Sewage Parameters 5 Part 2: Ammonia (NH4)

Introduction

Continuing our exploration of sewage parameters, today’s topic is Ammonia (NH₄) and its removal from wastewater. Ammonia, a form of nitrogen, is a significant nutrient in wastewater and a major contributor to environmental issues such as eutrophication, algae blooms, and fish kills when released untreated into watercourses.

Why Remove Ammonia?

The presence of nutrients like nitrogen in wastewater leads to over-enrichment of receiving environments, which can cause:

• Explosive plant growth and algae blooms.

• Deoxygenation of water.

• Fish kills and other ecological damage.

For this reason, ammonia removal is now a routine requirement in sewage treatment.

The Process: Nitrification

Nitrification is the aerobic biological process that converts Ammonia (NH₄) into Nitrate (NO₃).

1. Two-Stage Process:

   • Stage 1: Ammonia (NH₄) → Nitrite (NO₂)

   • Stage 2: Nitrite (NO₂) → Nitrate (NO₃)

2. Nitrifying Bacteria:

   • More sensitive to environmental conditions than carbonaceous bacteria.

3. Separate Treatment Stage:

   • Due to their sensitivity, nitrification is typically designed as a separate aerobic stage after the main BOD removal process.

Application in Package Sewage Treatment

For a BMS Blivet, nitrification involves:

• Additional Aerobic Stage:

  • An additional Blivet or Aerotor unit is installed in series with the initial BOD removal stage.

• Ammonia Concentrations:

  • Domestic sewage influent typically contains ~40 mg/l of NH₄.

  • However, concentrations can vary:

    • Lower water usage areas may see concentrations up to 100 mg/l (e.g., in French villages).

Design Considerations

1. Aerobic Capacity:

   • Ammonia removal requires 3–4 times the aerobic capacity needed for BOD removal.

     • Cold and Temperate Climates: Use a factor of 4.

     • Warm and Hot Climates: Use a factor of 3.

   • In cold climates, additional insulation and heating may be required to maintain liquor temperatures above 8°C.

2. Temperature Sensitivity:

   • Nitrification efficiency drops significantly at low temperatures.

3. Proportional Design:

   • The size of the additional aerobic stage must be proportional to the amount of ammonia requiring removal.

What’s Next?

In the next installment, we’ll provide examples of calculations to determine the additional treatment capacity needed for Nitrification (Ammonia NH₃ removal).

Questions?

If you have any queries or specific topics you’d like us to explore, feel free to reach out. We’re here to help!

About BMS

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• Established: 1986

• Global Reach: Exported to over 50 countries.

• Family Business: A third-generation company with deep expertise.

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BMS provides a wide array of surface water and wastewater treatment products, including:

• Attenuation systems

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