Nitrogen Removal and Recovery from Wastewater.

Author: Ahmed Bakhiet – Project Manager – Coftec

Nitrogen removal and recovery from wastewater is a crucial issue for sustainable development and environmental protection. In this blog post, we will explore the importance, benefits, and methods of nitrogen management in wastewater and how Coftec can help you achieve it with innovative solutions.

Nitrogen is an essential element for life, but too much of it can cause serious problems for the environment. When nitrogen enters water bodies through various sources, such as agricultural runoff, wastewater discharge, urban runoff, and industrial activities, it can trigger a series of negative effects that threaten the health and balance of aquatic ecosystems. Some of the environmental risks of nitrogen pollution are:

• Harmful Algal Blooms: Elevated nitrogen levels can fuel the growth of harmful algae, which are microscopic organisms that can produce toxins that harm aquatic life and human health. Harmful algal blooms can also reduce the clarity and aesthetics of water, affecting recreational activities and tourism.
• Deoxygenation: Decomposition of excess algae consumes oxygen, leading to hypoxic or anoxic conditions that suffocate aquatic life. Hypoxia is a condition where dissolved oxygen levels are below 2 mg/L, while anoxia is a condition where dissolved oxygen levels are zero. Hypoxic and anoxic zones can create dead zones, which are areas where aquatic life cannot survive.
• Damage to aquatic ecosystems: Nitrogen pollution can disrupt the balance of aquatic ecosystems, leading to biodiversity loss and compromised water quality. Nitrogen pollution can alter the composition and function of aquatic communities, favoring some species over others and reducing the resilience and diversity of ecosystems. Nitrogen pollution can also affect the cycling of other nutrients, such as phosphorus and carbon, and influence the acidification and greenhouse gas emissions of water bodies.

Therefore, it is important to implement effective strategies for nitrogen removal and recovery from wastewater to prevent the degradation of water bodies and to utilise nitrogen as a valuable resource for agricultural and industrial applications.

What are the Benefits of Nitrogen Removal and Recovery from Wastewater?

Nitrogen removal and recovery from wastewater is not only important for environmental protection, but also for social and economic development. By implementing effective strategies for nitrogen management in wastewater, we can achieve multiple benefits, such as:

• Improving water quality: By removing excess nitrogen from wastewater, we can prevent eutrophication, algal blooms, hypoxia, and toxicity in water bodies. This can improve the quality of drinking water, recreational water, and irrigation water. It can also protect aquatic ecosystems and biodiversity from degradation and disruption.
• Reducing greenhouse gas emissions: By recovering nitrogen from wastewater, we can reduce our dependence on synthetic fertilizers, which are energy-intensive and contribute to greenhouse gas emissions. According to a study by Liu et al., nitrogen recovery from wastewater can reduce greenhouse gas emissions by 6.6% compared to conventional wastewater treatment.
• Saving costs and generating revenue: By recovering nitrogen from wastewater, we can save costs on fertilizer production and purchase. We can also generate revenue by producing high-quality products from nitrogen-rich waste streams, such as fertilisers, animal feed, bioplastics, etc. For example, a project by Ostara in Canada recovered more than 700 tons of phosphorus and nitrogen from wastewater per year and produced a fertiliser product called Crystal Green.
• Enhancing food security and circular economy: By recovering nitrogen from wastewater, we can enhance food security by increasing crop yields and reducing fertiliser imports. We can also promote circular economy by closing the loop of nutrient cycles and minimising waste generation.

Therefore, it is clear that nitrogen removal and recovery from wastewater is a win-win solution for all stakeholders. By adopting innovative technologies and methods for nitrogen management in wastewater, we can create a more sustainable and resilient future for ourselves and our planet.

What are the Methods of Nitrogen Removal and Recovery from Wastewater?

To combat nitrogen pollution, researchers and engineers are pioneering innovative technologies for nitrogen removal and recovery from wastewater. These technologies hold the potential to transform wastewater treatment, reduce environmental impact, and foster resource efficiency.

Enhanced Biological Nitrogen Removal (EBNR)

Similar to Enhanced Biological Phosphorus Removal (EBPR) which was covered in the previous blog post, Enhanced Biological Nitrogen Removal (EBNR) is a biological process that harnesses specific bacteria to remove nitrogen from wastewater. Through distinct anaerobic and aerobic phases, these bacteria facilitate the conversion of nitrogen compounds into harmless nitrogen gas. EBNR not only reduces nitrogen pollution but also offers a sustainable approach to nitrogen removal, as it produces no phosphorus-rich sludge and enables nitrogen recovery for beneficial use.

