Sewage Parameters 5: Ammonia (NH4)
Hi,
The last topic that was discussed on this blog was Phosphorus (P). Next we are going to move on to the complex topic of Ammonia (NH4) and how to remove it from sewage. The presence of nutrients in wastewater, such as nitrogen (N) has long been recognised as a source of over enrichment of receiving environments. This over enrichment can lead to explosive plant growth and algae blooms, resulting in eutrophication, fish kills etc. Therefore, the removal of these nutrients has become an everyday requirement in the treatment of sewage and other waste waters.
The aerobic removal of ammonia is a process called nitrification. This converts the ammonia (NH4) into Nitrate (NO3). As the nitrifying bacteria are generally more sensitive than the carbonaceous bacteria, the nitrification process should be designed as a separate stage or aerobic treatment, after the main BOD removal process.
In regards to a package sewage treatment plant such as the BMS Blivet this means that nitrification should be designed as an additional Blivet or Aerotor stage, operating in series with the first BOD Blivet removal stage. Average NH4 concentrations in domestic sewage influent are about 40 mg/L. However, there is a large caveat on this figure. Where water usage is less than average, concentrations can shoot up. For example, previous experience in French villages has shown inlet ammonia concentrations up to 100 mg/L! Due to the more fragile nature of the microbes that effect nitrification, most nitrification occurs after the BOD removal or carbonaceous stages. Therefore, we must design an additional aerobic section proportional to the amount of ammonia we wish to remove. Ammonia normally requires 3 to 4 times the aerobic capacity required for BOD removal. Nitrification is also notoriously temperature sensitive. For this reason we use the ratio of 4 times BOD capacity for cold and temperate climates, and 3 times BOD capacity for warm and hot climates. In cold winter climates a combination of insulation and heating may be required to ensure the temperature of the liquor never falls below 8ºC.
Next up for discussion is some examples of calculations to work out the additional treatment capacity required for Nitrification (Ammonia NH3 removal).
If you have any specific queries or there is any topics you would like explored, please do not hesitate to contact us.
A bit about the company:
BMS is a quality manufacturer of package products for wastewater and stormwater treatment. BMS started in 1986 and has exported products to over 50 countries around the world. It is a third generation family business with huge expertise in wastewater and stormwater.
BMS manufacture a full range of products for surface water and wastewater treatment including our pioneering next generation RBC system the Aerotor, which forms part of our world leading Blivet package sewage treatment plant, a ‘one stop shop’ for all surface water products from design to installation including attenuation, interceptors, holding tanks (incl. chemical resistant), hydrobrakes, rainwater harvesting tanks & vortex silt/oil/debris separators, fully fitted pumping stations, our plug & play vehicle wash water recycling system; the Recyclone and much more. All BMS products manufactured in our ISO 9001 factory are made using solar energy from our own PV system.
BMS also can provide a Free Design Service for Sewage Treatment, Pump Stations or Surface Water and a full O&M, Repair, Advice and Testing service for existing installations. We also can do free CPD Presentations on Sewage Treatment/Surface Water Management at any location.
We would be delighted to discuss any requirements you might have and we are available to meet you at your convenience. Please do not hesitate to contact us.
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