Modified mussel shell powder for microalgae immobilization to remove N and P from eutrophic wastewater

In this work, calcined mussel shell powder (CMSP) was activated by K₂CO₃ (K-CMSP), and this porous K-CMSP surface was modified by L-arginine (L-ARG) to render porous biomass a positively charged surface, which was innovatively utilized as a carrier to immobilize microalgae by adsorption via electrostatic interactions. The pore and the surface structures of CMSP and K-CMSP were characterized by XRD, FTIR, BET and SEM. The surface morphology of immobilized microalgae was visualized via using inverted optical microscope and SEM. It was found that microalgae could survive for 60 days, and the loss rate of chlorophyll-a preserved at -24 °C was the lowest, 44.73%. The microalgae could revive to normal growth level within 10 days and the cell content of microalgae was the highest at 25 °C, 2.8022 × 10⁶ cell/mL. At 25 °C, the highest removal rate of N and P was obtained about 95.0% and 88.63%, respectively.