Back to WATER INSIGHTS
By Hanieh Salimian, Publishing Associate: Researcher and Writer at Save the Water™ | March 21, 2026
Edited by Apurva Makashir, Publishing Associate Vice President at Save the Water™
A traditional wastewater treatment process has three stages. The final stage removes the remaining contaminants through a different process. Duckweed systems can treat domestic wastewater using phytoremediation. Additionally, it is an efficient and cheaper alternative to tertiary treatment. Phytoremediation uses a plant’s ability to remove, purify, or stabilize contaminants.
Domestic wastewater is dangerous to both the environment and human health because of the high levels of the following:
Pathogens: Domestic wastewater can carry pathogens, such as E. coli, Schistosoma, and Pseudomonas species. This poses a major public health risk. Therefore, treatment processes must remove these pathogens to meet safety standards.
Excess Nutrients: Increased levels of nitrogen and phosphorus from treated wastewater entering water bodies can cause eutrophication. As a result, this harms wildlife and severely reduces water quality.
High Organic Load: Chemical Oxygen Demand (COD) determines high concentrations of harmful organic matter in wastewater. For example, when large amounts of algae die, they consume oxygen during decay. This reduces the oxygen levels in the water.
Chemicals: Dissolved salts, sulfates, and chlorides can be present at dangerously high levels to threaten aquatic life and damage infrastructure.
A combination of duckweed species Lemna gibba, Lemna minuta, and Wolffia columbiana can reduce contaminant levels enough for the treated water to meet regulatory standards.
Furthermore, the system can remove over 70% of phosphorus and COD during both summer and winter. However, in 30-day summer trials, phosphorus removal can reach up to 93%.
In addition, duckweed systems can remove 59% of nitrogen after 7 days in summer and 75% after 30 days. During summer, sulfate and chloride removal can exceed 50%. Additionally, duckweed produces a by-product called erucamide. This chemical removes pathogens by up to 99% under all conditions.
Duckweed’s Efficiency
Longer treatment times significantly improve water quality. After 30 days of treatment, compared with 7 days, microorganism removal increases, and the water becomes odorless and colorless.
Additionally, duckweed also maintains its effectiveness by adjusting its physiology. When exposed to wastewater, the plants increase chlorophyll pigment and protein content. This meets the higher energy demands required to remove contaminants.
Finally, scaling from laboratory to larger production with real-time conditions improves overall contaminant removal efficiency.
Phytoremediation offers a scalable, cost-effective, and sustainable solution for wastewater treatment in small communities. Furthermore, phytoremediation relies on the natural abilities of plants and their associated microbial communities. Therefore, systems require less infrastructure than traditional wastewater treatment plants. They also remain effective under different environmental conditions. Thus, this also indicates greater efficiency in larger volumes, highlighting their potential for large-scale wetland applications.
Save the Water™ is a 501 (c)(3) non-profit organization with a mission to conduct research to identify and remove harmful contaminants in water and to raise public awareness about water contamination and its health impacts.
