High Ammonia Level in Yamuna

Context: The ongoing Yamuna water crisis has escalated into a political dispute between the Delhi & Haryana governments.

What is Ammonia?

• Ammonia (NH₃) is a colourless, water-soluble gas with a pungent smell.
• It is naturally present in the environment but can reach toxic levels due to human activities.

Major sources of ammonia pollution

• Runoff from agricultural lands (fertilizers and animal waste).
• Industrial discharge (dye units, distilleries, chemical plants).
• Untreated sewage from human settlements.
• Natural decomposition of organic matter like blue-green algae.

Health Impact of Ammonia

• Highly corrosive and can damage internal organs with prolonged exposure.
• Affects water quality, making it unsafe for human consumption.
• Long-term exposure can cause respiratory and digestive issues.

Why is Ammonia Pollution in the Yamuna a Concern for Delhi?

Sources of Ammonia in Yamuna (Haryana Region)

• Industrial discharge from dye units and distilleries in Panipat and Sonipat districts.
• Untreated sewage from residential colonies.
• Low water flow in winter worsens pollution as freshwater is scarce.

Impact on Delhi’s Water Supply

• Ammonia reduces the dissolved oxygen (DO) levels in water, making it unsuitable for consumption.
• Water Treatment Plants (WTPs) in Delhi cannot process water with ammonia levels above 1 ppm.
• When ammonia levels spike, Delhi faces water shortages due to treatment inefficiencies.
• The situation worsens in winter, as ammonia levels increase significantly due to reduced river flow.

Methods for Treating Ammonia-Laden Water

Chlorination (Chemical Treatment)

• How it works: Ammonia is neutralized using chlorine gas (Cl₂) or sodium hypochlorite (NaOCl).
• Limitation: Excess chlorine can lead to harmful disinfection byproducts (DBPs).

Biological Nitrification & Denitrification

• How it works: Bacteria convert ammonia into nitrites (NO₂⁻) and then nitrates (NO₃⁻), which are removed through further biological processes.
• Bacteria involved:
  • Nitrosomonas bacteria convert ammonia to nitrite.
  • Nitrobacter bacteria convert nitrite to nitrate.
• Limitation: Requires specific bacterial cultures and controlled conditions.

Reverse Osmosis (RO) & Ion Exchange (Membrane-Based Treatment)

• How it works: RO membranes filter ammonia molecules, removing them from water. This method is used in Singapore’s NEWater project for wastewater recycling.
• Limitation: Expensive and requires high energy input.

Constructing Wetlands (Nature-Based Solution)

• How it works: Wetland plants absorb ammonia from water. Microbial activity in root zones promotes natural nitrification.
• Limitation: Requires large areas and long-term monitoring.

Ammonia Stripping (Physical Process)

• How it works: Water is aerated at high pH (~10.5-11) to convert ammonium ions (NH₄⁺) into gaseous ammonia (NH₃), which escapes into the air.
• Limitation: Requires pH adjustment and high energy consumption.

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