New study shows how modified clay can fight red tide organisms

Red tides can wreak havoc on marine ecosystems and are becoming a global problem. Currently, the primary remediation technology used for large-scale red tide control is spraying modified clay (MC) onto the surface of water affected by red tides.

However, MC dosage is usually judged by previous spraying experience – but that doesn’t guide application very well.

Recently, a research team led by Professor Yu Zhiming from the Institute of Oceanology, Chinese Academy of Sciences (IOCAS) revealed how the dosage of MC affects its effectiveness in fighting red tides. The research team also created a mathematical model that describes the effectiveness of MC doses in controlling red tide organisms. The study was published in Separation and purification technology October 22.

Researchers found that when using MC to flocculate red tide organisms, its ability to remove microalgae initially increased, but decreased as modified clay was added. The total interaction energy between the clay and the short-range red tide organisms caused the clay to self-flocculate, decreasing its ability to remove harmful microalgae. The researchers also learned that the dosage of modified clay impacts the proportion of self-flocculation by interfering with the collision between the clay and the microalgae cells – this collision is what makes the clay effective in stopping red tide organisms.

According to the researchers, their mathematical model makes it possible to simulate different dosages of modified clay and to indicate which would be the most effective. The model can also illustrate the quantitative relationship between the dosage of MC and its degree of auto-flocculation.

“The spraying method of MC strongly affects its efficacy, and the dosage-efficacy mathematical model can be used as an important reference for the strategy of optimizing the dosage of MC,” said Zang Xiaomiao, first author of the study. .

“The study will help enrich the theory of particle flocculation and guide effective spraying practices of MC technology for red tide control,” said Professor Yu, the corresponding author of the study.