Investigation of the flocculating activity of oyster shell powders on Microcystis aeruginosa with varying particle size and mechanical conditions

Harmful algal blooms have been a serious environmental problem. The flocculation of Microcystis aeruginosa by oyster shell powders prepared by aerobic calcination (CO), anaerobic calcination (CN), acidification anaerobic calcination (CAN), and deacetylation anaerobic calcination (CHN) was studied. The CO800 (100 mesh) and CN800 (160 mesh) presented the highest flocculation rate of 89.46% and 77.39% when they were stirred for 1 min with speed of 750 r/min and 250 r/min, respectively. The photosynthesis and viability of the algae cells flocculated by CO800 with particle size of 100 mesh were not significantly damaged. The phosphorus nutrient could be removed by CO800 and CN800 effectively due to the presence of Ca 2+ , which also limited Microcystis aeruginosa growth. The study showed that the processing of oyster shell powder could be used as an effective flocculating material. Graphical Abstract