Investigation on Lanthanum Modified Kaolinite for Control of Cyanobacterial Growth and Microcystin Production

Eutrophication and its resultant cyanobacterial blooms are a severe environmental issue in global water bodies, and phosphate is regarded as one of the primary triggers. In this study, the in situ-synthesized heated kaolinite lanthanum hydroxide composite (HKL-LH) was used to treat cyanobacterial blooms through phosphate removal. A typical cyanobacteria species—Microcystis aeruginosa—was selected as the target organism. HKL-LH efficiently removed phosphate in the solution with the inoculation of M. aeruginosa over the course of one day. A good performance of HKL-LH on control cyanobacterial blooms with initial cell densities ranging from 104 cells mL−1 to 105 cells mL−1 was observed. Although the genetic expression relating to photosynthesis and cell division was upregulated under the stress of phosphorus deficiency, M. aeruginosa growth was significantly inhibited, i.e., the inhibition rate of up to 98% was achieved by 0.1g L−1 of HKL-LH. In addition to cell growth, the photosynthetic activity and viability of M. aeruginosa cells were decreased by HKL-LH. Furthermore, the production of associated toxins (microcystins) and algal organic matters were effectively inhibited, which can reduce the ecological risk and challenges that follow water treatment. In this study, it is shown that HKL-LH has excellent application potential in the mitigation of cyanobacterial blooms in eutrophic water.