Efficient treatment of starch wastewater through metallic-starch complexes and magnetic flocculation

Starch wastewater poses significant environmental harm, necessitating the implementation of effective treatment methods. The current starch wastewater treatment methods have some drawbacks, such as limited application scenarios, complicated process and insufficient purification efficiency. This study focuses on the purification of starch wastewater through metallic-starch complexes (MSCs) and magnetic flocculation. Metal ions (Fe3+, Pb2+ and Al3+) were added to interact with starch and coagulate, forming MSCs, in which the O6 atom of the branched chain methanol most likely to interact with metal ions. Then, the magnetic particles, sintering dust (SD), was utilized to adsorb the MSCs and form magnetic flocs, facilitating their rapid settlement under an external magnetic field. The purification experiments were aimed at a high-concentration starch wastewater with COD concentration of 12,000 mg/L, and the results demonstrated the metal ions could effectively coordinate with starch and form MSCs, achieving a COD removal rate of over 90%. Meanwhile, to address the challenge of difficult settlement of MSCs, the addition of SD induced the magnetic flocculation with MSCs through Van der Waals force and electrostatic force, which effectively reduced settling time and decreased sedimentation layer thickness. The combined use of MSCs and magnetic flocculation achieved efficient purification of starch wastewater.