Xia Ting,Wang Shi-qi,Yan Hang,Gao Zai-zhuang,Qiu Yao,Yuan Fang,Huang Guang-yong,Zhou Jun
Montmorillonite modified lime-ceramic sand-lake sediment (LC-sediments) was synthesized and its algae removal efficiency was investigated in this study. Montmorillonite not only improved the morphology and surface area of original LC-sediments, but also promoted the algal removal rate due to its inherent properties such as accumulating an electric charge, acting as a flocculant, and displaying a local bridging effect. Based on parameter optimization including the ratio of raw materials, agent dosage, initial algae density, pH and a determination of overlying water, the effect of hydrodynamic conditions on the algal removal process was researched. Under the optimal condition, the removal rates of turbidity, algae density and chlorophyll a could reach 86, 88 and 68%, respectively. As verified with a response surface model, it was shown that low disturbance (stirring) of the algae could promote algal removal by montmorillonite modified LC-sediment. Furthermore, a water column was utilized to approximatively simulate the flocculation and algae control in shallow lakes. This study solved the problem of reducing the dosage of lake sediment and improving the removal efficiency of algae without causing secondary pollution to the environment. It was expected to provide a certain theoretical basis for clay flocculation-based algae control in a real environment. Hydrodynamic conditions on algal removal process were studied. Montmorillonite improved algal control efficiency of modified lake sediment. Water column was utilized to simulate the state of natural lakes. The removal rates of turbidity and algae reached 86 and 88%, respectively.
Utilizing the allelopathic effect of plants to inhibit algae growth has gained significant attention from researchers in recent years. However, there are large amounts of microplastics in the aquatic environment, which may influence the inhibitory effects of allelochemicals on algae. Consequently, this research aimed to examine the individual and combined toxicity of gallic acid (GA) and polyethylene glycol terephthalate (PET) microplastics on Microcystis aeruginosa. At a concentration of 50 mg/L, PET significantly enhanced algal cell growth and chlorophyll a synthesis, while inducing oxidative stress without damaging the cell membrane. On the other hand, low concentrations of GA promote algal cell growth. However, high concentrations of GA not only inhibit growth and photosynthesis but also result in cellular abnormalities and severe oxidative damage, as well as membrane disruption. Moreover, it was observed that the exposure of PET diminished the toxicity of GA to M. aeruginosa . The combined exposure to GA and PET resulted in a slight increase in chlorophyll a content, as well as phycocyanin (PC), alloxyphycocyanin (APC), and phycoerythrin (PE) content, along with maximum photochemical efficiency (Fv/Fm), compared to GA exposure alone. In the combined system of GA and PET, the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) were lower than those in the single GA system. Additionally, both systems showed a degree of improvement compared to the control group. Scanning electron microscopy (SEM) observed that the presence of PET resulted in reduced damage to algal cells compared to exposure to GA alone. This research establishes a foundation for understanding the synergistic impacts of allelochemicals and microplastics on M. aeruginosa , thereby providing a reference for managing cyanobacteria in water blooms.
危险品化学品经营许可证（带存储）