Reverse Osmosis in an Advanced Water Treatment Train Produces a Simple, Consistent Microbial Community

Area of Science:

• Environmental microbiology
• Water treatment technologies

Background:

• Potable water reuse is crucial for water sustainability, especially in arid regions.
• Reverse osmosis (RO) is a key technology in water purification, but microbial regrowth in RO permeate is a challenge.
• Low biomass in RO permeate limits traditional microbiological analysis.

Purpose of the Study:

• To identify microorganisms in RO permeate and their source.
• To understand the microbial community dynamics in a potable water reuse facility.
• To investigate the survival and metabolic potential of bacteria in RO permeate.

Main Methods:

• High-throughput sequencing of microbial communities in water samples and RO membrane biomass.
• Analysis of samples from various stages of a potable reuse treatment train.
• Metagenome-assembled genome reconstruction for key microbial species.

Main Results:

• A stable and consistent microbial community was observed in RO permeate over three months.
• Burkholderiaceae, particularly an Aquabacterium sp., dominated the RO permeate microbial community.
• The identified Aquabacterium sp. genome suggests utilization of low molecular weight organic molecules and likely originates from biofilms.

Conclusions:

• Biofilm formation on infrastructure, not treatment breakthrough, is the probable source of microorganisms in RO permeate.
• Aquabacterium sp. possesses metabolic pathways enabling survival and growth on residual organic molecules in purified water.
• Understanding these microbial dynamics is essential for optimizing potable water reuse systems.