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NDMA formation in secondary wastewater effluent.
1Cranfield Water Science Institute, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK.
Chemosphere
|December 6, 2012
Summary
Concerns about N-nitrosodimethylamine (NDMA) in water reuse are rising. Chloramination, not chlorination, forms NDMA, with factors like temperature and contact time significantly impacting levels.
Area of Science:
- Environmental Chemistry
- Water Treatment Technologies
Background:
- N-nitrosodimethylamine (NDMA) is a disinfection byproduct of concern in water treatment.
- Chloramination, used in wastewater treatment, has been linked to increased NDMA formation, particularly in water reuse scenarios due to organic precursors.
Purpose of the Study:
- To investigate the formation of NDMA during chloramination of secondary wastewater.
- To identify key operational parameters influencing NDMA levels and determine strategies for mitigation.
Main Methods:
- Experiments were conducted on chloramination and chlorination of secondary wastewater under varying conditions.
- A full factorial analysis was performed to assess the impact of temperature, pH, monochloramine dose, and contact time on NDMA formation.
Main Results:
- Significant NDMA formation was observed exclusively with chloramination, not chlorination.
- Temperature, pH, monochloramine dose, and contact time all significantly influenced NDMA levels, with contact time being the most critical factor.
- At temperatures below 10 °C, NDMA can be controlled below 10 ng L(-1) with a monochloramine dose of 2 mg L(-1) or less.
Conclusions:
- NDMA formation during water treatment is highly dependent on chloramination conditions.
- Effective control of NDMA requires careful management of temperature, pH, monochloramine dose, and contact time, especially at higher water temperatures.
- Further research is needed to establish optimal operating parameters and explore pretreatment methods for NDMA precursor removal.
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