Factors affecting

Area of Science:

• Environmental Chemistry
• Water Treatment Chemistry
• Organic Chemistry

Background:

• Poly(diallyldimethylammonium chloride) (polyDADMAC) is a precursor to N-nitrosodimethylamine (NDMA), a probable human carcinogen.
• NDMA can form during water disinfection processes involving chloramine.

Purpose of the Study:

• To investigate the factors influencing NDMA formation from polyDADMAC during chloramination.
• To determine the optimal conditions for minimizing NDMA generation from polyDADMAC.

Main Methods:

• Orthogonal experimental design to assess the impact of pH, ammonia, bromide, natural organic matter (NOM), and monochloramine dosage.
• Single-factor experiments for pH, bromide, and NOM to validate orthogonal results.

Main Results:

• pH is the most critical factor, with peak NDMA formation near pH 7.
• Bromide significantly enhances NDMA formation via bromochloramine.
• Natural organic matter (NOM) reduces NDMA formation by 41.7%.

Conclusions:

• NDMA formation from polyDADMAC is controllable by managing water chemistry, particularly pH.
• Under simulated conditions, NDMA levels generally remained below advisory limits.
• Understanding these factors is crucial for safe drinking water treatment.