Importance of Nitrogen Control in Wastewater Treatment

Nitrogen Removal Methods

In wastewater, nitrogen is primarily present in these forms: ammonium (NH4-N), ammonia (NH₃), nitrite (NO₂⁻), and nitrate (NO₃⁻), each of which requires a distinct approach for effective treatment.

Conventional Activated Sludge (CAS)

Conventional Activated Sludge (CAS) is one of the most widely used methods for nitrogen removal. In this process, wastewater is aerated in tanks, promoting the growth of microorganisms that break down nitrogen compounds. Nitrifying bacteria oxidize ammonia to nitrite and then to nitrate. While effective at removing ammonia, nitrate must be further treated, usually through denitrification, to fully remove nitrogen. CAS is energy-intensive due to constant aeration and pumping.

Nitrification-Denitrification

Nitrification-denitrification is a two-step biological process that is highly effective for reducing nitrogen in wastewater. First, nitrifying bacteria oxidize ammonia to nitrate in an oxygen-rich environment. Then, denitrifying bacteria convert nitrate to nitrogen gas (N₂) in an anaerobic environment, using an external carbon source. This process is highly effective for nitrogen removal but requires careful control of oxygen levels and sufficient carbon for denitrification.

Nitrogen Control Challenges

Controlling nitrogen in wastewater treatment is difficult, with facilities facing numerous challenges like: 

• Microorganism Sensitivity
  The microorganisms that drive nitrogen removal in processes, like nitrification and denitrification, are sensitive to their surroundings. These microorganisms can be adversely affected by changes in environmental conditions, such as pH, temperature, or exposure to toxic substances, which can reduce their effectiveness.
• External Carbon Source
  Another major challenge is the requirement for an external carbon source to support denitrification. This adds both complexity and cost to the treatment process. Incomplete processing can lead to the accumulation of nitrates, necessitating further treatment stages. Additionally, nitrification processes are highly energy-intensive, which significantly increases operational costs.
• Wastewater Variability
  The composition of wastewater can vary widely, further complicating nitrogen removal efforts. Differences in the levels of ammonium or the carbon-to-nitrogen ratio can make it difficult to maintain optimal treatment conditions. This variability is particularly problematic in large-scale facilities, where maintaining stable, consistent operations remains a significant challenge.

Innovative Nitrogen Control Solutions

BlueEdge™ by Badger Meter meets these challenges head-on by providing technologies that offer critical insights into nitrogen pollution levels and overall water quality in wastewater treatment processes. These tools track the nitrification-denitrification process, empowering treatment facilities with real-time data for faster, more proactive maintenance and immediate response to emerging issues. This level of insight not only helps to protect aquatic environments, but also ensures safe drinking water supplies and promotes public health.

A great example of its impact is at the Jianshan Wastewater Treatment Plant in China. To meet the "12th Five-Year Plan" discharge standards, the plant implemented a nitrogen removal process using BlueEdge online monitoring tools, including the nitro::lyser V3 and ammo::lyser Pro, which were installed in four SBR tanks. This upgrade allowed for precise control of nitrification and denitrification, leading to reduced aeration and carbon source costs. As a result, the plant reduced COD and NH4-N emissions by 50%, significantly lowering Total Nitrogen levels in the effluent and improving the water quality of the Qiantang River.

Conclusion

Managing nitrogen levels in wastewater is essential for protecting ecosystems and public health. BlueEdge™ provides real-time insights and proactive solutions to address challenges like microorganism sensitivity and wastewater variability. Success stories from various facilities highlight the effectiveness of these technologies in enhancing water quality and operational efficiency, contributing to a healthier environment.