Seeding Advanced Treated Wastewater for Purposes of Direct Potable Reuse

Area of Science:

• Environmental Science
• Microbiology
• Water Treatment

Background:

• Water scarcity necessitates exploring direct potable reuse (DPR) by introducing advanced treated water (ATW) into distribution systems.
• Understanding the impact of ATW on existing microbial communities in water distribution systems is crucial for public health and system stability.

Purpose of the Study:

• To assess the effects of ATW on microbial water quality in simulated distribution systems.
• To investigate the role of biological filtration in seeding ATW and its persistence in distribution systems.

Main Methods:

• Simulated distribution systems were conditioned with surface water (SW) and then transitioned to ATW.
• Microbial water quality, including cell counts, ATP concentrations, and microbial community composition (16S amplicon sequencing), was measured.
• The impact of a biological filtration step on ATW was evaluated.

Main Results:

• ATW-fed systems showed lower bulk water cell counts and ATP, with a distinct microbial community compared to SW-fed or seeded ATW-fed systems.
• Biofilm community composition and biomass were consistent across all feedwater conditions.
• Seeded ATW exhibited increased microbial biomass and diversity, with specific microbial groups originating from the biological filter.

Conclusions:

• Directly introducing ATW into distribution systems may disrupt established microbial communities.
• Employing biological filtration for ATW preparation can lead to more predictable and stable microbial water quality in distribution systems.