Duckweed: A natural solution for water purification
Water pollution is a growing concern worldwide, with wastewater treatment becoming an essential aspect of environmental protection. While conventional treatment systems are effective, they can be costly and resource-intensive. Fortunately, nature provides a simple and sustainable alternative: duckweed. This small, fast-growing aquatic plant has shown remarkable potential in purifying wastewater by removing harmful nutrients and pollutants. Recent research highlights how duckweed can play a crucial role in improving water quality while offering additional environmental benefits.
How duckweed cleans wastewater
Duckweed, and particularly the common species Lemna minor or lesser duckweed, is highly efficient in absorbing pollutants from water. Studies have shown that when introduced into wastewater treatment systems, duckweed significantly reduces contaminants such as nitrogen, phosphorus, and suspended solids. These pollutants, if left untreated, can lead to complex issues such as eutrophication, where excess nutrients promote excessive algae growth, depleting oxygen levels in water bodies and harming aquatic life.
A study elaborated by Ahmadi and Dursun (2023) demonstrated that duckweed in secondary clarifier tanks of a wastewater treatment plant could remove up to 84% of chemical oxygen demand (COD), 87% of total nitrogen (TN), and 85% of total phosphorus (TP). These figures highlight how duckweed has the potential to enhance conventional biological treatment methods, through natural filtration by naturally filtering and breaking down organic matter [1].
Cost-effective and environmentally friendly
Traditional wastewater treatment systems often rely solely on chemicals and extensive infrastructure, which makes them expensive to implement, especially in densely populated urban areas. Research conducted by Krishnanunni and Anitha (2023) found that duckweed and Azolla (another aquatic plant) provide a more affordable and environmentally friendly alternative. These plants thrive in shallow ponds, requiring minimal land and maintenance, making them suitable for municipal wastewater treatment [2].
Additionally, the study revealed that duckweed and Azolla effectively remove pollutants while producing valuable biomass that can be used as fertilizer or animal feed. This dual benefit makes duckweed-based treatment systems a sustainable option for communities looking to reduce costs and environmental impact. Moreover, the biomass harvested from duckweed can be repurposed as animal feed, fertilizer, or biofuels. This, in turn, closes the loop and supports a circular, zero-waste approach to water management.
Large-scale application and practical considerations
The success of duckweed in full-scale wastewater treatment systems has been demonstrated in places like the Inverell Sewage Treatment Works in Australia. A report by the Urban Water Research Association of Australia (1999) showed that duckweed significantly reduced ammonia levels by 30% and phosphorus levels by up to 36%. This was achieved while suppressing algae growth. These findings confirm that duckweed is not limited to a theoretical solution, yet it can be deployed as a practical and effective method for improving wastewater treatment efficiency [3].
However, there are key considerations to ensure optimal performance. Namely, duckweed thrives best in temperatures around 26°C (Ahmadi and Dursun, 2024) and requires moderate nutrient levels to grow effectively. The study also highlighted the importance of managing sludge and ensuring proper harvesting techniques to maintain efficiency. In some cases, adding a small amount of nitrogen to the system can improve duckweed growth, further enhancing its ability to remove pollutants.
Conclusion
Duckweed presents a natural, cost-effective, and efficient way to purify wastewater. By absorbing pollutants, suppressing algae, and producing useful biomass, this tiny plant offers a sustainable alternative to traditional wastewater treatment methods. With growing global water challenges, integrating duckweed into wastewater management systems could help protect our water resources while reducing costs and mitigating environmental impacts. Future research and wider adoption of duckweed-based treatment systems have the potential to transform the way we manage wastewater, making cleaner water more accessible to communities around the world.
References
[1] Ahmadi, A.W., & Dursun, S. (2024). Assessing the efficiency and role of duckweed (Lemna Minor) in the removal of pollutants from wastewater treatment plant secondary clarifier tanks: A comprehensive review.
[2] Krishnanunni, U., & Anitha, K. (2023). Evaluation of potential of Azolla and duckweed in municipal wastewater treatment.
[3] Urban Water Research Association of Australia. (1999). Application of Duckweed in Treating Municipal Wastewater. Trials at Inverell STW.
The article was written by reframe.food.
All photographs in this article are sourced from Freepik and Envato.
