater, but few studies have investigated the microbial water quality impacts of introducing advanced-treated wastewater to drinking water distribution systems. The microbial water quality was characterized throughout an advanced wastewater treatment train and in pilot-scale simulated drinking water distribution systems. Drinking water distribution systems were simulated as pipe loops that recirculated 100 L of either conventional drinking water or blends of advanced-treated wastewater and conventional drinking water. Microbial water quality was assessed via 16S rRNA gene amplicon sequencing as well as flow cytometry-based cell counts, adenosine triphosphate concentration, and qPCR.