Preparation of a Novel Cationic Starch Bioflocculant and Its Application Performance in Municipal Sewage Odor Mitigation and Sludge Dewatering

The supernatant fluid and sludge produced by traditional polyacrylamide flocculant (PAM) flocculation of municipal sewage emit a strong odor, and the dewatering performance of flocculant flocculating sludge based on acrylamide as the main synthetic raw material remains undesirable. In this study, we investigated a new green bioflocculant called SDF. This bioflocculant was made using 3-chloro-2-hydroxypropyl-modified starch as the raw material, acrylamide as the monomer, cerium nitrate as the initiator, and dextrin and bone gum as fillers. The results of the study indicated that the SDF-flocculated sludge exhibited a larger pore structure, superior dewatering performance, and a lower intensity of malodorous substances in the supernatant compared to PAM. Furthermore, it was found that the component with the strongest odor in the supernatant detected through purge and trap-gas chromatography–mass spectrometry was ethanethiol, and it was observed that the signal intensity released from the SDF supernatant was 30.62% lower on the first day and 7.91% lower cumulatively over the course of 7 days when compared to PAM. As a consequence, the SDF materials offer promising potential for treating odorous gas and reducing sludge in sewage treatment plants due to their easy fabrication, low cost, and superior dewatering performance.