Here are some of the benefits of EBNR:

• Efficient Nutrient Removal: EBNR excels at reducing nitrogen levels in wastewater to remarkably low concentrations, often reaching levels below 1 mg/L.
• Sustainability at its Core: Unlike other methods, EBNR generates little to no phosphorus-rich sludge.
• Adaptive and Versatile: EBNR seamlessly integrates with various wastewater treatment setups, be it traditional activated sludge systems or cutting-edge membrane bioreactors.

In summary, EBNR emerges as an impressively effective and eco-friendly approach for curbing nutrient presence in wastewater. Though more intricate compared to simpler solutions, the investment pays off through substantial environmental gains.

Membrane Filtration and Adsorption

Advanced membrane filtration technologies, such as reverse osmosis and nanofiltration, can selectively remove nitrogen compounds from wastewater. The membranes act as barriers, allowing only certain-sized molecules to pass through, effectively producing high-quality, clarified water.

While it may not directly target nitrogen compounds, membrane filtration indirectly contributes to nitrogen removal by removing suspended solids, bacteria, and organic matter. These contaminants often contain nitrogen in various forms, including ammonia and organic nitrogen compounds.

Adsorption is another treatment approach used to remove nitrogen compounds from wastewater. By leveraging adsorbent materials, this process effectively captures nitrogen-containing molecules on the surface of solid particles.

One common application of adsorption for nitrogen removal is using activated carbon. Activated carbon has a porous structure that provides a large surface area for adsorption. In the case of nitrogen removal, activated carbon can adsorb organic nitrogen compounds, ammonia, and nitrate ions from wastewater. The adsorption process relies on the attraction between the nitrogen compounds and the surface of the activated carbon.

Additionally, specialized ion exchange resins can be used to target specific nitrogen compounds. These resins can selectively adsorb ions like ammonium (NH4+) or nitrate (NO3-), effectively reducing their concentrations in the treated water.

Here are some of the benefits of membrane filtration and adsorption:

• High-Quality Water Production: Membrane filtration and adsorption can produce water that meets stringent quality standards for drinking or reuse purposes.
• Modular and Scalable: Membrane filtration and adsorption systems can be easily installed and operated in various scales and locations.
• Recovery Potential: Membrane filtration and adsorption systems can recover valuable products from wastewater streams, such as fertilisers, biogas, chemicals, etc.

In summary, membrane filtration and adsorption are advanced technologies that can effectively remove nitrogen compounds from wastewater. They also offer opportunities for water reuse and resource recovery.

Conclusion

In this blog post, we have explored the importance of nitrogen removal and recovery from wastewater for sustainable development and environmental protection. We have discussed the sources and impacts of nitrogen pollution, the benefits of nitrogen recovery, and the methods and technologies for nitrogen management in wastewater. We have also highlighted the potential of nitrogen recovery as a resource for agricultural and industrial applications, contributing to food security, circular economy, and resource efficiency.

However, achieving effective nitrogen removal and recovery from wastewater requires a deep understanding of advanced treatment methods and comprehensive solution integration. That is why you need a reliable partner who can offer you cutting-edge technologies and customised solutions for your specific wastewater needs.

At Coftec, we stand at the forefront of innovation in the circular economy, committed to harnessing the potential of nutrient recovery technologies. As a leading provider of water and wastewater solutions in Ireland, we offer a range of solutions for efficient nitrogen management in wastewater, such as those mentioned in this blog.

Our team of experts can help you evaluate your specific wastewater composition, identify optimal recovery processes, and design tailored treatment systems to extract maximum value from your nitrogen stream. We also provide ongoing operational support to ensure consistent system performance and nitrogen recovery.

If you are interested in learning more about our sustainable nutrient recovery solutions, get in touch with our water treatment specialists today. We are dedicated to empowering businesses to lead the way towards a circular economy. With the right partnership, you can efficiently convert wastewater into a renewable nitrogen source, aligning your practices with ecological responsibility and cost-effectiveness.

Don’t miss this opportunity to transform your wastewater into a valuable resource.

Contact us today and discover how we can help you achieve your nitrogen removal and recovery goals.

References

Liu, Y., Li, Z., Li, X., Wang, H., Zhang, J. and Wang, X., 2017. Greenhouse gas emission reduction and energy recovery from waste management. Waste Management, 67, pp.131-137.

Wastewater Digest (2008) Ostara to Build Nutrient Recovery Facility in Canada. Available at: https://www.wwdmag.com/home/news/10920261/ostara-to-build-nutrient-recovery-facility-in-canada, (Accessed: 4 September 2023).