Methylated mud snail protein as a bio-flocculant for high turbidity wastewater treatment

The authors reported a potential candidate methylated mud snail protein (MeMsp) as an effective and eco-friendly flocculant to treat the high turbidity wastewater. MeMsp was obtained by extraction of mud snail protein (Msp) through isoelectric precipitation (PSC-IP) and then methylated via the esterification with side-chain carboxyl. Structural characterization of FT-IR, zeta potential and elemental analysis were carried out and further confirmed the successful of the methylation. Flocculation experiments with kaolin suspension simulated wastewater indicated that MeMsp-24 displayed more excellent flocculation efficiency at a low dosage. At the optimum dosage 27 mg/L, the maximum clarification efficiency of MeMsp-24 was 97.46% under pH 7.0. Furthermore, MeMsp-24 exhibited a wide flocculation window in the pH range 1.0–9.0, and faster sedimentation velocity and larger flocs size. In addition, MeMsp-24 exhibited 92.12% clarification efficiency in treating railway tunnel construction effluent. The flocculation kinetic and mechanism analysis revealed that the most effective particle collision occurred at the optimal dosage, with charge neutralization and adhesion playing irreplaceable roles in different environments, respectively. Therefore, through extraction and methylation modification, MeMsp could be a promising eco-friendly flocculant for high turbidity wastewater treatment.