Efficient inhibition of Microcystis aeruginosa using expanded perlite sustained-release pyrogallic acid: performance...

Allelochemicals are effective and safe for controlling cyanobacterial blooms, but their direct application suffers from rapid degradation and poor persistence. To address this limitation, we engineered a buoyant, surface-targeting delivery system to inhibit non-toxic and toxic Microcystis aeruginosa by preparing PA/Expanded perlite composites using expanded perlite as a matrix. The results showed that PA was successfully loaded onto expanded perlite, and PA/Expanded perlite could achieve long-term release of phenolic release (PA-dominant). PA/Expanded perlite was effective in removing both non-toxic and toxic M. aeruginosa, with the maximum inhibition rate of 97.60 %, and the EC₅₀ (7d) values were 15.60 and 6.90 mg/L, respectively. The PA/Expanded perlite composite achieved a 97.62 % inhibition rate against M. aeruginosa in natural landscape water. Additionally, treatment with PA/Expanded perlite significantly reduced chlorophyll a and phycobiliprotein content in both algal strains, and the photosynthetic rates of toxic and non-toxic M. aeruginosa decreased to 0.03 and 0.0043 [μmol/(mg·h)], respectively. Meanwhile, the activities of superoxide dismutase (SOD) and catalase (CAT) and the content of malondialdehyde (MDA) were significantly increased. Under current exposure levels, PA/Expanded perlite did not pose harm to Daphnia magna and Pteris vittata, while significantly reducing intracellular microcystin-LR (MC-LR) contents, which has promising application for the control of water blooms.