[Relationship between phosphorus and bacterial regrowth in drinking water]

Area of Science:

• Environmental microbiology
• Water chemistry
• Public health

Context:

• Bacterial regrowth in drinking water distribution systems is a concern for water quality.
• Assimilable organic carbon (AOC) and microbially available phosphorus (MAP) are key nutrients influencing microbial proliferation.
• Understanding nutrient limitations is crucial for controlling bacterial populations in treated water.

Purpose:

• To investigate the role of phosphorus limitation in bacterial regrowth within a drinking water supply.
• To quantify MAP removal during water treatment and assess nutrient levels in source water and distribution systems.
• To differentiate the contributions of AOC and MAP to bacterial growth at various stages of the water supply.

Summary:

• Microbially available phosphorus (MAP) concentrations were higher in source water and during treatment (5-38 microg/L PO4(3-)-P) but decreased significantly in the distribution system (<5 microg/L PO4(3-)-P).
• Conventional water treatment effectively removed 34.0%-83.7% of MAP.
• While AOC was the primary driver of bacterial growth in source water and during treatment, phosphorus became the limiting nutrient in the distribution system, where AOC(potential) and AOC(P) were 2-8.7 times higher than AOC(native).

Impact:

• This study highlights the shift in limiting nutrients for bacterial growth from AOC to phosphorus as water moves through the distribution system.
• Findings suggest that managing phosphorus levels, in addition to AOC, is essential for controlling bacterial regrowth in drinking water.
• The research provides critical insights for optimizing water treatment and distribution strategies to ensure microbial water safety.