Ammonia in drinking water can have implications for health, water treatment, and environmental quality. Ammonia occurs in the form of ammonium ions(NH₄⁺) in water with a neutral pH.
The sources of ammonia in drinking water are
- Natural processes, such as the breakdown of organic matter.
- Agricultural runoff (fertilizers).
- Industrial discharges.
- Chloramination, a water disinfection process, can result in ammonia in treated water.
Ammonia is not highly toxic to humans at typical levels found in drinking water but can pose indirect risks:
1. Direct Health Effects:
- Ammonia itself is generally not harmful in low concentrations.
- At very high concentrations, it may irritate the gastrointestinal tract or mucous membranes.
2.Indirect Health Risks:
- Ammonia can react with chlorine during water treatment to form chloramines, which may alter the taste and smell of water.
- Excessive chloramine formation can reduce the effectiveness of disinfection, increasing the risk of microbial contamination.
- It can promote the growth of nitrifying bacteria in distribution systems, leading to the production of nitrates and nitrites. High levels of these compounds can cause methemoglobinemia (blue baby syndrome) in infants.
Ammonia Removal from Drinking Water
Ammonia can be removed or reduced using various water treatment methods:
1. Biological Filtration:
- Utilizes nitrifying bacteria to convert ammonia into nitrate (nitrification).
- Effective for water systems with biological treatment facilities.
2. Ion Exchange:
- Ammonia ions are exchanged with other ions, such as sodium, in resin columns.
- Suitable for small-scale or household applications.
3. Chemical Oxidation:
- Chlorination: Converts ammonia to nitrogen gas or chloramines, but may require subsequent steps to remove chloramines.
- Ozonation: Oxidizes ammonia to nitrogen gas or other harmless compounds.
4. Reverse Osmosis (RO):
- Removes ammonia and other contaminants by forcing water through a semi-permeable membrane.
- Highly effective but costly.
5. Distillation:
- Boiling water to remove ammonia and other impurities.
- Effective but energy-intensive.
6. Break-point Chlorination:
- Adding chlorine to oxidize ammonia completely into nitrogen gas.
- Requires precise dosing to avoid residual chloramine formation.
Regulatory Standards
- There are no specific limits for ammonia in drinking water set by the World Health Organization (WHO), as it is generally not toxic at low concentrations.
- However, levels higher than 0.2 mg/L may affect water quality, taste, and odor.
For optimal health and water quality, regular monitoring and appropriate treatment strategies are recommended for water systems with detectable ammonia levels.
